CN107393941A - Low-temperature microwave source, low-temperature microwave source chip and preparation method thereof - Google Patents

Low-temperature microwave source, low-temperature microwave source chip and preparation method thereof Download PDF

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Publication number
CN107393941A
CN107393941A CN201710685503.0A CN201710685503A CN107393941A CN 107393941 A CN107393941 A CN 107393941A CN 201710685503 A CN201710685503 A CN 201710685503A CN 107393941 A CN107393941 A CN 107393941A
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low
bias
line
microwave source
transmission chamber
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CN107393941B (en
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郭国平
段鹏
孔伟成
贾志龙
薛光明
郭光灿
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University of Science and Technology of China USTC
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University of Science and Technology of China USTC
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N69/00—Integrated devices, or assemblies of multiple devices, comprising at least one superconducting element covered by group H10N60/00
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/01—Manufacture or treatment
    • H10N60/0912—Manufacture or treatment of Josephson-effect devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/10—Junction-based devices
    • H10N60/12—Josephson-effect devices

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  • Manufacturing & Machinery (AREA)
  • Superconductor Devices And Manufacturing Methods Thereof (AREA)

Abstract

The invention discloses a kind of low-temperature microwave source, low-temperature microwave source chip and preparation method thereof, the chip includes substrate and transmission chamber, bias junctions, voltage bias line and direct current biasing line on substrate surface；Transmission chamber includes SQUID chains, for launching microwave photon；Bias junctions electrically connect with transmission chamber, for producing microwave photon；Voltage bias line is used to apply bias voltage for bias junctions, the electronics Cooper pair in bias junctions is converted into microwave photon by way of stimulated emission；Direct current biasing line is used to apply magnetic field for transmission chamber；The resonant frequency for wherein transmiting chamber is determined by the total capacitance and total inductance of SQUID chains；The total inductance of SQUID chains changes with the change of magnetic field size, and the size in magnetic field changes with the change of size of current in direct current biasing line.Low-temperature microwave source chip provided by the invention is that microwave photon is produced by way of stimulated emission, ensure that the frequency, amplitude, the stability of phase for the microwave photon launched, meets the requirement of microwave source.

Description

Low-temperature microwave source, low-temperature microwave source chip and preparation method thereof
Technical field
The present invention relates to microwave circuit element, more specifically, is related to a kind of low-temperature microwave source, low-temperature microwave source chip And preparation method thereof.
Background technology
In solid state quantum computing field, only quantum chip is placed in the environment of extremely low temperature, could fully highlighted Go out the Quantum Properties of quantum bit, and also need to suppress influence of the ambient noise to quantum coherence.But in the prior art The e measurement technology used when being manipulated to quantum bit, quantum bit is such as entirely manipulated come what is carried out using classical instrument When used microwave source, it is difficult to meet the needs of manipulation of current solid state quantum chip and quantum calculation.
, the problem of noise is big, the opposing party on the one hand be present in used microwave source when manipulating quantum bit in the prior art Face, by then passing through the microwave source of room temperature circuit application, before microwave signal is from room temperature to extremely low temperature quantum chip, it is also necessary to enter The optimization designs such as the numerous and diverse filtering of row, decay, but can not still reach solid state quantum chip often over the microwave signal after optimization Manipulation and the demand of quantum calculation.
The content of the invention
In view of this, the invention provides a kind of low-temperature microwave source, low-temperature microwave source chip and preparation method thereof, the low temperature The manufacture craft of microwave source chip and the process compatible of quantum chip, directly can be integrated into quantum core by the low-temperature microwave source chip On piece, so as to directly carry out manipulation in situ to quantum bit, solves the problems, such as microwave source in the prior art.
To achieve the above object, technical scheme provided by the invention is as follows：
A kind of low-temperature microwave source chip, including substrate and transmission chamber, bias junctions, voltage bias on substrate surface Line and direct current biasing line；
Wherein, the transmission chamber is used to launch microwave photon, and the transmission chamber includes SQUID chains, and the SQUID chains include Multiple SQUID structures, the multiple SQUID structures are serially connected；
The bias junctions electrically connect with the transmission chamber, for producing microwave photon；
The voltage bias line is used to apply bias voltage for the bias junctions, makes the electronics Cooper pair in the bias junctions By way of stimulated emission, microwave photon is converted into；
The direct current biasing line is used to apply magnetic field for the transmission chamber；
Wherein, the resonant frequency of the transmission chamber is determined by the total capacitance and total inductance of the SQUID chains；The SQUID The total inductance of chain changes with the change of the magnetic field size, and the size in the magnetic field is with size of current in the direct current biasing line Change and change.
Preferably, the total inductance of the transmission chamber is more than the total inductance of the bias junctions, so that the electronics Cooper pair exists In the case that constant pressure biases, by being generated or absorbed by a photon, you can be tunneled through the bias junctions.
Preferably, the emission rate when microwave photon is launched from the transmission chamber, less than the electronic library Amber is to being tunneled through the tunneling rates of the bias junctions, so that the microwave photon is before launching, again by the electricity Sub- Cooper pair absorbs, to promote the tunnelling next time of the electronics Cooper pair, with lasting generation microwave photon.
Preferably, the SQUID structures are the cyclic structure that two Josephson junctions in parallel are formed；
The Josephson junction includes the first superconducting layer, insulating barrier and the second superconduction for being sequentially located at the substrate surface Layer.
Preferably, the direct current biasing line includes the electrode strip of strip, the long side of the electrode strip and the SQUID chains It is arranged in parallel.
Preferably, the substrate surface is in addition to the transmission chamber, bias junctions, voltage bias line and direct current biasing line, Also include metal level, the metal level surrounds transmission chamber, bias junctions, voltage bias line and the direct current biasing line, and described Metal level, the voltage bias line and the direct current biasing line are formed in same photoetching process；
The transmission chamber positioned at the metal level of its both sides and the direct current biasing line with forming co-planar waveguide knot respectively Structure；
The direct current biasing line and the metal level around it form coplanar waveguide structure.
Preferably, Josephson junction is become in the biasing.
Preferably, one end of the bias junctions and the output end of the transmission chamber are joined directly together, the other end and the metal Layer is joined directly together.
Preferably, the formation direction of the bias junctions is consistent with the formation direction of Josephson junction in SQUID chains transmission chamber, So that the bias junctions are formed with the SQUID chains in same processing step.
Preferably, the connected mode of the bias junctions and the output end of the transmission chamber is：It is described transmission chamber long side and Close to the position of the transmission chamber output end, extend the conductive material of strip as the first connecting line, first connection Line directly contacts with the first side of the bias junctions；
The bias junctions and the connected mode of the metal level are：Extend strip on the second side of the bias junctions Conductive material as the second connecting line, make by the conductive material that strip is extended upward towards the side of the bias junctions in metal level For the 3rd connecting line, second connecting line is joined directly together with the 3rd connecting line, and the angle of the two is right angle, described inclined It is along relative two sides in the transmission cavity length direction while with second to put the first of knot.
Preferably, first connecting line, second connecting line are formed with the bias junctions in same processing step； 3rd connecting line is formed with the metal level in same processing step.
Preferably, the connected mode of the bias junctions and the output end of the transmission chamber is：It is described transmission chamber long side and Close to the position of the transmission chamber output end, extend the conductive material of strip as the first connecting line, first connection Line directly contacts with the first side of the bias junctions；
The bias junctions and the connected mode of the metal level are：Extend strip on the second side of the bias junctions Conductive material as the 4th connecting line, make by the conductive material that strip is extended upward towards the side of the bias junctions in metal level For the 3rd connecting line, in the conductive material that the side of afterbody towards the 4th connecting line of the 3rd connecting line extends upward As the 5th connecting line, the 4th connecting line overlaps with the 5th connecting line, and the 3rd connecting line and the described 5th The angle of connecting line is right angle, and the first of the bias junctions be along relative two in the transmission cavity length direction while with second Side.
Preferably, first connecting line, the 4th connecting line are formed with the bias junctions in same processing step, 3rd connecting line, the 5th connecting line are formed with the metal level in same processing step.
Preferably, the voltage bias line includes battery lead plate, and the inductance around the battery lead plate, and the of the inductance One end is directly connected with the battery lead plate, and the second end is connected with the transmission chamber.
Preferably, the transmission chamber be half-wavelength resonator, and the center for transmiting chamber is voltage node, the electricity Center of second end of sense directly with the transmission chamber is connected.
Preferably, the output end of the transmission chamber and the first coupled capacitor C1 of the metal interlevel and the transmission chamber Relation between input and the second coupled capacitor C2 of the metal interlevel is C1：C2≥10:1, the microwave photon is from institute The speed Ω for stating the output end transmitting of transmission chamber is proportional to C12。
Preferably, the resonant frequency f of the transmission chamber meets relational expression with the constant pressure U applied in the voltage bias line Mhf=2eU, wherein, m is positive integer, and h is Planck's constant, and e is the electricity of an electronics；Wherein, the resonance of the transmission chamber Frequency is equal to the output frequency in the low-temperature microwave source.
Preferably, the total inductance L=L of the transmission chamber0+nLj/ 2, the total capacitance C=nc+cj of the transmission chamber, resonance frequency RateWherein, LjFor the inductance of single Josephson junction, L0For the electricity between the SQUID chains and the metal level Sense, electric capacity of the c between single SQUID structures and the metal level, cj are the SQUID chains electric capacity of itself, and n is the SQUID The quantity of SQUID structures on chain.
Preferably, transmission chamber, the bias junctions, the voltage bias line, the direct current biasing line and the metal The material of layer is low temperature superconducting material.
Preferably, the material of the metal level, the voltage bias line and the direct current biasing line be aluminium or niobium or Niobium nitride or titanium niobium nitride.
Preferably, the transmission chamber and the material of the bias junctions are aluminium.
Preferably, in addition to positioned at the substrate away from the laminated metal heat sink of the metal, with micro- to the low temperature Wave source chip is radiated.
The invention also discloses a kind of low-temperature microwave source, including described in control circuit and claim any one of 1-19 Low-temperature microwave source chip, the control circuit are used to apply operating voltage for the low-temperature microwave source chip, produce it concurrent Penetrate microwave photon；
Wherein, the control circuit includes constant-current source, and the mu balanced circuit being connected with the voltage bias line；
The constant-current source is used to provide power input for the mu balanced circuit；
The mu balanced circuit is used to provide bias voltage for the bias junctions in the low-temperature microwave source；
Wherein, the constant-current source is arranged under room temperature environment, and the low-temperature microwave source chip is arranged under low temperature environment, institute Stating mu balanced circuit includes room temperature mu balanced circuit and low temperature mu balanced circuit, the low temperature mu balanced circuit and the low-temperature microwave source chip It is arranged under identical environment.
Preferably, the room temperature mu balanced circuit includes the first low pass filter electrically connected with the constant-current source, for disappearing Except the voltage pulsation caused by the noise on circuit；
The low temperature mu balanced circuit includes：
The second low pass filter electrically connected with first low pass filter, for eliminating because the noise on circuit causes Voltage pulsation；
First divider resistance, the second divider resistance and the first impedance ground element, first divider resistance and second point Piezoresistance is connected with the voltage bias line, and the first end of first divider resistance electrically connects the first of the second divider resistance End, the second end are grounded by the first impedance ground element, the second end and the voltage bias of second divider resistance The battery lead plate of line electrically connects, in the course of work, the metal level ground connection；
The output end of the constant-current source is by the first low pass filter and the second low pass filter, with first partial pressure electricity The first end of resistance electrically connects, and in the course of work, passes through the inductance of the voltage bias line, the transmission chamber and the metal Layer, the bias voltage that the constant-current source provides is applied to the both ends of bias junctions.
Preferably, the room temperature mu balanced circuit also includes：
Differential voltage table, for detecting the voltage at the second divider resistance both ends；
3rd low pass filter and the 4th low pass filter, for eliminating the voltage pulsation caused by the noise on circuit；
The low temperature mu balanced circuit also includes：
5th low pass filter and the 6th low pass filter, for eliminating the voltage pulsation caused by the noise on circuit；
First electric capacity and the second impedance ground element, the second electric capacity and the 3rd impedance ground element, for isolation circuit Thermal noise；
Wherein, the first end of the differential voltage table passes through the 3rd low pass filter and the 5th LPF Device, it is connected with the first end of second divider resistance, the second end of the differential voltage table passes through the 4th LPF Device and the 6th low pass filter, are connected with the second end of second divider resistance；First pole plate of first electric capacity It is connected with the first end of second divider resistance, the second pole plate is grounded by the second impedance ground element；Described second First pole plate of electric capacity is connected with the second end of second divider resistance, and the second pole plate passes through the 3rd impedance ground element Ground connection；
Voltage U=IR1- [(R1/R2)+1] U ' being applied in the voltage bias line, wherein, R1 is described first point The resistance of piezoresistance, R2 are the resistance of second divider resistance, and I is the current value of the constant-current source, and U ' is described second point The voltage at piezoresistance both ends.
Preferably, the quantity of the bandpass filter of the first low pass filter-the six is at least one, the low temperature voltage stabilizing The wire for being used to connect each circuit element in circuit is low temperature direct wire, the low-temperature microwave source chip and the low temperature Mu balanced circuit is arranged on same circuit board.
Preferably, the control circuit also includes the current regulating circuit and DC source being connected with the direct current biasing line；
The DC source is used for the direct current biasing line output current；
The current regulating circuit is used to export the DC source to the size of current of the direct current biasing line to adjust Section.
Preferably, within 1GHz-10GHz, the regulations speed of output frequency exists the output frequency in the low-temperature microwave source Hundred nanosecond rank, power output is in -90dBm within -140dBm, and energy conversion efficiency is more than 10%.
The invention also discloses a kind of low-temperature microwave source chip preparation method, for making above-described low-temperature microwave source Chip, including：
Substrate is provided；
Metal level is formed over the substrate；
In same processing step, remove transmission cavity region and bias whole metal levels of tie region, and it is inclined to remove voltage The partial metal layers in line region and direct current biasing line region are put, to form the voltage bias line and the direct current biasing line, and Input and output end are formed at the both ends of the transmission cavity region, the output end is located at one close to the biasing tie region Side；
In same processing step, the transmission chamber for including SQUID chains is formed in the substrate surface of the transmission cavity region, and Bias junctions are formed in the substrate surface of the biasing tie region.
Preferably, the voltage bias line includes battery lead plate, and the inductance around the battery lead plate, the direct current biasing Line includes the electrode strip of strip, the whole metal levels for removing transmission cavity region and biasing tie region, and it is inclined to remove voltage The partial metal layers in line region and direct current biasing line region are put, to form the voltage bias line and the direct current biasing line, bag Include：
Form photoresist layer in the layer on surface of metal, the photoresist layer cover the battery lead plate, the inductance and The electrode strip region of the strip, and the transmission cavity region and biasing tie region are exposed, and the inductance and described The metal level of electrode strip periphery certain area；
Using the photoresist layer as mask, the metal layer material not covered by the photoresist layer is etched away；
The photoresist layer is removed, retains the electrode strip of the battery lead plate, the inductance and the strip.
Preferably, the transmission chamber of SQUID chains is included in the substrate surface formation for transmiting cavity region, and in the biasing The substrate surface of tie region forms bias junctions, including：
In the substrate surface of the transmission cavity region and the substrate surface of the biasing tie region, the first light is sequentially formed Photoresist layer and the second photoresist layer；
Development is exposed to first photoresist layer and the second photoresist layer, to be formed along the transmission cavity region Multiple hanging bridge structures that length direction is arranged in order, the hanging bridge structure be removed by the first photoresist layer of bottom second Photoresist layer is formed；
Using the hanging bridge structure as mask, the first superconducting layer is formed in the substrate surface using the first incident angle；
The surface of first superconducting layer is aoxidized, to form insulating barrier；
Using the hanging bridge structure as mask, the second superconducting layer is formed in the surface of insulating layer using the second incident angle；
Wherein, in first superconducting layer, the insulating barrier and second superconduction of the hanging bridge structure lower zone The lamination that layer is formed forms the Josephson junction, becomes the bias junctions in the Josephson that the biasing tie region is formed； On the transmission cavity length direction, the superconduction layer material between adjacent two hanging bridge structures forms conducting interval structure, On the transmission chamber width, two Josephson junctions positioned at the hanging bridge structure both sides pass through the conducting interval respectively Structure is in parallel to form the SQUID structures, and on the transmission cavity length direction, multiple SQUID structures pass through between the conduction The SQUID chains are formed every structures in series.
Compared to prior art, technical scheme provided by the invention at least has advantages below：
The invention provides a kind of low-temperature microwave source, low-temperature microwave source chip and preparation method thereof, low-temperature microwave source bag Low-temperature microwave source chip and control circuit are included, control circuit is used to apply operating voltage for low-temperature microwave source chip, makes its generation And launch microwave photon, wherein, transmission chamber, bias junctions, voltage bias line and direct current biasing on the low-temperature microwave source chip Line etc., made by semiconductor technology, its manufacture craft is compatible with the manufacture craft of quantum chip, therefore can be by the low temperature Microwave source chip is together with quantum integrated chip, i.e., in the course of work, the low-temperature microwave source chip and quantum chip common point Under low temperature environment, so as to which at low ambient temperatures, the microwave photon launched by the low-temperature microwave source chip can be directly to amount Sub- bit carries out manipulation in situ, avoids a variety of drawbacks for applying microwave source by room temperature circuit in the prior art.
Also, low-temperature microwave source chip provided by the invention is that microwave photon is produced by way of stimulated emission, ensure Frequency, amplitude, the stability of phase for the microwave photon launched, meet the requirement of microwave source.Meanwhile the low temperature is micro- The output frequency of wave source is the resonant frequency for transmiting chamber, and the resonant frequency for transmiting chamber can be by regulation direct-current bias line The size of electric current and adjust, so as to meet quantum chip manipulation needed for reference frequency output.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing There is the required accompanying drawing used in technology description to be briefly described, it should be apparent that, drawings in the following description are only this The embodiment of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can also basis The accompanying drawing of offer obtains other accompanying drawings.
Fig. 1 is a kind of top view for low-temperature microwave source chip that the embodiment of the present application provides；
Fig. 2 is the top perspective view of SQUID chain structures in a kind of low-temperature microwave source chip that the embodiment of the present application provides；
Fig. 3 is the profile of Josephson junction；
Fig. 4 is schematic diagram of the voltage bias line with transmiting chamber connected mode；
Fig. 5 a- Fig. 5 b are respectively the top perspective view for two kinds of bias junctions connected modes that the embodiment of the present application provides；
Fig. 6-Fig. 7 is a kind of top view for each step of low-temperature microwave source chip preparation method that the embodiment of the present application provides；
Fig. 8 is the top view after transmission cavity region and the photoetching of bias junctions region；
Fig. 9 is the profile that the hanging bridge structure D of transmission cavity region is cut along AA '；
Figure 10 is the profile that the hanging bridge structure D of transmission cavity region is cut along BB '；
Figure 11-Figure 13 is the profile of each step of Josephson junction preparation method；
Figure 14 is the top perspective view after the photoetching of bias junctions region；
Figure 15 is the profile that the hanging bridge structure D of biasing tie region is cut along AA '；
Figure 16 is the profile that the hanging bridge structure D of biasing tie region is cut along BB '；
Figure 17 is a kind of circuit structure diagram in low-temperature microwave source that the embodiment of the present application provides.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete Site preparation describes, it is clear that described embodiment is only part of the embodiment of the present invention, rather than whole embodiments.It is based on Embodiment in the present invention, those of ordinary skill in the art are obtained every other under the premise of creative work is not made Embodiment, belong to the scope of protection of the invention.
The embodiments of the invention provide a kind of low-temperature microwave source chip, specifically, as shown in figure 1, being the low-temperature microwave source The top view of chip, the low-temperature microwave source chip include substrate 1 and transmission chamber 2, bias junctions 4, electricity on the surface of substrate 1 Press offset line 5 and direct current biasing line 3.
Wherein, substrate 1 is semiconductor chip, for example, silicon or sapphire etc..Due to monocrystalline silicon and the medium of sapphire material Be lost it is minimum, thereby it can be assured that the service behaviour of low-temperature microwave source chip reaches optimum state.Alternatively, substrate 1 can be The sapphire substrate that crystal orientation is 100, thickness is 0.5mm.Further, the scattering tangent value of the sapphire substrate can be 2e-7。 In the present embodiment, the low-temperature microwave source chip is prepared on the semiconductor substrate by semiconductor nano process technology, its overall chi It is very little to be less than 1mm × 1mm.
Specifically, the transmission chamber 2 is used to launch microwave photon, transmission chamber 2 includes SQUID chains, and the SQUID chains include Multiple SQUID structures, the multiple SQUID structures are serially connected；
The bias junctions 4 electrically connect with the transmission chamber 2, for producing microwave photon；
The voltage bias line 5 is used to apply bias voltage for the bias junctions 4, makes the electronic library in the bias junctions 4 Amber is to by way of stimulated emission, being converted into microwave photon；
The direct current biasing line 3 is used to apply magnetic field for the transmission chamber 2；
Wherein, the resonant frequency of the transmission chamber 2 is determined by the total capacitance and total inductance of the SQUID chains；The SQUID The total inductance of chain changes with the change of the magnetic field size, and the size in the magnetic field is with size of current in the direct current biasing line Change and change.
It should be noted that the surface of substrate 1 is inclined except the transmission chamber 2, bias junctions 4, voltage bias line 5 and direct current Put outside line 3, in addition to metal level 6, as shown in figure 1, the metal level 6 surrounds the transmission chamber 2, bias junctions 4, voltage bias Line 5 and direct current biasing line 3, and the metal level 6, the voltage bias line 5 and the direct current biasing line 3 are in same photoetching During formed.
Metal level 6 in the present embodiment is grounded.As long as it will be understood by those skilled in the art that low-temperature microwave source chip and amount Sub- chip is in integrated state, and when quantum chip is placed in low temperature environment, low-temperature microwave source chip is also placed in low temperature simultaneously Environment, regardless of whether the low-temperature microwave source comprising the low-temperature microwave source chip is in running order, the metal level 6 is in connecing The state on ground.
The embodiment of the present invention is that microwave photon is produced by the way of stimulated emission, this just need to transmit chamber and bias junctions with And the condition for being designed to meet stimulated emission by bias voltage that bias junctions apply.
It should be noted that the main body that stimulated emission produces microwave photon is the electronics Cooper pair in bias junctions, so-called electricity Sub- Cooper pair refers to two electronics near Fermi surface, because net sucking action be present, and forms bound state, this constraint State is that storehouse uncle is right, and the two corresponding electronics are electronics Cooper pair, or referred to as Cooper electronic pair.So-called Fermi surface is Refer to the constant energy surface in electronic state momentum space in metal.
To allow electronics Cooper pair stimulated emission to produce photon, then needing to provide enough energy for electronics Cooper pair makes it Shake off its bound state on Fermi surface, that is, allow electronics that energy level transition, in other words, i.e., the electronics Cooper pair in bias junctions occurs It is tunneled through bias junctions.And the premise that electronics Cooper pair is tunneled through bias junctions is, under superconducting state, bias junctions On the premise of both ends apply constant voltage U, and if only if absorbs or release is equal to 2eU energy ability for electronics Cooper pair Realization is tunneled through bias junctions.
Bias junctions in the present embodiment link together with transmission chamber, therefore this portion of energy needed for electron tunneling, then A photon can be generated or absorbed by by electronics to provide.But the premise that electronics can produce or absorb a photon is, Relational expression mhf=2eU need to be met by transmiting the resonant frequency f and constant pressure U applied in the voltage bias line of chamber, wherein, m is just Integer, h are Planck's constant, and h ≈ 6.626 × 10^-34Js, e are the electricity of an electronics.By the way of stimulated emission Caused microwave photon finally exports from transmission chamber, and the microwave photon being generated and transmitted by out using stimulated emission mode, its Frequency, amplitude and phase can reach the stabilization of height, meet the requirement of microwave source.
In order to ensure the tunnelling process Infinite Cyclic of the tunnelling of electronics Cooper pair, and electronics Cooper pair is gone down, it is necessary to full The following two conditions of foot, condition 1 is coupling condition, and condition 2 is stimulated emission condition：
1) equation below is met when microwave source works：
Wherein,Represent electric current total phase of the microwave photon in chamber is transmitted, κcRepresent total dissipation of transmission chamber, IjFor Bias junctions critical current,For quantum magnetic flux,For by the magnetic flux inside SQUID chains, wherein, ω0=2 π f, f are Penetrate the resonant frequency of chamber, κc=Ω+κi, Ω be transmission chamber output port photon emission rate, κiFor the energy in transmission intracavitary portion Dissipative shock wave,L is the total inductance of transmission chamber, and Lj is the total inductance of bias junctions.
In order that microwave source can effectively work, it is necessary to protect on the basis of bias junctions both ends application constant bias voltage The efficiency that the energy discharged during electronic library uncle is demonstrate,proved to being tunneled through bias junctions is converted into microwave photon is sufficiently high, i.e., partially Putting knot and transmission chamber needs good enough coupling, corresponds in above equation, it is necessary to make photon generating item (the i.e. in equation Four) with equation in Section 3 ratio be more than 1, i.e.,L/L is obtained by equivalence transformationj ＞ 1.
That is, in order to realize tunnelling, the total inductance L of the transmission chamber 2 in the present embodiment need to be more than the biasing The total inductance Lj of knot 4 so that the electronics Cooper pair constant pressure bias in the case of, by being generated or absorbed by a photon, i.e., The bias junctions can be tunneled through, if conversely, the total inductance L of transmission chamber 2 is less than the total inductance Lj of bias junctions 4, electronics cooper Process to that can not complete to be generated or absorbed by a photon.
In order to meet this condition, the bias junctions 4 in the present embodiment are Josephson junction, also, are formed using SQUID chains Chamber 2 is transmitted, the Josephson junction includes the first superconducting layer, insulating barrier and the second superconduction for being sequentially located at the substrate surface Layer, specific forming method are described in detail again in the examples below.
As shown in Figure 1-2, Fig. 2 is the enlarged drawing of SQUID chain structures to the structure of transmission chamber 2, and SQUID chains include multiple SQUID structures 20, and multiple SQUID structures 20 are serially connected, and are conducting interval structure 23 between multiple SQUID structures 20. Specifically, SQUID structures 20 are the cyclic structure that two Josephson junctions 21 in parallel are formed, between two Josephson junctions 21 For white space 22, backing material is directly exposed on white space 22, two Josephson junctions 21 are by positioned at its both sides Conducting interval structure 23 realizes parallel connection, that is to say, that two Josephson junctions 21 are by being arranged between adjacent SQUID structures Conducting interval structure 23 realize parallel connection.Also, multiple SQUID structures are also by being arranged between adjacent SQUID structures Conducting interval structure 23 realize series connection.
As shown in figure 3, it is the profile of Josephson junction 21, the structure of Josephson junction 21 is superconducting metal layer/(insulation Layer or semiconductor layer)/superconducting metal layer form sandwich structure, material used in each layer, can all directly affect about plucked instrument The physical property of the gloomy knot of husband.In order to meet the performance requirement of low-temperature microwave source chip, preferably Josephson junction 21 in the present embodiment Structure include being sequentially located at the first superconducting layer 211, the superconducting layer 213 of insulating barrier 212 and second on the surface of substrate 1.Also, first The superconducting layer 213 of superconducting layer 211 and second is made using low temperature superconducting material, and insulating barrier 212 is to the first superconducting layer 211 surface aoxidize the insulating barrier of formation.Further, due to technique that other superconducting metal materials prepare Josephson junction It is complex, in order to simplify the manufacture craft of transmission chamber in the present embodiment, and in order to by the manufacture craft of transmission chamber and subsequently The manufacture craft of quantum chip is compatible, in order to by integrated, preferably first superconduction of the low-temperature microwave source chip and quantum chip The material of the superconducting layer 213 of layer 211 and second is aluminium, and the material of insulating barrier 212 is aluminum oxide.
Two Josephson junctions 21 in SQUID structures 20 in the present embodiment, with bias junctions 4 in same processing step Formed, also, conducting interval structure 23 and formed in the forming process of Josephson junction 21, but according to different zones, Different sizes, the cross-section structure of conducting interval structure 23 are also not quite similar, and this is described in detail in following methods embodiment.
Two Josephson junctions 21 in SQUID structures 20 in the present embodiment, with bias junctions 4 in same processing step Formed.Even the inductance of bias junctions 4 is the inductance L of a Josephson junction0, then the total inductance L for transmiting chamber is institute on SQUID chains There is the inductance sum of Josephson junction, along with the inductance L between SQUID chains and ground0, i.e. L=nLj/2+L0, n SQUID The quantity of Josephson junction on chain.The quantity of the Josephson junction in transmission chamber in the present embodiment has up to a hundred, therefore thoroughly The total inductance for penetrating chamber is about tens times of bias junctions total inductance, or even hundreds of times, meets the coupling bar of above microwave photon transmitting Part.
2) in order that the stimulated emission process Infinite Cyclic of electronics Cooper pair is gone down, constantly launch under constant pressure biasing micro- Glistening light of waves, it is also necessary to control microwave photon from the size for transmiting emission rate Ω when launching in chamber, i.e. ensure micro- Emission rate Ω when glistening light of waves is launched from the transmission chamber, the bias junctions 4 are tunneled through less than electronics Cooper pair Tunneling rates Γ, that is, meet Γ ＞ Ω, so that the microwave photon is before launching, again by the electronics Cooper pair Absorb, to promote the tunnelling next time of the electronics Cooper pair, promote electronics Cooper pair to continue tunnelling to be formed, persistently produce micro- Glistening light of waves.
Specifically, when Γ=I/2e, wherein I are bias junctions both ends application bias voltage U, pass through the reality at bias junctions both ends DC current, the m in formula mhf=2eU is bigger, then I is bigger, then electronics Cooper pair is tunneled through the tunnelling of the bias junctions 4 Speed Γ is bigger.
Emission rate when microwave photon is launched from the transmission chamber, by the input 24 and output end of transmission chamber The size of coupled capacitor between 25 and metal level 6 determines, specifically, the output end of transmission chamber and the coupling electricity of the metal interlevel Hold for the first coupled capacitor C1, the coupled capacitor of the input and the metal interlevel of the transmission chamber is the second coupled capacitor C2, the speed that microwave photon is launched from the transmission chamber are proportional to (C12+C22), wherein, output of the microwave photon from transmission chamber The speed Ω (i.e. effective speed) of end transmitting is proportional to C12。
By reducing C1 and C2 size as far as possible in the present embodiment, launch so as to reduce microwave photon from the transmission chamber Emission rate Ω when going out, and by the bias voltage U at increase bias junctions both ends as far as possible, so as to increase electronics Cooper pair tunnel The tunneling rates Γ of the excessively described bias junctions 4 of break-through, so as to meet Γ ＞ Ω.
Specifically, can be by adjusting transmission chamber input and the shape of output end and the port electrode of metal interlevel, adjustment C1 and C2 size, such as reduce the port of increase transmission chamber and the distance of metal interlevel, while reduce the facing area between the two, C1 and C2 can be reduced.
By the transmission chamber of above structure in the present embodiment, ensure that the electronics Cooper pair in bias junctions 4 continues quilt Excite, so as to persistently launch microwave photon, realize the function of microwave source.
Specifically, as shown in figure 1, one end of bias junctions 4 described in the embodiment of the present invention and the output end of the transmission chamber 2 It is joined directly together, the other end is joined directly together with the metal level 6, i.e., in the course of the work, bias junctions 4 are directly connect by metal level 6 Ground, so as to the stiffness of coupling for enhancing bias junctions 4 to the full extent with transmiting chamber 2, the loss of signal is avoided, to improve low temperature The energy conversion efficiency of microwave source.
Bias junctions 4 described in the present embodiment form direction and the formation direction of Josephson junction in SQUID chains transmission chamber Unanimously, so that the bias junctions are formed with the SQUID chains in same processing step.Bias the connection mode of tie region at least Have following two, illustrate respectively below in conjunction with the accompanying drawings.
As shown in Figure 5 a, the metal on the periphery of bias junctions 4 is arranged to hollow shape, respectively with metal level 6 and transmission chamber it is defeated Go out end 25 to be connected.Specifically, the connected mode of bias junctions 4 and the output end 25 of the transmission chamber 2 is：Grown in the transmission chamber 2 Side and the position of the close transmission output end 25 of chamber 2, extend the conductive material of strip as the first connecting line 43, described First connecting line 43 directly contacts with the first side 41 of the bias junctions 4.The bias junctions 4 and the connection side of the metal level 8 Formula is：Extend the conductive material of strip on the second side 42 of the bias junctions 4 as the second connecting line 44, in metal level 6 The conductive material of strip is extended upward as the 3rd connecting line 45, second connecting line 44 towards the side of the bias junctions Be joined directly together with the 3rd connecting line 45, and the angle of the two is right angle, the bias junctions first at 41 and second 42 To transmit two relative sides of cavity length direction along described.In order to accelerate process speed, the first connecting line 43, in the present embodiment Two connecting lines 44 are formed with bias junctions 4 in same processing step, and the 3rd connecting line 45 is with metal level 6 in same processing step Formed.
In other embodiments, due to the difference of photoetching process selection, the time that technique is spent is also different, according to electricity The mode of beamlet direct write exposure, to form the connecting line on bias junctions periphery, the problem of needing to consider process efficiency, therefore, it is then Improve the photoetching process efficiency for forming bias junctions periphery connecting line, bias junctions 4 and the connected mode of transmission chamber 2 and metal level 6 As shown in Figure 5 b, specifically, the connected mode of bias junctions 4 and the output end 25 of the transmission chamber 2 is：Transmission the long side of chamber 2 and Close to the position of the transmission output end of chamber 2, the conductive material for extending strip connects as the first connecting line 43, described first Wiring 43 directly contacts with the first side of the bias junctions 4.
The bias junctions 4 and the connected mode of the metal level 6 are：Extend strip on the second side of the bias junctions 4 The conductive material of shape extends upward the conduction of strip in metal level as the 4th connecting line 46 towards the side of the bias junctions Material upwardly extends as the 3rd connecting line 45 in the side of afterbody towards the 4th connecting line 46 of the 3rd connecting line 45 The conductive material gone out overlaps as the 5th connecting line 47, the 4th connecting line 46 with the 5th connecting line 47, and described The angle of three connecting lines 45 and the 5th connecting line 47 is right angle, the bias junctions first at 41 and second 42 for along institute State two relative sides of transmission cavity length direction.
Wherein, first connecting line 43, the 4th connecting line 46 and the bias junctions 4 shape in same processing step Into the 3rd connecting line 45, the 5th connecting line 47 are formed with the metal level 6 in same processing step.
It should be noted that whether the bias voltage for being applied to bias junctions both ends is stablized, low-temperature microwave source is directly determined Output frequency whether stablize, based on this, referring to Fig. 1, the voltage bias line 5 in the present embodiment includes battery lead plate 51, Yi Jihuan Around the inductance 52 of the battery lead plate 51, in the course of work in low-temperature microwave source, battery lead plate 51 with outside low-temperature microwave source chip Circuit be connected, for receive external circuit be low-temperature microwave source chip provide constant bias voltage.The inductance 52 First end is directly connected with the battery lead plate 51, and the second end is connected with the transmission chamber 2, will by battery lead plate 51 and inductance 52 The bias voltage for coming from external circuit is applied in bias junctions.
In the course of work of low-temperature microwave source, inductance 52 can play a part of wave filter, on the one hand can prevent from transmiting chamber In energy leakage, on the one hand can also prevent the external world high-frequency noise enter transmission chamber caused by low-temperature microwave source performance Harmful effect, so as to improve the stability of bias voltage to a certain extent.In addition, low-temperature microwave source also add outside other Portion's circuit, for ensuring the stability of bias voltage, for the concrete structure of external circuit, following examples can be detailed to this progress Describe in detail bright, repeat no more here.
, can be effective in order to ensure the bias voltage of voltage bias line except the setting of this body structure of above voltage bias line Be applied in bias junctions, while to the full extent reduce bias voltage to transmission chamber in microwave signal influence, the present embodiment In preferably bias voltage is applied to transmission chamber voltage node position, and preferably, the transmission chamber 2 in the present embodiment is Half-wavelength resonator, the center of the transmission chamber 2 is voltage node, most weak in the electric-field intensity of position transmission chamber, because This, the second end of the inductance 52 in the present embodiment in voltage bias line 5 is directly connected with the center for transmiting chamber 2, i.e., Bias voltage is applied to the center of transmission chamber, so as to weaken shadow of the bias voltage to transmission chamber microwave signal to the full extent Ring, as shown in Figure 4.
It will be understood by those skilled in the art that according to quarter-wave reflection cavity, bias voltage can be caused not have One effective application position, so as to which the stimulated emission of electronics Cooper pair can not be realized.But due to using half-wavelength resonator then With two ports, i.e. input and output end, in order to ensure microwave photon is defeated by the output end for transmiting chamber in the present embodiment Go out, and the input for reducing microwave photon from transmission chamber as far as possible leaks and the caused loss of signal, preferred C1 in the present embodiment Magnitude relationship with C2 is C1：C2≈10:1, it is furthermore preferred that C1：C2≥10:1.
It should be noted that in the present embodiment, the output frequency in low-temperature microwave source is the output signal in low-temperature microwave source Frequency, the output frequency in low-temperature microwave source determines by the resonant frequency f of transmission chamber, and the low-temperature microwave source in the present embodiment Output frequency is equal to the resonant frequency f of transmission chamber.And the resonant frequency f of chamber is transmitted by the total capacitance and total inductance on SQUID chains Determine.
It should be noted that SQUID structures are a kind of superconducting quantum interference devices, as previously discussed, SQUID structures are by two The Josephson junction of individual superconduction cyclization in parallel, can change path in SQUID structures by the vertical magnetic field adjusted in SQUID structures The size of critical current, so as to change the size of SQUID structure inductance, that is, change the size of SQUID chain total inductances, and then change Transmit the resonant frequency f of chamber.
Concrete principle is to transmit the total inductance L=L0+nLj/2 of chamber 2, wherein, Lj is the inductance of single Josephson junction, Inductance of the L0 between SQUID chains and co-planar waveguide ground level, i.e. inductance of the L0 between SQUID chains and metal level 6, in fact, L0 1 to 2 orders of magnitude smaller than nLj/2, can ignore L0 in calculating process.Likewise, the total capacitance C=nc+ of transmission chamber 2 The electric capacity of cj, c between single SQUID structures and metal level 6, n be the SQUID chains on Josephson junction quantity, cj For the SQUID chains electric capacity of itself, but in fact, cj nearly 3 orders of magnitude smaller than nc, therefore, can ignore cj in calculating process. Based on case above, the resonant frequency of transmission chamber 2
According to tunnel-effect, the electronics Cooper pair in Josephson junction 21 can pass through intermediate insulating layer, the superconduction of appearance Electric current is without hindrance.When DC current by when, if electric current be less than Josephson junction 21 critical current, the Josephson junction 21 show without hindrance characteristic, this DC current for allowing non-zero by and keep the property that voltage is zero to turn into direct current Joseph Gloomy effect.Wherein, the critical current of Josephson junction 21 is very sensitive to the magnetic field of outside, that is to say, that is applied to Joseph Magnetic field on gloomy knot 21 can significantly influence the size of critical current.
Therefore, transmission chamber is formed using SQUID chains in the present embodiment, on the one hand meets above electronic library uncle to stimulated emission Condition, even if the total inductance of SQUID chains be much larger than bias junctions inductance, on the other hand, make the inductance of SQUID chains adjustable Scope is bigger, and regulative mode is simply direct, that is, passes through the size of the electric current in regulation direct-current bias line 3, you can regulation SQUID chains The size of the vertical magnetic field of upper application, so as to adjust the critical current of Josephson junction 21, and then adjust SQUID chain total inductances Size, and then the resonant frequency f of transmission chamber is adjusted, and then change the output frequency in low-temperature microwave source.In the present embodiment, Ke Yitong Cross the parameter for designing suitable SQUID chains 20 and specific magnetic field size, realize the output frequency in low-temperature microwave source 1GHz~ 10GHz frequency ranges are adjustable.
Specifically, as shown in figure 1, direct current biasing line 3 includes the electrode strip of strip in the present embodiment, the electrode strip Long side be arranged in parallel with the SQUID chains, so that transmission chamber 2 forms coplanar waveguide structure with direct current biasing line 3, also, Transmission chamber 2 part corresponding with the metal level 6 positioned at its side also forms coplanar waveguide structure, that is, transmits chamber 2 and serve as reasons The co-planar waveguide superconducting transmission line transmission chamber that SQUID chains are formed.Also, the direct current biasing line 3 and the metal around it Layer 6 forms coplanar waveguide structure, i.e. the structure of direct current biasing line is the co-planar waveguide that ground plane is directly arrived in end.
Can be that axle center forms Distribution of Magnetic Field with direct current biasing line 3 after DC current is passed through on direct current biasing line 3.Directly The electrode strip of stream offset line 3 be arranged in parallel with SQUID chains and can not only ensure that by the magnetic field of SQUID chains be vertical magnetic field, and And being uniformly distributed for magnetic field on whole SQUID chains 20 can be ensured.
Based on this, coplanar waveguide structure is formed between transmission chamber 2, direct current biasing line 3 and metal level 6, magnetic field can ensured While regulating effect so that direct current biasing line 3 possesses the ability in quick regulation magnetic field.Wherein, the speed in most fast regulation magnetic field Degree can reach nanoseconds up to a hundred, to meet ability that microwave source possesses high speed frequency conversion output, the low-temperature microwave in the present embodiment The output frequency in source can be adjusted in 1GHz~10GHz frequency ranges.
In addition, it is necessary to explanation, in order to meet primary condition that the stimulated emission quantum principles are realized, in the present embodiment Transmission chamber 2, bias junctions 4, voltage bias line 5, the material of direct current biasing line 3 and metal level 6 be low temperature superconducting material.It is more excellent Choosing, the material of metal level 6, voltage bias line 5 and direct current biasing line 3 is aluminium or niobium or niobium nitride or titanium niobium nitride. And in order to form Josephson junction, and enable the low-temperature microwave source chip compatible with subsequent technique, preferred transmission chamber 2 and biasing The material of knot 4 is aluminium.Based on this, the low-temperature microwave source chip can be operated in below corresponding superconduction critical temperature, not only may be used To meet the needs of low temperature weak signal process fields such as quantum bit manipulation, and current loss can be greatly reduced and add and make an uproar Sound.
Low-temperature microwave source chip in the present embodiment also includes the metal heat sink for deviating from the one side of metal level 6 positioned at substrate 1. In the course of work, the metal heat sink can not only radiate to low-temperature microwave source chip, be also used as low-temperature microwave source core The ground level of piece.That is, the battery lead plate 51 and metal level 6 of direct current biasing line 3, voltage bias line 5 with the bottom of substrate 1 Metal heat sink connection, to be grounded in the course of the work.
Low-temperature microwave source chip provided by the invention is that microwave photon is produced by way of stimulated emission, ensure that transmitting Frequency, amplitude, the stability of phase for the microwave photon gone out, meet the requirement of microwave source.Meanwhile the low-temperature microwave source Output frequency is the resonant frequency for transmiting chamber, and the resonant frequency for transmiting chamber can be by the electric current in regulation direct-current bias line Size and adjust, so as to meet quantum chip manipulation needed for reference frequency output.
Specifically, a kind of low-temperature microwave source chip that the present embodiment provides, the size of its whole chip is smaller, only 500 μ M × 600 μm, using the length for transmiting chamber as 400 μm, 48 SQUID structures of being connected on SQUID chains, the inductance of single SQUID structures Exemplified by 0.8nH, the upper limit output frequency of obtained low-temperature microwave source chip is 10.8GHz.In practical work process, pass through Apply different electric currents on direct current biasing line 3 to adjust the vertical magnetic field strength on SQUID chains, can be effectively micro- by low temperature The output frequency of wave source is continuously adjusted downward to 1GHz from 10GHz, to meet the requirement of low-temperature microwave source output frequency.
Specifically, in practical work process, the lower limit of the total inductance of SQUID chains, corresponding is microwave source output frequency The higher limit of rate.The thus low-temperature microwave source chip in the present embodiment, it is only necessary to be arranged to process by the total inductance value of SQUID chains The lower limit that technique can reach, redesign the length of suitable SQUID chains, you can make the maximum output frequency in low-temperature microwave source Reach 10GHz.
It should be noted that the length of chamber is transmitted in low-temperature microwave source chip in the present embodiment, SQUID on SQUID chains The quantity of structure, the inductance value of single SQUID structures include but is not limited to above numerical value, can be exported according to specific low-temperature microwave source The requirement of frequency, design different numerical value.
The embodiment of the present invention additionally provides a kind of low-temperature microwave source chip preparation method, is carried applied to any of the above-described embodiment The preparation of the low-temperature microwave source chip of confession, as shown in Fig. 6, Fig. 7, Fig. 1, specific preparation process includes the top view of its preparation process Following steps：
Step S1：As shown in Figure 6, there is provided substrate 1.
The substrate 1 is semiconductor chip, for example, silicon or sapphire substrate etc., so that substrate 1 is Sapphire Substrate as an example, such as Using the Sapphire Substrate of twin polishing, the crystal orientation of Sapphire Substrate can be [100] crystal orientation.It should be noted that the present embodiment In backing material and crystal orientation, thickness, the scattering selection such as tangent value, low-temperature microwave source can met according to impedance matching principle Suitable and cleaning backing material is selected on the basis of required output frequency, the present embodiment is not limited this.
Step S2：As shown in fig. 6, metal level 6 is formed on the substrate 1.
Specifically, electron beam evaporation process can be used or using techniques such as magnetron sputtering platings, gold is formed on the surface of substrate 1 Belong to layer 6, form the concrete technology of metal level 6 and the thickness requirement of metal level 6, can be according to the difference and thickness of metal layer material Difference is selected, and the present embodiment is not limited this.
The material of metal level 6 is superconductor, for example, if metal layer material selects aluminium, electron beam can be used to steam The techniques such as hair deposit certain thickness aluminium film on the surface of substrate 1, and because aluminium is as superconductor, its thickness requires more than 50nm ability Reach good superconducting state, therefore, the thickness of the aluminium film requires more than 50nm, as the aluminium film thickness for 60nm, 70nm, 80nm, 90nm or 100nm etc., specific thickness, the present embodiment are not limited this.
According to niobium as metal layer material, then the techniques such as magnetron sputtering can be used, certain thickness is deposited on the surface of substrate 1 Niobium film, because niobium as superconductor, its thickness requires more than 20nm and can be only achieved good superconducting state, therefore, the niobium film Thickness require more than 20nm, such as thickness of the niobium film is 30nm, 40nm, 60nm, 80nm or 100nm, specific thickness, this implementation Example is not limited this.
Step S3：As shown in fig. 7, in same processing step, remove transmission cavity region and bias all gold of tie region Belong to layer, and remove the partial metal layers in voltage bias line region and direct current biasing line region, to form the He of voltage bias line 5 The direct current biasing line 3, and the input 61 and output end 62 of transmission chamber are formed at the both ends of the transmission cavity region, it is described defeated Go out end 62 to be located at close to the side of the biasing tie region.
The figure that can be formed in the step using photoetching and etching technics in Fig. 7, for example, in the metal shown in Fig. 6 Spin coating photoresist on 6 surface of layer, afterwards using the mask plate with voltage bias line 5 and the grade structure graph of direct current biasing line 3, is adopted Development is exposed with ultraviolet photolithographic technology, covering transmission cavity region is removed and biases the photoresist of tie region, obtain that there is electricity Press the photoresist layer of offset line 5 and the grade structure graph of direct current biasing line 3；Afterwards, using reactive ion etching technology, with electricity The photoresist layer for pressing offset line 5 and the grade structure graph of direct current biasing line 3 is mask, removes the metal not covered by the photoresist layer Layer material, wash the photoresist layer again afterwards, so as to obtain the metal layer image shown in Fig. 7, that is, being formed includes battery lead plate 51 and the structure such as the direct current biasing line 3 of voltage bias line 5 including strip electrode strip of inductance 52 of surrounding electric poles plate 51.
It should be noted that the metal level that direct current biasing line region remains also constitutes lead 30 and lead 31, thoroughly The metal level for penetrating cavity region both ends is also etched and forms input 61 and output end 62.Wherein, it is worked in low-temperature microwave source Cheng Zhong, lead 30 and lead 31 electrically connect with the metal heat sink of the low-temperature microwave source chip bottom, also, with direct current biasing line 3 Metal heat sink of the connected external circuit also with the bottom of substrate 1 is connected, to realize the regulation to direct current biasing line current.Also, Metal heat sink of the battery lead plate 51 of voltage bias line 5 also with the low-temperature microwave source chip bottom electrically connects, meanwhile, it is battery lead plate 51 The external circuit for providing bias voltage also electrically connects with metal heat sink, so as to provide bias voltage for voltage bias line 5.
The metal level of transmission cavity region and biasing tie region in the etching process is removed, so as to the shape in following steps Into transmission chamber and bias junctions.
Step S4：As shown in figure 1, in same processing step, being formed in the substrate surface of the transmission cavity region includes The transmission chamber of SQUID chains, and form bias junctions in the substrate surface of the biasing tie region.
The basic structure of transmission chamber 2 including SQUID chains and bias junctions 4 in the present embodiment is Josephson junction, because It is identical with the processing step of bias junctions 4 that this forms transmission chamber 2.Specifically, with reference to the profile and top view of each step, it is right The technical process of transmission chamber 2 and bias junctions 4 illustrates.
As shown in figure 8, it is the top view after transmission cavity region and the photoetching of bias junctions region, specifically, in transmission cavity region Substrate surface and it is described biasing tie region substrate surface, the photoresist of two layers of different materials of spin coating, sequentially form first The photoresist layer 71 of photoresist layer 70 and second.In exposure process, needed for the first photoresist layer 70 and the second photoresist layer 71 Exposure dose difference is very big, so as to successfully be processed in exposure in hanging bridge structure D, Fig. 8 positioned at the dotted line frame of transmission cavity region Interior structure is hanging bridge structure D, the structure in the dotted line frame of biasing tie region (i.e. region in Fig. 8 in dashed circle) To form the hanging bridge structure D needed for bias junctions.
For the ease of by the forming process of bias junctions, the synchronous progress of forming process with transmiting intracavitary Josephson junction, Fig. 8 Middle bias junctions both sides need to reserve white space, in order to the progress of follow-up double-deck oblique angle evaporation technology, in Fig. 5 a Biasing for junction structure, white space that bias junctions both sides reserve is respectively the region of the first connecting line 43, and second The region of connecting line 44, for the biasing junction structure in Fig. 5 b, the white space that bias junctions both sides reserve is respectively The region of first connecting line 43, and the region of the 4th connecting line 46.Below only by taking the biasing junction structure in Fig. 5 b as an example Illustrate, for the biasing junction structure in Fig. 5 a, the two is differed only in, and the second connecting line 44 and bias junctions in Fig. 5 a are same When formed, and the 4th connecting line 46 in Fig. 5 b is formed simultaneously with bias junctions, the 5th connecting line 47, the 3rd connecting line 45 and metal Layer is formed in same etching process.
Due to the 5th connecting line 47 and the 3rd connecting line 45 due to being etched in metal level during formed, because Double-layer photoetching glue-line in this Fig. 8 need to cover the surface of the 5th connecting line 47 and the 3rd connecting line 45, in case subsequent technique is to two The influence of person's shape.
The mode of first photoresist layer 70 and the second photoresist layer 71 is shown in Fig. 8, is merely to illustrate the first photoresist layer 70 are located at the lower section of the second photoresist layer 71, can not be used to illustrating the first photoresist layer 70 and the spin coating of the second photoresist layer 71 Scope is variant.
Specifically, as Figure 8-Figure 10, Fig. 9 is the cross-sectional view that the hanging bridge structure D in Fig. 8 is cut along AA ', Figure 10 is the cross-sectional view that the hanging bridge structure D in Fig. 8 is cut along BB '.
After transmission cavity region and biasing tie region spin coating the first photoresist layer 70 and the second photoresist layer 71, using throwing The photoetching technique such as shadow photoetching technique or laser writing technology or electron beam exposure so that after exposing and developing, transmit alveolus The first photoresist layer 70 at hanging bridge structure D regions in domain is removed, the second photoresist layer 71 has been retained, clear area The first photoresist 70 and the second photoresist 71 at domain 22 are retained, the first photoresist layer at the region of conducting interval structure 23 70 and second photoresist layer 71 be all removed, while the region in addition to chamber is transmitted is also by the first photoresist 70 and the second photoresist 71 coverings, in case subsequent technique impacts to the structure formed before step S4.
As illustrated in figures 14-16, Figure 14 is the enlarged drawing that tie region is biased in Fig. 8, and Figure 15 is the biasing tie region edge in Fig. 8 The cross-sectional view of AA ' cuttings, Figure 16 are the cross-sectional view that the biasing tie region in Fig. 8 is cut along BB '.
After biasing tie region, exposure imaging, hanging bridge structure D, i.e. hanging bridge structure D are formed at bias junctions region First photoresist layer 70 of lower section is removed, the second photoresist layer 71 has been retained, and two positioned at bias junctions A-A ' directions The first photoresist 70 and the second photoresist 71 of side are retained, and the positioned at the first connecting line 43 and the region of the 4th connecting line 46 One photoresist 70 and the second photoresist 71 are removed, the first photoetching positioned at the 5th connecting line 47 and the region of the 3rd connecting line 45 The photoresist 71 of glue 70 and second is retained.
It should be noted that for different photoetching techniques, different photoresists need to be selected, and according to the spy of photoetching technique Point determines whether to use mask plate, and selects which kind of mask plate, for example, for projection lithography technology, reversion can be selected Photoresist and positive photoresist form the first photoresist layer and the second photoresist layer respectively, and halftoning can be used in exposure process Mask plate.The structure formed after photoetching is only limited in the present embodiment as Figure 8-Figure 10, for being formed shown in figure Hanging bridge structure used in technique be not specifically limited.
It should be noted that in the present embodiment, formd along the length direction along transmission cavity region be arranged in order it is more Individual hanging bridge structure D, to form multiple SQUID structures.Wherein, the hanging bridge structure D is removed by the first photoresist layer 70 of bottom The second photoresist layer 71 afterwards is formed.In Fig. 9, between two hanging bridge structure D, by the first photoresist layer 70 and the second photoetching The region that glue-line 71 covers is the white space 22 in Fig. 2 between two Josephson junctions.
After hanging bridge structure D is formed, using double-deck oblique angle evaporation technique, using two different angles in transmission alveolus The surface of substrate 1 in domain forms Josephson junction, and bias junctions 5 are formed on the surface of substrate 1 of biasing tie region.Specifically, with transmission The double-deck oblique angle evaporation technique is illustrated exemplified by cavity region, the connecting line 43 of bias junctions 4 and first, the 4th connecting line 46 also exist Formed simultaneously during being somebody's turn to do, specific formation process mutually refers to, and repeats no more here.Also, after bias junctions are formed, remove After 5th connecting line 47 and first photoresist 70 and the second photoresist 71 in the region of the 3rd connecting line 45, the 4th connecting line 46 is taken It is connected on the 5th connecting line 47, forms structure as shown in Figure 5 b.
As shown in figure 11, using hanging bridge structure D as mask, do not covered using the first incident angle α 1 by the first photoresist layer 70 On the surface of the substrate 1 of lid, the first superconducting layer 211 is formed.Then, the oxygen argon mixture gas in situ for being passed through certain air pressure, with right The surface of first superconducting layer 211 is aoxidized, that is, obtains insulating barrier 212, as shown in figure 12.Afterwards, as shown in figure 13, with hanging bridge Structure D is mask, using the second incident angle α 2 in the surface of substrate 1, the second superconducting layer 213 of formation.Alternatively, the first superconducting layer 211 and second superconducting layer 213 be metallic aluminum, insulating barrier 212 is alumina layer.
By above step, i.e. Josephson's tie region below hanging bridge structure D, formed exhausted by the first superconducting layer 211/ The sandwich structure that the superconducting layer 213 of edge layer 212/ second is formed, obtains Josephson junction 21.Forming the same of Josephson junction 21 When, in the region of conducting interval structure 23, superconducting metal can also be deposited, as shown in figure 13, the partially electronically conductive region of spacer structure 23 Only the 3rd superconducting layer metal material, the partially electronically conductive region of spacer structure 23 are then the first superconducting layer metal material and insulating barrier material Expect the laminated construction formed, the partially electronically conductive region of spacer structure 23 is then the first superconducting layer metal material, insulating layer material and the The laminated construction that three superconducting layer metal materials are formed.On transmission cavity length direction, conducting interval structure 23 is located at hanging bridge structure D Both sides, two Josephson junctions 21 that two hanging bridge structure D of same SQUID structures 20 are correspondingly formed pass through conducting interval structure 23 is in parallel, and different SQUID structures 21 are connected by conducting interval structure 23 therebetween.
During transmission intracavitary Josephson junction formed above, while it also form the Josephson junction of bias junctions 4.
Step S5：After the preparation of Josephson junction of transmission chamber 2 and bias junctions 4 is completed, the first photoresist layer is removed 70 and second photoresist layer 71, complete the processing of transmission chamber 2 and bias junctions 4.
Step S6：It will be understood by those skilled in the art that low-temperature microwave source chip be batch production, therefore, also need by The substrate for completing process above step carries out scribing cutting, so as to obtain microwave source chip as shown in Figure 1 independent one by one.
Low-temperature microwave source core piece preparation method provided by the present invention, due to formation transmission chamber working frequency by The total capacitance and total inductance of SQUID chains determine, and the total inductance of SQUID chains changes with the change of magnetic field size, magnetic field it is big The change of size of current in the small line with direct current biasing and change, therefore, can by the size of current of regulation direct-current bias line come The resonant frequency of regulation transmission chamber, and then the output frequency of low-temperature microwave source chip can be adjusted, meet quantum chip to microwave The demand of source frequency.
Also, the preparation method of low-temperature microwave source chip disclosed in the present embodiment, exposed using ultraviolet photolithographic, electron beam What the procedure technique such as light, magnetron sputtering plating, reactive ion etching obtained.The low-temperature microwave source chip is taken up space due to it Small, without special process, and its manufacture craft can be compatible with the manufacture craft of quantum chip, it is possible to which the low temperature is micro- The manufacturing process of wave source chip is directly integrated into the manufacture craft of quantum chip, so that by the low-temperature microwave source chip to quantum Bit carries out manipulation in situ.Further, since need not be from ambient delivery microwave signal, therefore eliminate whole from room temperature to low temperature Bar high frequency cable and subsidiary numerous and diverse filtering, decay design, significantly simplify current quantum chip control system for signal The requirement of number of, lines, the integrated of quantum bit is easily facilitated, there is facilitation to further expanding quantum chip-scale.
Another embodiment of the present invention discloses a kind of low-temperature microwave source, and its circuit structure diagram is as shown in figure 17, and the low temperature is micro- Wave source includes the low-temperature microwave source chip 100 and control circuit described in above example, and the control circuit is used for be described low Temperature microwave source chip applies operating voltage, it is generated and transmitted by microwave photon.
Wherein, the control circuit includes constant-current source 81, and is connected with the voltage bias line of low-temperature microwave source chip 100 Mu balanced circuit；
The constant-current source 81 is used to provide power input for the mu balanced circuit；
The mu balanced circuit is used to provide stable bias voltage for the bias junctions in the low-temperature microwave source.
It should be noted that in the course of work, low-temperature microwave source chip is arranged under low temperature environment, and the low-temperature microwave source Bias voltage needed for chip is then arranged under room temperature environment from constant-current source, i.e. constant-current source 81 at room temperature, therefore, in order to incite somebody to action The voltage for coming from the constant-current source under room temperature environment is transferred on low-temperature microwave source chip, and the mu balanced circuit includes room temperature voltage stabilizing Circuit 80 and low temperature mu balanced circuit 90, the low temperature mu balanced circuit are arranged under identical environment with the low-temperature microwave source chip.
Specifically, as shown in figure 14, room temperature mu balanced circuit 80 includes the first low pass filter electrically connected with constant-current source 81 82, for eliminating under room temperature environment, the voltage pulsation caused by the noise on circuit.
Low temperature mu balanced circuit 90 includes the second low pass filter 91, the first divider resistance R1, the second divider resistance R2 and the One impedance ground element M1.Wherein, the first divider resistance R1 and the second divider resistance R2 is preferably measuring resistance.
Wherein, the second low pass filter 91 electrically connects with first low pass filter 82, for eliminating under low temperature environment, The voltage pulsation caused by the noise on circuit；
First divider resistance R1 and the second divider resistance R2 connect with the voltage bias line 5 on low-temperature microwave source chip.Tool Body is that the first divider resistance R1 first end electrically connects the second divider resistance R2 first end, and the second end connects by described first Ground impedor M1 is grounded, and the second end of the second divider resistance R2 is with the battery lead plate 51 of the voltage bias line 5 by low The metal heat sink electrical connection of temperature microwave source chip bottom.The output end of constant-current source 81 is low by the first low pass filter 82 and second Bandpass filter 91, electrically connected with the first divider resistance R1 first end.
In the course of work, by the battery lead plate 51 of voltage bias line 5, inductance 52, transmission chamber 2 and metal level 6, by constant current After the first divider resistance R1 and the second divider resistance R2, the bias voltage of acquisition is applied to the both ends of bias junctions in source 81.Specifically , the metal level 6 is grounded, i.e. the first end of bias junctions 4, is joined directly together with metal level 6, and is grounded by the metal level 6, And the voltage from constant-current source 81 after the first divider resistance R1, the second divider resistance R2, battery lead plate 51 and inductance 52 through obtaining Stabilization bias voltage, by transmiting chamber 2, bias junctions 4 are transferred to transmiting the second end that is joined directly together of chamber 2, so as to inclined Put the both ends of knot 4 and apply stable bias voltage.Wherein, the first divider resistance R1 and the second divider resistance R2 have partial pressure voltage stabilizing Effect, inductance 52 also have the function that filtering and voltage stabilizing.
In addition, the room temperature mu balanced circuit 80 also includes elements below：
Differential voltage table 85, for detecting the voltage at the second divider resistance both ends；
3rd low pass filter 83 and the 4th low pass filter 84, for eliminating the voltage wave caused by the noise on circuit It is dynamic.
The low temperature mu balanced circuit 90 also includes elements below：
5th low pass filter 92 and the 6th low pass filter 93, for eliminating the voltage wave caused by the noise on circuit It is dynamic；
First electric capacity C1 and the second impedance ground element M2, the second electric capacity C2 and the 3rd impedance ground element M3, for every From the thermal noise on circuit.
Wherein, the first end of the differential voltage table 85 passes through the 3rd low pass filter 83 and the 5th low pass filtered Ripple device 92, it is connected with the first end of the second divider resistance R2, the second end of the differential voltage table 85 passes through the described 4th Low pass filter 84 and the 6th low pass filter 93, it is connected with the second end of the second divider resistance R2；Described first Electric capacity C1 the first pole plate is connected with the first end of the second divider resistance R2, and the second pole plate passes through second impedance ground Element M2 is grounded；The first pole plate of the second electric capacity C2 is connected with the second end of the second divider resistance R2, the second pole plate It is grounded by the 3rd impedance ground element M3.
It was found from the circuit diagram shown in Figure 14, be applied in the voltage bias line voltage U=IR1- [(R1/R2)+ 1] U ', wherein, R1 is the resistance of the first divider resistance R1, and R2 is the resistance of the second divider resistance R2, and I is the perseverance The current value in stream source, U ' are the voltage that differential voltage table 85 measures obtained the second divider resistance R2 both ends.I.e. first Divider resistance R1 and the second divider resistance R2 selection standard resistance, in the case of its resistance is known, applied according in voltage bias line The requirement of the bias voltage added, you can suitable constant-current source is selected, in other words, by selecting different constant-current sources, you can change The size of the bias voltage applied on time variant voltage offset line.
It should be noted that the quantity of first the-the six bandpass filter of low pass filter is at least one in the present embodiment, Do not limited in quantity the present embodiment of low pass filters at different levels, as long as the voltage for eliminating that thermal noise is brought on circuit can be reached The purpose of fluctuation.Also, the wire for being used to connect each circuit element in low temperature mu balanced circuit in the present embodiment is low Warm DC wire, as Lakeshore lines can be selected in the low temperature direct wire in the present embodiment.In addition, for the ease of expanded circuit Extension and different elements compatibility and isolation, each element of the low-temperature microwave source chip and the low temperature mu balanced circuit It may be disposed on same circuit board.
Circuit structure in the present embodiment, made by the first divider resistance R1 and the second divider resistance R2 partial pressure voltage stabilizing With the voltage pulsation caused by thermal noise on circuit being reduced into two to three orders of magnitude.Further, the first electric capacity C1 and Two electric capacity C2 match impedance ground element as isolation capacitance, the thermal noise further isolated on circuit, finally may be used So that the fluctuation range of bias voltage is reduced within 100pV, it is achieved thereby that accurate partial pressure voltage regulation result.
In addition, control circuit also includes the current regulating circuit and DC source being connected with the direct current biasing line.Wherein, institute DC source is stated to be used for the direct current biasing line output current；The current regulating circuit is used to export the DC source to institute The size of current for stating direct current biasing line is adjusted.
DC source in the present embodiment may be disposed at room temperature, and current regulating circuit refers to the setting side of mu balanced circuit Formula, partly it is arranged under room temperature environment, is partly arranged under low temperature environment, also, the current regulating circuit under low temperature environment leads to Low temperature DC wire is crossed, is electrically connected with the metal heat sink of low-temperature microwave source chip bottom, and then electrically connected with direct current biasing line.
The size of current by regulation direct-current bias line in the present embodiment, to control the output frequency in low-temperature microwave source to exist Within 1GHz-10GHz, the structure setting of low-temperature microwave source chip, can make the regulations speed of output frequency hundred nanosecond rank.
Also, by adjusting resistance R1, Yi Ji of the current value I of constant-current source 81, the first divider resistance in the present embodiment The resistance R2 of two divider resistances size, the power output in low-temperature microwave source is can adjust, specifically, low-temperature microwave in the present embodiment The power output in source is can be controlled within -90dBm to -140dBm, and due to transmission chamber, bias junctions and voltage bias line Structure is the setting of three's annexation, can strengthen bias junctions to the full extent with transmiting the stiffness of coupling of chamber, avoid signal from damaging Lose, also, microwave source chip uses superconductor processing and fabricating, greatly reduces circuit loss, while inhibit additional make an uproar Sound, improves the energy conversion efficiency in low-temperature microwave source to the full extent, the energy conversion in low-temperature microwave source in the present embodiment Efficiency is more than 10%.
It should be noted that the power output in low-temperature microwave source is determined by input power and energy conversion efficiency, working During, the energy conversion efficiency in the low-temperature microwave source in the present embodiment is up to more than 10%, power output, is permanent by changing The size of the bias voltage that stream source inputs to bias junctions is adjusted.Specifically, low-temperature microwave source is in the course of the work, it is necessary in electricity Apply constant voltage U on pressure offset line, voltage U in accordance with the above and the relation of the resonant frequency of transmission chamber, i.e. mhf= 2eU.By taking f=10GHz as an example, then U must is fulfilled for U=m × 20.71uV, and this is a minimum magnitude of voltage, and needs accurate To 100nV.
It should be noted that due to most accurately constant pressure source, the fluctuation of its output voltage at room temperature is also left in 3 μ V-5 μ V The right side, even with divider resistance, it can not also ensure the stability of its output voltage, and the stability of constant-current source at room temperature then may be used To reach the 10fA order of magnitude, therefore made in the present embodiment from the mode of high-precision constant-current source collocation low temperature standards resistance For the output of constant pressure source, so as to meet requirement of the low-temperature microwave source chip for bias voltage stability.By perseverance in the present embodiment The stability for the constant pressure source that stream source collocation low temperature standards resistance is formed can reach 10nV precision, and its stability is significantly larger than most Accurately room temperature constant pressure source, the durability requirements of the bias voltage needed for low-temperature microwave source chip can be met.
Apply constant voltage in voltage bias line, the uncle of the electronic library in bias junctions is obtained energy and be converted into microwave light Son, and then the frequency, amplitude and phase of low-temperature microwave source output signal is reached highly stable.However, it is desirable to illustrate , according to microwave signal Frequency Conversion Theory, it is determined that U concrete numerical value when, be not that m value is bigger, power output is bigger.Tool Body, microwave signal conversion process, mainly as caused by the nonlinear characteristic of dielectric constant on microwave signal propagation path. Only single-frequency f microwave signal by when, f can be using frequency conversion as mf, and the process reversible can also occur, corresponding mistake Journey can be understood as the particle that m energy is hf and merge into the particle that single energy is mhf, or the grain that single energy is mhf Son, resolves into the particle that m energy is just all hf just, and wherein h is Planck's constant.The conversion efficiency specifically occurred is by passing The size for broadcasting nonlinear dielectric constant on path determines.M is bigger, and frequency conversion odds P (n) is lower, and the probability is obeyed Poisson distribution.It will be understood by those skilled in the art that can be according to the Frequency Conversion Theory of microwave signal and low-temperature microwave source chip Structure, the size of bias voltage is determined, so as to select suitable constant-current source 81, be not detailed herein.
For example, bias voltage U=50 μ V, electric current I '=2nA on direct current biasing line, energy conversion efficiency are 10%, the power output in the low-temperature microwave source in the present embodiment can reach -110dBm.Although this numerical value is much smaller than current room temperature The output power range of microwave source, but in fact, the microwave signal required for the manipulation of quantum chip is extremely weak, it is contemplated that the amount of highlighting Signal intensity needed for sub- property, and filtering and decay on circuit, the microwave signal power being actually reached on quantum chip Between.Therefore, real output of the present invention covers the demand scope substantially, and the low-temperature microwave source in the present embodiment can Meets the needs of manipulation of quantum chip and quantum calculation.
The low-temperature microwave source includes low-temperature microwave source chip and control circuit, and it is low-temperature microwave source chip that control circuit, which is used for, Apply operating voltage, it is generated and transmitted by microwave photon, wherein, transmission chamber, bias junctions, electricity on the low-temperature microwave source chip Offset line and direct current biasing line etc. are pressed, is made by semiconductor technology, its manufacture craft and the making work of quantum chip Skill is compatible, therefore can be by the low-temperature microwave source chip together with quantum integrated chip, i.e., in the course of work, the low-temperature microwave source Chip is co-located under low temperature environment with quantum chip, so as at low ambient temperatures, be launched by the low-temperature microwave source chip Microwave photon manipulation in situ directly can be carried out to quantum bit, avoid and microwave source applied by room temperature circuit in the prior art A variety of drawbacks.
Each embodiment is described by the way of progressive in this specification, what each embodiment stressed be and other The difference of embodiment, between each embodiment identical similar portion mutually referring to.For device disclosed in embodiment For, because it is corresponded to the method disclosed in Example, so description is fairly simple, related part is said referring to method part It is bright.
The foregoing description of the disclosed embodiments, professional and technical personnel in the field are enable to realize or using the present invention. A variety of modifications to these embodiments will be apparent for those skilled in the art, as defined herein General Principle can be realized in other embodiments without departing from the spirit or scope of the present invention.Therefore, it is of the invention The embodiments shown herein is not intended to be limited to, and is to fit to and principles disclosed herein and features of novelty phase one The most wide scope caused.

Claims (31)

1. a kind of low-temperature microwave source chip, it is characterised in that transmission chamber, biasing including substrate and on substrate surface Knot, voltage bias line and direct current biasing line；
Wherein, the transmission chamber is used to launch microwave photon, and the transmission chamber includes SQUID chains, and the SQUID chains include multiple SQUID structures, the multiple SQUID structures are serially connected；
The bias junctions electrically connect with the transmission chamber, for producing microwave photon；
The voltage bias line is used to apply bias voltage for the bias junctions, passes through the electronics Cooper pair in the bias junctions The mode of stimulated emission, is converted into microwave photon；
The direct current biasing line is used to apply magnetic field for the transmission chamber；
Wherein, the resonant frequency of the transmission chamber is determined by the total capacitance and total inductance of the SQUID chains；The SQUID chains Total inductance changes with the change of the magnetic field size, the size in the magnetic field with size of current in the direct current biasing line change Change and change.
2. low-temperature microwave source chip according to claim 1, it is characterised in that the total inductance of the transmission chamber is more than described The total inductance of bias junctions so that the electronics Cooper pair constant pressure bias in the case of, by being generated or absorbed by a photon, i.e., The bias junctions can be tunneled through.
3. low-temperature microwave source chip according to claim 2, it is characterised in that the microwave photon is from the transmission chamber Emission rate when launching, less than the tunneling rates that the electronics Cooper pair is tunneled through the bias junctions, so that described Microwave photon is absorbed, to promote the electronics Cooper pair next time by the electronics Cooper pair again before launching Tunnelling, with lasting generation microwave photon.
4. low-temperature microwave source chip according to claim 3, it is characterised in that the SQUID structures are two in parallel The cyclic structure that Josephson junction is formed；
The Josephson junction includes the first superconducting layer, insulating barrier and the second superconducting layer for being sequentially located at the substrate surface.
5. low-temperature microwave source chip according to claim 4, it is characterised in that the direct current biasing line includes strip Electrode strip, the long side of the electrode strip be arranged in parallel with the SQUID chains.
6. low-temperature microwave source chip according to claim 5, it is characterised in that the substrate surface except it is described transmission chamber, Outside bias junctions, voltage bias line and direct current biasing line, in addition to metal level, the metal level surrounds the transmission chamber, partially Knot, voltage bias line and direct current biasing line are put, and the metal level, the voltage bias line and the direct current biasing line exist Formed in same photoetching process；
The transmission chamber positioned at the metal level of its both sides and the direct current biasing line with forming coplanar waveguide structure respectively；
The direct current biasing line and the metal level around it form coplanar waveguide structure.
7. low-temperature microwave source chip according to claim 6, it is characterised in that Josephson junction is become in the biasing.
8. low-temperature microwave source chip according to claim 7, it is characterised in that one end of the bias junctions and the transmission The output end of chamber is joined directly together, and the other end is joined directly together with the metal level.
9. low-temperature microwave source chip according to claim 8, it is characterised in that the formation direction of the bias junctions with The formation direction of Josephson junction is consistent in SQUID chains transmission chamber, so that the bias junctions and the SQUID chains are in same technique Formed in step.
10. low-temperature microwave source chip according to claim 9, it is characterised in that the bias junctions and the transmission chamber The connected mode of output end is：In the transmission chamber long side and close to the position of the transmission chamber output end, extend strip Conductive material directly contacted with the first side of the bias junctions as the first connecting line, first connecting line；
The bias junctions and the connected mode of the metal level are：Extend the conduction of strip on the second side of the bias junctions Material extends upward the conductive material of strip as in metal level as the second connecting line towards the side of the bias junctions Three connecting lines, second connecting line is joined directly together with the 3rd connecting line, and the angle of the two is right angle, the bias junctions First be along relative two sides in the transmission cavity length direction while with second.
11. low-temperature microwave source chip according to claim 10, it is characterised in that first connecting line, described second Connecting line is formed with the bias junctions in same processing step；3rd connecting line walks with the metal level in same technique Formed in rapid.
12. low-temperature microwave source chip according to claim 9, it is characterised in that the bias junctions and the transmission chamber The connected mode of output end is：In the transmission chamber long side and close to the position of the transmission chamber output end, extend strip Conductive material directly contacted with the first side of the bias junctions as the first connecting line, first connecting line；
The bias junctions and the connected mode of the metal level are：Extend the conduction of strip on the second side of the bias junctions Material extends upward the conductive material of strip as in metal level as the 4th connecting line towards the side of the bias junctions Three connecting lines, in the conductive material conduct that the side of afterbody towards the 4th connecting line of the 3rd connecting line extends upward 5th connecting line, the 4th connecting line is overlapped with the 5th connecting line, and the 3rd connecting line is connected with the described 5th The angle of line is right angle, and the first of the bias junctions be along relative two sides in the transmission cavity length direction while with second.
13. low-temperature microwave source chip according to claim 12, it is characterised in that first connecting line, the described 4th Connecting line is formed with the bias junctions in same processing step, the 3rd connecting line, the 5th connecting line and the gold Category layer is formed in same processing step.
14. low-temperature microwave source chip according to claim 8, it is characterised in that the voltage bias line includes battery lead plate, And the inductance around the battery lead plate, the first end of the inductance is directly connected with the battery lead plate, the second end with it is described Chamber is penetrated to be connected.
15. low-temperature microwave source chip according to claim 14, it is characterised in that the transmission chamber is half-wavelength resonance Chamber, the center of the transmission chamber be voltage node, the second end of the inductance directly with the center for transmiting chamber It is connected.
16. low-temperature microwave source chip according to claim 14, it is characterised in that it is described transmission chamber output end with it is described Second coupled capacitor C2 of the first coupled capacitor C1 of metal interlevel and input and the metal interlevel of the transmission chamber it Between relation be C1：C2≥10:1, the microwave photon is proportional to C1 from the speed Ω of the output end transmitting of the transmission chamber2。
17. low-temperature microwave source chip according to claim 16, it is characterised in that it is described transmission chamber resonant frequency f with The constant pressure U applied in the voltage bias line meets relational expression mhf=2eU, wherein, m is positive integer, and h is Planck's constant, e For the electricity of an electronics；Wherein, the resonant frequency of the transmission chamber is equal to the output frequency in the low-temperature microwave source.
18. low-temperature microwave source chip according to claim 17, it is characterised in that the total inductance L=L of the transmission chamber0+ nLj/ 2, the total capacitance C=nc+cj of the transmission chamber, resonant frequencyWherein, LjFor single Josephson junction Inductance, L0For the inductance between the SQUID chains and the metal level, c is between single SQUID structures and the metal level Electric capacity, cj are the SQUID chains electric capacity of itself, and n is the quantity of the SQUID structures on the SQUID chains.
19. low-temperature microwave source chip according to claim 1, it is characterised in that the transmission chamber, the bias junctions, institute The material for stating voltage bias line, the direct current biasing line and the metal level is low temperature superconducting material.
20. low-temperature microwave source chip according to claim 19, it is characterised in that the metal level, the voltage bias The material of line and the direct current biasing line is aluminium or niobium or niobium nitride or titanium niobium nitride.
21. low-temperature microwave source chip according to claim 20, it is characterised in that the transmission chamber and the bias junctions Material is aluminium.
22. low-temperature microwave source chip according to claim 1, it is characterised in that also include deviating from institute positioned at the substrate The laminated metal heat sink of metal is stated, to be radiated to the low-temperature microwave source chip.
23. a kind of low-temperature microwave source, it is characterised in that including the low temperature described in control circuit and claim any one of 1-19 Microwave source chip, the control circuit are used to apply operating voltage for the low-temperature microwave source chip, are generated and transmitted by it micro- Glistening light of waves；
Wherein, the control circuit includes constant-current source, and the mu balanced circuit being connected with the voltage bias line；
The constant-current source is used to provide power input for the mu balanced circuit；
The mu balanced circuit is used to provide bias voltage for the bias junctions in the low-temperature microwave source；
Wherein, the constant-current source is arranged under room temperature environment, and the low-temperature microwave source chip is arranged under low temperature environment, described steady Volt circuit includes room temperature mu balanced circuit and low temperature mu balanced circuit, and the low temperature mu balanced circuit is set with the low-temperature microwave source chip Under identical environment.
24. low-temperature microwave source according to claim 23, it is characterised in that the room temperature mu balanced circuit includes and the perseverance First low pass filter of stream source electrical connection, for eliminating the voltage pulsation caused by the noise on circuit；
The low temperature mu balanced circuit includes：
The second low pass filter electrically connected with first low pass filter, it is electric caused by the noise on circuit for eliminating Pressure fluctuation；
First divider resistance, the second divider resistance and the first impedance ground element, first divider resistance and the second partial pressure electricity Resistance is connected with the voltage bias line, and the first end of first divider resistance electrically connects the first end of the second divider resistance, the Two ends are grounded by the first impedance ground element, the second end of second divider resistance and the electricity of the voltage bias line Pole plate electrically connects, in the course of work, the metal level ground connection；
The output end of the constant-current source is by the first low pass filter and the second low pass filter, with first divider resistance First end electrically connects,, will by the inductance of the voltage bias line, the transmission chamber and the metal level in the course of work The bias voltage that the constant-current source provides is applied to the both ends of bias junctions.
25. low-temperature microwave source according to claim 24, it is characterised in that the room temperature mu balanced circuit also includes：
Differential voltage table, for detecting the voltage at the second divider resistance both ends；
3rd low pass filter and the 4th low pass filter, for eliminating the voltage pulsation caused by the noise on circuit；
The low temperature mu balanced circuit also includes：
5th low pass filter and the 6th low pass filter, for eliminating the voltage pulsation caused by the noise on circuit；
First electric capacity and the second impedance ground element, the second electric capacity and the 3rd impedance ground element, the heat in isolation circuit Noise；
Wherein, the first end of the differential voltage table is by the 3rd low pass filter and the 5th low pass filter, with The first end of second divider resistance is connected, and the second end of the differential voltage table passes through the 4th low pass filter and institute The 6th low pass filter is stated, is connected with the second end of second divider resistance；First pole plate of first electric capacity with it is described The first end of second divider resistance is connected, and the second pole plate is grounded by the second impedance ground element；Second electric capacity First pole plate is connected with the second end of second divider resistance, and the second pole plate is grounded by the 3rd impedance ground element；
Voltage U=IR1- [(R1/R2)+1] U ' being applied in the voltage bias line, wherein, R1 is first partial pressure electricity The resistance of resistance, R2 are the resistance of second divider resistance, and I is the current value of the constant-current source, and U ' is second partial pressure electricity Hinder the voltage at both ends.
26. low-temperature microwave source according to claim 25, it is characterised in that the logical filter of first low pass filter-the six The quantity of ripple device is at least one, and the wire for being used to connect each circuit element in the low temperature mu balanced circuit is that low temperature is straight Conductance line, the low-temperature microwave source chip are arranged on same circuit board with the low temperature mu balanced circuit.
27. low-temperature microwave source according to claim 23, it is characterised in that the control circuit also includes and the direct current Offset line connected current regulating circuit and DC source；
The DC source is used for the direct current biasing line output current；
The current regulating circuit is used to export the DC source to the size of current of the direct current biasing line to be adjusted.
28. low-temperature microwave source according to claim 23, it is characterised in that the output frequency in the low-temperature microwave source exists Within 1GHz-10GHz, the regulations speed of output frequency hundred nanosecond rank, power output within -90dBm to -140dBm, Energy conversion efficiency is more than 10%.
29. a kind of low-temperature microwave source chip preparation method, it is characterised in that for making described in claim any one of 1-20 Low-temperature microwave source chip, including：
Substrate is provided；
Metal level is formed over the substrate；
In same processing step, remove transmission cavity region and bias whole metal levels of tie region, and remove voltage bias line Region and the partial metal layers in direct current biasing line region, to form the voltage bias line and the direct current biasing line, and in institute The both ends for stating transmission cavity region form input and output end, and the output end is located at close to the side of the biasing tie region；
In same processing step, the transmission chamber for including SQUID chains is formed in the substrate surface of the transmission cavity region, and in institute The substrate surface for stating biasing tie region forms bias junctions.
30. low-temperature microwave source preparation method according to claim 29, it is characterised in that the voltage bias line includes electricity Pole plate, and the inductance around the battery lead plate, the direct current biasing line includes the electrode strip of strip, described to remove transmission chamber Region and whole metal levels of biasing tie region, and remove the part metals in voltage bias line region and direct current biasing line region Layer, to form the voltage bias line and the direct current biasing line, including：
Photoresist layer is formed in the layer on surface of metal, and the photoresist layer covers the battery lead plate, the inductance and described The electrode strip region of strip, and the transmission cavity region and biasing tie region are exposed, and the inductance and the electrode The metal level of bar periphery certain area；
Using the photoresist layer as mask, the metal layer material not covered by the photoresist layer is etched away；
The photoresist layer is removed, retains the electrode strip of the battery lead plate, the inductance and the strip.
31. according to the method for claim 30, it is characterised in that being formed in the substrate surface of the transmission cavity region includes The transmission chamber of SQUID chains, and bias junctions are formed in the substrate surface of the biasing tie region, including：
In the substrate surface of the transmission cavity region and the substrate surface of the biasing tie region, the first photoresist is sequentially formed Layer and the second photoresist layer；
Development is exposed to first photoresist layer and the second photoresist layer, to form the length along the transmission cavity region Multiple hanging bridge structures that direction is arranged in order, the second photoetching that the hanging bridge structure is removed by the first photoresist layer of bottom Glue-line is formed；
Using the hanging bridge structure as mask, the first superconducting layer is formed in the substrate surface using the first incident angle；
The surface of first superconducting layer is aoxidized, to form insulating barrier；
Using the hanging bridge structure as mask, the second superconducting layer is formed in the surface of insulating layer using the second incident angle；
Wherein, in first superconducting layer, the insulating barrier and the second superconducting layer shape of the hanging bridge structure lower zone Into lamination form the Josephson junction, become the bias junctions in the Josephson that the biasing tie region is formed；Institute State on transmission cavity length direction, the superconduction layer material between adjacent two hanging bridge structures forms conducting interval structure, described Transmit on chamber width, two Josephson junctions positioned at the hanging bridge structure both sides pass through the conducting interval structure respectively Parallel connection forms the SQUID structures, and on the transmission cavity length direction, multiple SQUID structures pass through the conducting interval knot The structure SQUID chains in series.
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CN112307142A (en) * 2020-06-05 2021-02-02 北京沃东天骏信息技术有限公司 Method and device for determining information point in geographic information system and storage medium
CN112703636A (en) * 2018-09-19 2021-04-23 国际商业机器公司 Low-temperature on-chip microwave filter for quantum device
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CN112703636A (en) * 2018-09-19 2021-04-23 国际商业机器公司 Low-temperature on-chip microwave filter for quantum device
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CN116259591B (en) * 2023-05-16 2023-07-07 中诚华隆计算机技术有限公司 Refrigerating method applied to superconducting quantum chip and quantum computing device
CN116596079A (en) * 2023-07-19 2023-08-15 中诚华隆计算机技术有限公司 Quantum computing device for weakening electromagnetic resonance
CN116596079B (en) * 2023-07-19 2023-09-26 中诚华隆计算机技术有限公司 Quantum computing device for weakening electromagnetic resonance
CN117691965A (en) * 2024-02-04 2024-03-12 无锡频岢微电子有限公司 Filter containing half-mode substrate coaxial resonator

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