CN108933663B - Quantum key distribution system of time phase coding and assembly thereof - Google Patents
Quantum key distribution system of time phase coding and assembly thereof Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0852—Quantum cryptography
- H04L9/0858—Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding
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- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/503—Laser transmitters
- H04B10/505—Laser transmitters using external modulation
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- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/516—Details of coding or modulation
- H04B10/54—Intensity modulation
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- H04B10/516—Details of coding or modulation
- H04B10/548—Phase or frequency modulation
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- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0819—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s)
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0852—Quantum cryptography
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Abstract
The invention discloses a pulse light source which is particularly suitable for phase coding and time phase coding and has a simpler structure, a coding device adopting the light source, a corresponding decoding device and a quantum key distribution system based on time phase coding. Meanwhile, the structure of the pulse light source is further improved in the invention, so that the pulse light source can be more efficiently used for encoding and decoding phases and time phases.
Description
Technical Field
The invention relates to the technical field of quantum secret communication, in particular to a quantum key distribution system based on time phase coding and simplification or optimization of a light source, a coding device and a decoding device thereof.
Background
Communication technology is an indispensable key technology for modern society, and has been rapidly developed and is very new and new. Quantum secret communication is an emerging technology with great application prospect in the technical field of communication. As crystals of quantum mechanics, modern communication and modern cryptography, quantum secret communication has incomparable security advantages over classical communication methods. Quantum key distribution is one of the most common and easy to popularize among the many subdivision areas covered by quantum secret communication. The quantum key distribution is based on the basic principle of quantum mechanics, and the information is encrypted by using a one-time-pad mode, so that the characteristic of incapability of deciphering secret communication is ensured in principle, and the method is a great improvement of national defense institutions, financial institutions, government departments and even Internet finance with high confidentiality requirements and high development speed.
Since birth in 1984, the BB84 protocol is developed increasingly as a first set of quantum key distribution protocols, and has become the most widely applied quantum key distribution protocol in the world, the most mature technology and the best comprehensive effect. The BB84 protocol is based on four-state coding, codes information by utilizing a polarization or phase mode, transmits photons subjected to polarization or phase coding in a quantum channel, and decodes the information by a set of simple decoding devices consisting of wave plates, beam splitters, photoelectric cells, corresponding circuits and the like. The system has the advantages of simple structure, low technical requirements on the system, easy maintenance and large-scale production, mature process and incomparable advantages in terms of code rate and code distance compared with other protocols.
The BB84 protocol combined with the decoy scheme can well solve the potential safety hazard of the non-ideal single photon source, and is the scheme which is most widely applied and has the highest practical degree at present. The BB84 coding scheme mainly adopts coding modes such as polarization coding, phase coding, time bit-phase coding and the like. For polarization coding, the polarization coding has the advantages of low cost and simple structure, and the disadvantage that a polarization system is easily influenced by optical fiber polarization disturbance to directly influence the error rate, so that the compensation measures on polarization caused by the error rate cause time waste to reduce or destabilize the code rate.
Compared with polarization coding, the scheme adopting the phase coding mode prepares light pulses through the unequal arm interferometer, the phase difference of front and rear light pulses is used as an information carrier, and the influence of the polarization change of the optical fiber on the phase difference is small, so that the error rate cannot be increased due to the polarization change, and the optical fiber is favorable for long-distance transmission or use in an environment with strong external interference. The disadvantage is that the insertion loss of the receiving end of the traditional phase system is large, resulting in a code rate and the furthest code distance being lower than that of the polarization system.
The time bit-phase coding scheme developed in the above background adopts 2 basis vectors for coding, namely a time basis vector and a phase basis vector.
Fig. 1 shows an encoding apparatus for implementing temporal bit-phase encoding. As shown in fig. 1, the laser pulse output by the light source is passed through the unequal arm MZ interferometer to produce two temporally separated pulse components that are passed into the equal arm interferometer one after the other. The equal-arm interferometer comprises two Phase Modulators (PM), different interference output light intensity and phase results can be obtained by adjusting the relative phase difference of the two phase modulators, and different light intensity and phase results can be modulated by switching modulation voltage values for pulse components arriving at different times. The encoding device in fig. 1 is capable of encoding 3 kinds of basis vectors. For example, when the phase difference of the equal-arm interferometer is 0 and pi, the corresponding output is extinction and bright results, and at the moment, the Z-base vector is coded; when the phase difference is pi/2, -pi/2, pulses are output, and the phase difference between the pulses is determined to be X-base vector encoding or Y-base vector encoding.
Fig. 2 shows another encoding device for implementing temporal bit-phase encoding. As shown in fig. 2, the laser pulse output by the light source produces two temporally separated pulse components via the unequal arm MZ interferometer. To obtain a phase encoding under the X and Y basis vectors, four phases 0, pi/2 and 3 pi/2 are loaded between the two pulse components by a phase modulator, to obtain a time bit encoding under the Z basis vector, the front or rear pulse components are modulated by an Intensity Modulator (IM), respectively, the passing or extinction is controlled, and the front or rear pulse component is retained to obtain a time state |t 0 > or |t 1 >. In the case of X or Y basis vector encoding, the intensity modulator is transparent to 1/2 of both pulse components. The encoding apparatus of fig. 1 and 2 is consistent in encoding principles, since the intensity modulator can be considered an equal arm interferometer.
It follows that in the known coding devices for implementing time bit-phase coding, elements based on the principle of equal-arm interferometers are required to participate in the coding process, and the stability of the time and phase basis vectors, the bit rate and the bit rate are dependent on the stability of such equal-arm interferometer elements. However, the equal-arm interferometer built by the optical fiber cannot guarantee the stability of the interference result due to various influences of the environmental temperature, stress, vibration and the like caused by the phase change, so that the problems of instability, poor extinction ratio and the like of a Z base vector and an X base vector are caused. Therefore, the known encoding device for time bit-phase encoding has disadvantages in terms of base vector stability, bit rate, and stability thereof, and particularly in a severe encoding environment, frequent intensity feedback is required for stabilizing time encoding or phase feedback is required for stabilizing phase encoding, which also results in the need of introducing other feedback devices and structures, which increase the cost of the system, have poor information transmission effect, and thus limit the practical range.
The existing coding device capable of being used for time coding and phase coding simultaneously has the problems of unstable coding and poor extinction ratio, which directly results in low final communication transmission efficiency and limited transmission distance. However, many related documents in the prior art fail to provide a good solution to the problem, even if the structure is simplified or the coding scheme is improved, the overall communication system is optimized, and the final communication effect is improved to a certain extent, but the problem is still stuck in the throat, and the problem is limited.
For example, toshiba corporation has proposed the implementation of pulsed light sources in quantum communication systems using pulsed injection locking techniques. The light source scheme based on the pulse injection locking technology can enable the spectrum performance of the light pulse to be better, improve the interference performance of the coding state and finally improve the coding performance. However, in the scheme disclosed by toshiba corporation, a polarization encoding method is adopted, and this encoding method is affected by the polarization change of the optical fiber during the transmission process, and the deviation needs to be compensated by polarization feedback. In addition, in the pulse light source scheme based on the pulse injection locking technology, the light source outputs light pulses with random phases, and the improvement is only that the spectrum performance of the light pulses is improved, the time jitter phenomenon of the light pulses is reduced, and the final interference effect is enhanced. Such a light source solution does not solve the above-mentioned drawbacks of the encoding device for time bit-phase encoding, but only to a certain extent allows an enhanced interference effect of the light pulses, and the improvement of the efficiency of the overall communication system is still limited.
The inventors' pending published prior application (CN 201611217678.0, which is incorporated herein by reference in its entirety and referred to as "prior application" hereinafter) proposes a pulsed light source structure formed by organically combining injection locking technology with laser tuning technology, see fig. 3A-3D. By means of the light source structure, the time state (Z base vector) with high and stable extinction ratio can be provided, and two pulses with fixed time and phase relation instead of random pulse can be provided for phase coding (X base vector), so that the requirement of time phase coding can be better met.
However, the present inventors have found that the number of optical elements in the pulse light source structure of the prior application is large, the optical path structure thereof is still significantly complex, and there is still a need for improvement in terms of manufacturing and maintenance costs. Furthermore, the inventors have further studied and found that the two pulses under the phase basis vector provided by the pulse light source structure of the prior application have identical polarization directions, and accordingly in the receiving end of phase encoding or time-phase encoding (which includes an unequal arm interferometer), 50% of energy loss is caused by the presence of non-interference components (the case where the former component walks short arm and the latter component walks long arm), resulting in inefficiency of the encoding apparatus employing such pulse light source.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a pulse light source which is particularly suitable for phase coding and time phase coding and has a simpler structure; meanwhile, the structure of the pulse light source is further improved in the invention, so that the pulse light source can be more efficiently used for encoding and decoding phases and time phases.
A first aspect of the invention discloses a light source that can be used for both time encoding and phase encoding. The light source may include a primary laser that outputs a primary laser pulse for forming seed light based on the driving of a primary drive signal provided by a primary drive signal source for a system period; a slave laser which outputs a slave laser pulse in an injection-locked manner under excitation of the seed light based on driving of a slave drive signal supplied from a drive signal source for encoding a signal light pulse; the slave driving signals include first, second and third slave driving signals, and one of the first, second and third slave driving signals is randomly outputted to drive the slave laser in one system period. Wherein, in a system period, the slave laser outputs only one first slave laser pulse driven by the first slave drive signal, and the first slave laser pulse is excited by a pulse portion of one of the master laser pulses at a first time position; in a system period, the slave laser outputs only one second slave laser pulse driven by the second slave drive signal, and the second slave laser pulse is excited by a pulse portion of one of the master laser pulses at a second time position; and in a system period, the slave laser outputs two consecutive third slave laser pulses driven by the third slave drive signal, and the two third slave laser pulses are excited by pulse portions of one of the master laser pulses at a third time position and a fourth time position, respectively.
The light source of the first aspect of the invention may further comprise an optical transmission element and a beam splitting element, and the slave laser comprises a first slave laser and a second slave laser. Wherein the optical transmission element may be arranged to transmit the main laser pulse to the beam splitting element. The beam splitting element may be arranged to split the master laser pulse into the pulse portions of the master laser pulses for the first and second slave lasers, respectively, and to combine the slave laser pulses into one output. And the optical transmission element may be further arranged to output the output from the beam splitting element out of the laser pulses, thereby providing output light pulses of the light source.
Further, the relative delay between the master laser and the slave laser may be arranged such that, within one system period, the two pulse portions into which the master laser pulse is split by the beam splitting element are capable of overlapping one of the third slave laser pulses at different time positions, respectively, when injected into the slave laser.
Further, an adjustable time delay element can be arranged between the slave laser and the beam splitting element.
Preferably, the first time position may be the same as the third time position, and the second time position may be the same as the fourth time position.
Further, the beam splitting element may be a beam splitter.
Further, the beam splitting element may be a polarizing beam splitter, so that the light pulses output by the light source may be used for efficient encoding and decoding.
Still further, the optical transmission element may be a beam splitter, thereby enabling the light source to be more conveniently implemented in an optical chip.
Alternatively, the optical transmission element may be a circulator.
A second aspect of the invention discloses a light source that can be used for both time and phase encoding. The light source may include a primary laser that outputs a primary laser pulse for forming seed light based on the driving of a primary drive signal provided by a primary drive signal source for a system period; a slave laser which outputs a slave laser pulse in an injection-locked manner under excitation of the seed light based on driving of a slave drive signal supplied from a drive signal source for encoding a signal light pulse; the slave driving signals include first, second and third slave driving signals, and one of the first, second and third slave driving signals is randomly outputted to drive the slave laser in one system period. Wherein, in a system period, the slave laser outputs only one first slave laser pulse driven by the first slave drive signal, and the first slave laser pulse is excited by a pulse portion of one of the master laser pulses at a first time position. During a system period, the slave laser outputs only a second slave laser pulse driven by the second slave drive signal, and the second slave laser pulse is stimulated by a pulse portion of the master laser pulse at a second time location. And in a system period, the slave laser outputs two consecutive third slave laser pulses driven by the third slave drive signal, and the two third slave laser pulses are excited by pulse portions of one of the master laser pulses at a third time position and a fourth time position, respectively.
In the light source of the second aspect of the present invention, the slave laser may include a first slave laser and a second slave laser, and the master laser is connected to the first slave laser and the second slave laser through a beam splitter. Wherein the beam splitter may comprise a first port, a second port, a third port and a fourth port and is arranged to split the master laser pulses received at the third port to form the pulse portions at the first port and the second port for outputting the master laser pulses for the first slave laser and the second slave laser, respectively, and to combine the slave laser pulses received at the first port and the second port at the fourth port for outputting all the way outwards to provide output light pulses of the light source.
Further, the relative delay between the master and slave lasers may be arranged such that, within one system period, the two pulse portions into which the master laser pulse is divided by the beam splitter are capable of overlapping one of the third slave laser pulses at different time positions when injected into the slave lasers, respectively.
Further, an adjustable time delay element may be provided between the slave laser and the beam splitter.
Preferably, the first time position may be the same as the third time position, and the second time position may be the same as the fourth time position.
A third aspect of the invention discloses a light source that can be used for both time and phase encoding. The light source may include a primary laser that outputs a primary laser pulse for forming seed light based on the driving of a primary drive signal provided by a primary drive signal source for a system period; a slave laser which outputs a slave laser pulse in an injection-locked manner under excitation of the seed light based on driving of a slave drive signal supplied from a drive signal source for encoding a signal light pulse; the slave driving signals include first, second and third slave driving signals, and one of the first, second and third slave driving signals is randomly outputted to drive the slave laser in one system period; wherein, in a system period, the slave laser outputs only one first slave laser pulse driven by the first slave drive signal, and the first slave laser pulse is excited by a pulse portion of one of the master laser pulses at a first time position; in a system period, the slave laser outputs only one second slave laser pulse driven by the second slave drive signal, and the second slave laser pulse is excited by a pulse portion of one of the master laser pulses at a second time position; and in a system period, the slave laser outputs two consecutive third slave laser pulses driven by the third slave drive signal, and the two third slave laser pulses are excited by pulse portions of one of the master laser pulses at a third time position and a fourth time position, respectively.
The light source of the third aspect of the present invention may further comprise a beam splitter, a first optical transmission element, a second optical transmission element and a polarizing beam splitter, and the slave laser comprises a first slave laser and a second slave laser. Wherein said master laser is connected to said first slave laser and said second slave laser via said beam splitter via said first optical transmission element and said second optical transmission element, respectively, wherein said beam splitter is adapted to split said master laser pulse into said pulse portions of two said master laser pulses; and, the slave laser pulses output by the first slave laser and the second slave laser are transmitted to different ports of the polarizing beam splitter through the first optical transmission element and the second optical transmission element, respectively; and the polarizing beam splitter is arranged to combine the slave laser pulses output by the first slave laser and the second slave laser into one output to provide an output light pulse of the light source.
Further, the relative delay between the master and slave lasers may be arranged such that, within one system period, the two pulse portions into which the master laser pulse is divided by the beam splitter are capable of overlapping one of the third slave laser pulses at different time positions when injected into the slave lasers, respectively.
Further, an adjustable time delay element may be provided between the slave laser and the beam splitter.
Preferably, the first time position may be the same as the third time position, and the second time position is the same as the fourth time position.
The fourth aspect of the present invention also discloses an encoding device capable of performing time encoding and phase encoding simultaneously, which may include any one of the light sources as described above.
Further, the encoding device of the present invention may further comprise a phase modulator for modulating a phase difference between the consecutive two third slave laser pulses and/or an intensity modulator for modulating a relative light intensity between the first slave laser pulse, the second slave laser pulse, and the third slave laser pulse.
The fifth aspect of the present invention also discloses a decoding device applicable to a time phase encoding scheme, which can be suitably used for decoding a time phase encoding transmitted by the above-mentioned encoding device. The decoding device of the present invention may comprise a basis vector selection unit, a time basis vector decoding unit and a phase basis vector decoding unit, wherein the basis vector selection unit is arranged to input the received basis vector pulse to one of the time basis vector decoding unit and the phase basis vector decoding unit according to a preset probability.
Further, the phase basis vector decoding unit may include an unequal arm interferometer.
Still further, the unequal arm interferometer may be a PBS-BS type MZ interferometer that includes a polarizing beam splitter, a beam splitter, and long and short arms therebetween. In order to achieve an efficient decoding of two pulses under phase basis vectors with mutually perpendicular polarization directions, the polarizing beam splitter may be arranged such that the first pulse of the two consecutive pulses under phase basis vectors is transmitted along the long arm and the second pulse is transmitted along the short arm.
The sixth aspect of the invention also discloses a quantum key distribution system based on time phase encoding, which may comprise any one of the light sources described above or any one of the decoding means described above.
Drawings
Fig. 1 schematically shows a prior art encoding device for time bit-phase encoding;
Fig. 2 schematically shows another prior art encoding device for time bit-phase encoding;
FIGS. 3A-3D schematically illustrate the structure of a pulsed light source in a prior application;
fig. 4A schematically illustrates a light source and an encoding device according to a first embodiment of the present invention;
fig. 4B schematically shows a process of forming light pulses in a light source according to a first embodiment of the invention;
FIG. 5A schematically illustrates a light source and encoding apparatus according to a second embodiment of the present invention;
FIG. 6A schematically illustrates a light source and encoding apparatus according to a third embodiment of the present invention; and
Fig. 7 schematically shows a decoding apparatus of the present invention.
Detailed Description
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following examples are provided by way of illustration to fully convey the spirit of the invention to those skilled in the art to which the invention pertains. Thus, the present invention is not limited to the embodiments disclosed herein.
According to the present invention, the light source may include: a main laser which outputs a main laser pulse for forming seed light under the drive of a main drive signal supplied from a main drive signal source; and a slave laser that outputs a slave laser pulse for encoding under the drive of a slave drive signal supplied from a slave drive signal source. The slave driving signal may include first, second, and third slave driving signals, and the slave driving signal source may randomly output one of the first, second, and third slave driving signals. During a system period, the slave laser outputs only a first slave laser pulse driven by a first slave drive signal, and the first slave laser pulse is excited by a pulse portion of the master laser pulse at a first time location. During a system period, the slave laser outputs only a second slave laser pulse driven by a second slave drive signal, and the second slave laser is excited by a pulse portion of the master laser pulse at a second time position. In one system period, the slave laser outputs two consecutive third slave laser pulses driven by a third slave drive signal, and the two third slave laser pulses are excited by pulse portions of one master laser pulse at a third time position and a fourth time position, respectively. Since the seed light used to excite the two third slave laser pulses originates from the two pulse portions of the same master laser pulse, a fixed phase relationship may be formed between the two seed light, so that under an injection locked light emission mechanism, a fixed, rather than random, phase relationship will also be formed between the successive two third slave laser pulses generated by the excitation of the two seed light by the two pulse portions of the same master laser pulse.
In this context, a time position such as a first, second, third or fourth time position may be used to indicate a relative time position within one system cycle.
The light source of the present invention is particularly suitable for time bit-phase encoding, wherein the first and second slave laser pulses may be used for encoding under the Z-basis vector, i.e. temporal encoding; two consecutive third slave laser pulses may be used for encoding under the X-basis vector, i.e. phase encoding. In other words, when performing Z-ary vector encoding, the slave drive signal source may output one of the first and second slave drive signals to cause the slave laser to output a slave laser pulse having a fixed temporal characteristic (e.g., temporally preceding or following) based on the excitation of one master laser pulse for temporal encoding; when performing X-base vector encoding, the slave drive signal source may output a third slave drive signal to cause the slave laser to output two successive slave laser pulses having a stable time and phase relationship based on one master laser pulse to meet the phase encoding requirement.
Preferably, the first and second slave laser pulses may be set to have the same intensity, and the intensity of each of the consecutive two third slave laser pulses may be set to be half of the first and second slave laser pulses. The first time position may be the same as the third time position. The second time position may be the same as the fourth time position.
Those skilled in the art will readily recognize that the slave drive signals may not be limited to the first, second and third slave drive signals, but that there may be other slave drive signals. Accordingly, the output of the slave laser under excitation of one master laser pulse may not be limited to the first, second and third slave laser pulses, but may also output only one slave laser pulse at other time positions, or a plurality of successive slave laser pulses having a stable time and phase relationship.
For a better understanding of the principles of the present invention, fig. 4-6 illustrate several embodiments of the light source of the present invention, taking as an example its application in a time bit-phase encoding scheme. In these embodiments, for illustrative purposes, only the first, second, and third slave drive signals are output from the drive signal source, and the first, third time positions are the same and the second, fourth time positions are the same. However, those skilled in the art will recognize that these embodiments are merely exemplary and are not intended to limit the invention to these embodiments.
Example 1
A first exemplary embodiment of a pulsed light source according to the present invention is shown in fig. 4A, which may comprise one master laser 10, two slave lasers 11 and 12, an optical transmission element 13 and a beam splitting element 14. The first optical transmission element 13 may comprise three ports 1-3 and be arranged to: light entering from port 1 may exit from port 2 and light entering from port 2 may exit from port 3. The beam splitting element 14 may comprise three ports 1-3 and is arranged such that light entering from port 3 may be split into two beams of light output from port 1 and port 2, respectively.
As shown in fig. 4A, the main laser 10 is connected to the port 1 of the optical transmission element 13, the port 2 of the optical transmission element 13 is connected to the port 3 of the beam splitting element 14, and the port 3 of the optical transmission element 13 serves as an output port of the light source. Port 1 and port 2 of beam splitting element 14 are connected to first slave laser 11 and second slave laser 12, respectively. The optical path length from the first laser 11 to the beam splitting element 14 and the optical path length from the second laser 12 to the beam splitting element 14 may be set to be different.
The first optical transmission element 13 may be a circulator or a beam splitter; the beam splitting element 14 may be a beam splitter or a polarizing beam splitter.
In this embodiment, the main laser pulse reaches port 3 of the beam splitting element 14 via port 1 and port 2 of the optical transmission element 13 in sequence, and after splitting by the beam splitting element 14, two main laser pulse portions are formed. The two master laser pulse portions are injected into the first slave laser 11 and the second slave laser 12 at different time positions via ports 1 and 2 of the beam splitting element 14, respectively, to serve as seed light. The first slave laser 11 output slave laser pulse reaches port 2 of optical transmission element 13 via port 1 and port 3 of beam splitting element 14, and finally is output from port 3 of optical transmission element 13. The slave laser pulse output from the second slave laser 12 reaches the port 2 of the optical transmission element 13 through the ports 2 and 3 of the beam splitting element 14, and is finally output from the port 3 of the optical transmission element 13.
As will be more clearly understood in connection with fig. 4B, in this embodiment the master laser pulse will be split into two pulse portions via the beam splitting element 14, which are injected into the respective slave lasers via different optical paths. By adjusting the relative delays of the master and slave lasers such that during a system period one of the two pulse portions of the master laser pulse can overlap one of the slave laser pulses of the first slave laser 11 in a first (third) time position and the other can overlap one of the slave laser pulses of the second slave laser 12 in a second (fourth) time position, a slave laser pulse is generated from the corresponding slave laser excitation in a predetermined time position by injection locking, respectively as seed light. One slave laser pulse of the first slave laser output and one slave laser pulse of the second slave laser output are eventually coupled into one output at the optical transmission element 13, providing the output pulse of the light source.
In this embodiment, the operating frequency of the master laser may be the system frequency and the operating frequency of the slave laser may be the same as the master laser; furthermore, only the width of the master laser pulse is required to be greater than or equal to the width of one slave laser pulse, and the width of the master laser pulse is not required to be able to cover two consecutive slave laser pulses under the X-base vector, so the requirements on the master laser performance are lower.
When Z-base vector encoding is to be performed, one of the first and second slave drive signals is randomly outputted by the slave drive signal source to drive the first or second slave laser such that the first or second slave laser generates one of the first or second slave laser pulses in an injection-locked manner under excitation of the injected master laser pulse portion at the first or second time position, respectively. Thus, the output time of the first or second slave laser pulse corresponds to the first or second time position, respectively. Thus, the first and second slave laser pulses with respectively different output temporal characteristics may be used directly to represent different temporal encodings, e.g. when the light source outputs only the first slave laser pulse in one system period, the first slave laser pulse may be used to represent the phenomenon of light passing at a first temporal location and extinction at a second temporal location, i.e. to represent temporal encoding 1; when the light source outputs only the second slave laser pulse in one system period, the second slave laser pulse can be used to represent the phenomenon of extinction at the first time position and light passing at the second time position, i.e. can be used to represent the time code 0; and vice versa.
When X-base vector encoding is to be performed, a third slave drive signal is output from the drive signal source for one system period such that the first slave laser generates a third slave laser pulse at a third time position under excitation of the injected master laser pulse portion and the second slave laser generates a third slave laser pulse at a fourth time position under excitation of the injected master laser pulse portion, the two third slave laser pulses being coupled into one output at the optical transmission element, thereby providing two consecutive pulses having a predetermined time interval. Since the seed light respectively injected into two slave lasers in one system period is divided into two pulse portions by a main laser pulse through a beam splitter, the two seed lights have identical wavelength characteristics and fixed phase relations, and correspondingly, a fixed phase relation exists between two continuous third slave laser pulses finally output by a light source.
In this embodiment, since the two seed lights are split by the same main laser pulse via the beam splitting element, they will have exactly the same wavelength characteristics. Correspondingly, the wavelength consistency of two continuous third slave laser pulses output by the light source under the X-base vector is better, so that the interference contrast of decoding of the X-base vector in coding and decoding application can be improved, and the decoding error rate of the X-base vector is reduced.
The difference in optical path between the two slave lasers and the beam splitting element may be achieved in various ways, for example by different lengths of optical fibre, or by providing a delay element (e.g. an electrically tunable retarder) on one or both of the optical paths. Preferably, the delay elements may be provided, thereby satisfying the different decoding devices possibly having different time interval requirements, such time interval adjustability enabling a flexible application of the light source to the encoding device corresponding to the various decoding devices.
The light source corresponding to fig. 3D (i.e. fig. 6 of the previous application) adopts a structure of one master laser and two slave lasers as well, but it is easy to notice that two optical transmission elements and two beam splitting elements are needed in the light source structure, and in the light source structure disclosed in this embodiment, only one optical transmission element and one beam splitting element are needed, the number of optical elements is reduced by half, the light path structure is greatly simplified compared with that of the light source, and the complexity and manufacturing and maintenance costs of the light source are greatly reduced. In addition, in the case of selecting the beam splitter as the optical transmission element 13, the entire light source structure can be very conveniently realized in the form of an optical chip, which is advantageous for the integrated design of the light source.
Further, the beam splitting element 14 may preferably take the form of a Polarizing Beam Splitter (PBS). The performance of the light source structure of the present invention will now be described, by way of example, with this option. Assuming that the polarization direction of the PBS14 is HV direction, the polarization direction of the light of the main laser pulse that reaches port 3 of PBS14 via port 2 of optical transmission element 13 is +.. Those skilled in the art will appreciate that the polarization direction of the PBS14 and the polarization direction of the light reaching the port 3 of the PBS14 are not limited thereto, and that only the light input to the PBS is required to provide two outputs at the PBS. Preferably, the two outputs on the PBS may have the same light intensity.
The light polarization directions of the pulse portions of the main laser output from ports 1 and 2 of PBS14 are |v > and |h >, respectively. The light of V > and H > is injected to the slave lasers 11 and 12 through polarization maintaining circuits, respectively. The light polarization directions of the first and second slave laser pulses output by the slave lasers 11 and 12 under injection excitation of the above-described master laser pulse portion will be |v > and |h >, respectively, and the first and second slave laser pulses having such polarization directions will be output from port 3 of PBS 14. The polarization directions of the two slave laser pulses output from the port 3 of the optical transmission element 13 after being coupled by the PBS14 are perpendicular to each other, i.e., |v > and |h >, respectively. Two pulses under the X-basis vector with such polarization directions perpendicular to each other will be able to avoid the 3dB loss due to non-interference components present in a scheme in which Beam Splitter (BS) is employed for beam splitter element 14, thereby achieving efficient phase decoding.
< Example two >
A second exemplary embodiment of a pulsed light source according to the present invention is shown in fig. 5A, which is a further simplification of the light source structure of fig. 4A. The pulsed light source may comprise a master laser 20, two slave lasers 21 and 22 and a beam splitting element 23. As shown in fig. 4A, the beam splitting element 23 may include three ports 1-4. The master laser 20 is connected to port 3 of the beam splitting element 23, ports 1 and 2 of the beam splitting element 23 are connected to the first slave laser 21 and the second slave laser 22, respectively, and port 4 of the beam splitting element 23 serves as an output port of the light source. The optical path length from the first laser 21 to the beam splitting element 23 and the optical path length from the second laser 22 to the beam splitting element 23 may be set to be different. In this embodiment, the beam splitting element 23 is a Beam Splitter (BS), preferably a 50:50 beam splitter.
In the source configuration of fig. 5A, the main laser pulse will enter the beam splitter at port 3 of beam splitter 23 and split into two main laser pulse portions by the beam splitter. The two master laser pulse portions are injected into the corresponding slave lasers 21 and 22 along different optical paths via ports 1 and 2, respectively. By adjusting the relative delays of the master and slave lasers such that during a system period one of the two pulse portions of the master laser pulse can overlap one of the slave laser pulses of the first slave laser 21 in a first (third) time position and the other can overlap one of the slave laser pulses of the second slave laser 22 in a second (fourth) time position, a slave laser pulse is generated from the respective slave laser excitation in a predetermined time position by injection locking as seed light, respectively. One slave laser pulse output from the first slave laser and one slave laser pulse output from the second slave laser are finally output via port 4 of beam splitter 23 and coupled in one path to provide the output pulse of the light source.
In this embodiment, the operating frequency of the master laser may be the system frequency and the operating frequency of the slave laser may be the same as the master laser; furthermore, only the width of the master laser pulse is required to be greater than or equal to the width of one slave laser pulse, and the width of the master laser pulse is not required to be able to cover two consecutive slave laser pulses under the X-base vector, so the requirements on the master laser performance are lower.
Those skilled in the art will readily recognize that in the light source structure shown in fig. 5A, the injection excitation process under Z-basis vector and X-basis vector encoding is similar to that shown in fig. 4, and thus will not be described in detail herein.
Likewise, the difference in optical path between the two slave lasers and the beam splitting element may be achieved in various ways, for example by different lengths of optical fiber, or by providing a delay element (e.g. an electrically tunable retarder) on one or both of the optical paths. Preferably, the delay elements may be provided, thereby satisfying the different decoding devices possibly having different time interval requirements, such time interval adjustability enabling a flexible application of the light source to the encoding device corresponding to the various decoding devices.
Compared with the light source structure shown in fig. 4A in the present application, only one beam splitting element is needed in the light source structure of the embodiment shown in fig. 5A, so that the light path structure is extremely simplified, and the complexity and the manufacturing and maintenance costs of the light source are reduced to the greatest extent. Meanwhile, the light source structure does not have a circulator, so that the light source structure can be conveniently realized in the form of an optical chip, and the integrated design of the light source is facilitated.
Example III
A third exemplary embodiment of a pulsed light source according to the present invention is shown in fig. 6A, which, in comparison with fig. 3D (fig. 6A of the previous application), is replaced by a polarizing beam splitter PBS.
As shown, the light source of this embodiment comprises one master laser 30 and two slave lasers 31, 32. The main laser pulse is split into two pulse portions by a beam splitter 33. These two pulse portions are injected into the first slave laser 31 and the second slave laser 32 via the first optical transmission element 34 and the second optical transmission element 35, respectively, to serve as seed light. The slave laser pulses output from the first slave laser 31 and the second slave laser 32 pass through a first optical transmission element 34 and a second optical transmission element 35, respectively, and are coupled in one path at a polarizing beam splitter 36 as output pulses of a light source to provide signal light pulses, such as for encoding. Since the first and second slave laser pulses are output by reflection and transmission, respectively, in the PBS36, the output first and second slave laser pulses have polarization directions perpendicular to each other. Preferably, the two slave laser pulses coupled out via the PBS36 may have the same light intensity.
In the pulsed light source, when X-base vector encoding is to be performed, a third slave drive signal is output from the drive signal source in one system period such that the first slave laser 31 generates one third slave laser pulse at a third time position under excitation of the injected master laser pulse portion and the second slave laser 32 generates one third slave laser pulse at a fourth time position under excitation of the injected master laser pulse portion, the two third slave laser pulses being coupled into one output at the polarizing beam splitter 36, thereby providing two consecutive pulses having a predetermined time interval. Since the seed light respectively injected into two slave lasers in one system period is divided into two pulse portions by a main laser pulse through a beam splitter, the two seed lights have identical wavelength characteristics and fixed phase relations, and correspondingly, a fixed phase relation exists between two continuous third slave laser pulses finally output by a light source.
When Z-base vector encoding is to be performed, one of the first and second slave drive signals is randomly outputted by the slave drive signal source to drive the first or second slave laser such that the first or second slave laser generates one of the first or second slave laser pulses in an injection-locked manner under excitation of the injected master laser pulse portion at the first or second time position, respectively. Thus, the output time of the first or second slave laser pulse corresponds to the first or second time position, respectively. Thus, the first and second slave laser pulses having respectively different output time characteristics may be used directly
In representing different time codes, for example, when the light source outputs only the first slave laser pulse in one system period, the first slave laser pulse may be used to represent the phenomenon of light passing at the first time position and extinction at the second time position, i.e., may be used to represent time code 1; when the light source outputs only the second slave laser pulse in one system period, the second slave laser pulse can be used to represent the phenomenon of extinction at the first time position and light passing at the second time position, i.e. can be used to represent the time code 0; and vice versa.
Due to the arrangement of the Polarizing Beam Splitter (PBS) 36, the pulsed light source can output such two pulses with polarization directions perpendicular to each other under the X-base vector, so that the 3dB loss caused by the non-interference component existing in the scheme employing the Beam Splitter (BS) can be avoided as well, thereby realizing efficient phase decoding.
In this embodiment, the operating frequency of the master laser may be the system frequency and the operating frequency of the slave laser may be the same as the master laser; furthermore, only the width of the master laser pulse is required to be greater than or equal to the width of one slave laser pulse, and the width of the master laser pulse is not required to be able to cover two consecutive slave laser pulses under the X-base vector, so the requirements on the master laser performance are lower.
The present invention further simplifies and optimizes the structure of the light source of the previous application, and those skilled in the art will recognize that the light source of the present embodiment can be used in time and/or phase coding schemes as well, and is particularly suitable for use in schemes requiring both time and phase coding (such as time bit-phase coding schemes), including but not limited to those based on decoy BB84 protocol, RFIQKD protocol, tristate protocol (Loss-tolet), MDIQKD protocol.
< Coding device >
Another aspect of the invention also proposes a coding device for simultaneous time and phase coding, comprising a light source according to the invention for outputting two adjacent light pulses with a fixed time and phase relationship under the X-basis vector and one of the two adjacent light pulses under the Z-basis vector. Under the decoy BB84 protocol and/or RFIQKD protocol, the encoding apparatus may further comprise a phase modulator for loading a modulation phase between two adjacent light pulses under the X-basis vector. Optionally, the encoding device may further include an intensity modulator for adjusting the total intensity of the two adjacent light pulses under the X-basis vector and the relationship between the intensity of one of the two adjacent light pulses output under the Z-basis vector, and the intensities of the signal state, the decoy state, the vacuum state, etc. to conform to the unbalanced-basis vector and the decoy state encoding scheme.
Compared with the encoding device in the prior art, the encoding device of the invention needs fewer optical elements, has simpler structure and can be used for high-efficiency decoding; meanwhile, the wavelength consistency of the light pulses for coding provided by the light source is better, so that the coding device can have higher code rate and stability.
< Decoding apparatus >
Yet another aspect of the present invention also proposes a decoding device applied to an encoding device comprising the light source of the present invention. As shown in fig. 7, the decoding apparatus may include a base vector selection unit 41, a time base vector decoding unit 42, and a phase base vector decoding unit 43.
The basis vector selection unit 41 may be used to input the basis vector pulse to one of the time basis vector decoding unit 42 and the phase basis vector decoding unit 43 according to a preset probability.
The time base vector decoding unit 42 may include a first photodetector 421 and a time base vector decoding section. The photodetector 421 detects the basis vector pulse, and the time-basis vector decoding unit receives the detection result output from the photodetector 421 and decodes the time-basis vector according to the detection result.
The phase basis vector decoding unit 43 may include an unequal arm interferometer 431, a second photodetector 432, a third photodetector 433, and a phase basis vector decoding section.
The unequal-arm interferometer 431 may be a michelson interferometer or a mach-zehnder (MZ) interferometer, and is configured to cause two consecutive pulses under a phase basis vector to form interference and output an interference result. For example, the unequal arm interferometer 431 can include a first polarization maintaining beam splitting element 4311, a second polarization maintaining beam splitting element 4312, and long and short arms therebetween, wherein the arm length difference between the long and short arms can be set to coincide with the time interval between two consecutive pulses under the phase basis vector.
The second photodetector 432 and the third photodetector 433 detect the interference result output from the unequal arm interferometer 431, and output the detection result. The phase basis vector decoding unit decodes the phase basis vector based on the detection results output from the photodetectors 432 and 433.
In a preferred embodiment of the decoding device, the first beam splitting element 4311 may be a polarizing beam splitter PBS, and the inequality arm interferometer is correspondingly of the polarizing beam splitter-beam splitter (PBS-BS) type. The decoding device of this preferred embodiment is particularly suitable for use with encoding devices employing the light sources of fig. 4A (the preferred embodiment of beam splitting element 14 being a PBS) and fig. 6A. Since the polarization directions of the two consecutive pulses under the X-base vector are perpendicular to each other in the encoding apparatus employing the two light sources described above, in the preferred embodiment, the unequal-arm interferometer may be arranged such that the former pulse of the two consecutive pulses under the X-base vector is transmitted along the long arm and the latter pulse is transmitted along the short arm, thereby avoiding energy loss due to time misalignment, and thus enabling efficient phase decoding.
< Quantum Key distribution System based on time phase encoding >
The invention also provides a quantum key distribution system based on time phase encoding, which can comprise a first one or more of the light source, the encoding device and the decoding device according to the invention.
The foregoing is merely exemplary of the present invention and it should be noted that modifications and variations can be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and variations should also be regarded as being within the scope of the invention.
Claims (23)
1. A light source usable for both time encoding and phase encoding, comprising:
a main laser that outputs a main laser pulse for forming seed light based on driving of a main driving signal supplied from a main driving signal source in one system period;
a slave laser which outputs a slave laser pulse in an injection-locked manner under excitation of the seed light based on driving of a slave drive signal supplied from a drive signal source for encoding a signal light pulse;
The slave driving signals include first, second and third slave driving signals, and one of the first, second and third slave driving signals is randomly outputted to drive the slave laser in one system period; wherein,
The slave lasers comprise a first slave laser and a second slave laser;
In a system period, the first slave laser outputs only one first slave laser pulse under the drive of the first slave drive signal, and the first slave laser pulse is excited by a pulse portion of one of the master laser pulses at a first time position;
In a system period, the second slave laser outputs only one second slave laser pulse driven by the second slave drive signal, and the second slave laser pulse is excited by a pulse portion of one of the master laser pulses at a second time position; and
In a system period, the first and second slave lasers are driven by the third slave drive signal to generate a third slave laser pulse respectively to form two consecutive third slave laser pulses, and the two third slave laser pulses are excited by pulse portions at third and fourth time positions respectively derived from one of the master laser pulses;
the device is characterized by also comprising an optical transmission element and a beam splitting element; and
The optical transmission element is arranged to transmit the main laser pulse to the beam splitting element;
said beam splitting element being arranged to split said master laser pulses into said pulse portions of said master laser pulses for said first slave laser and said second slave laser, respectively, and to combine said slave laser pulses into one output; and
The optical transmission element is further arranged to output the slave laser pulses output by the beam splitting element.
2. The light source of claim 1 wherein the relative delay between the master laser and the first and second slave lasers is set such that, within a system period, the two pulse portions into which the master laser pulse is divided by the beam splitting element are capable of overlapping one of the third slave laser pulses at different time positions when injected into the first and second slave lasers, respectively.
3. The light source of claim 1, wherein an adjustable time delay element is further provided between at least one of the first and second slave lasers and the beam splitting element.
4. The light source of claim 1, wherein the first time position is the same as the third time position and the second time position is the same as the fourth time position.
5. The light source of any one of claims 1-4, wherein the beam splitting element is a beam splitter.
6. The light source of any one of claims 1-4, wherein the beam splitting element is a polarizing beam splitter.
7. The light source of claim 6, wherein the optical transmission element is a beam splitter.
8. The light source of claim 6, wherein the optical transmission element is a circulator.
9. A light source usable for both time encoding and phase encoding, comprising:
a main laser that outputs a main laser pulse for forming seed light based on driving of a main driving signal supplied from a main driving signal source in one system period;
a slave laser which outputs a slave laser pulse in an injection-locked manner under excitation of the seed light based on driving of a slave drive signal supplied from a drive signal source for encoding a signal light pulse;
The slave driving signals include first, second and third slave driving signals, and one of the first, second and third slave driving signals is randomly outputted to drive the slave laser in one system period; wherein,
The slave lasers comprise a first slave laser and a second slave laser;
In a system period, the first slave laser outputs only one first slave laser pulse under the drive of the first slave drive signal, and the first slave laser pulse is excited by a pulse portion of one of the master laser pulses at a first time position;
In a system period, the second slave laser outputs only one second slave laser pulse driven by the second slave drive signal, and the second slave laser pulse is excited by a pulse portion of one of the master laser pulses at a second time position; and
In a system period, the first and second slave lasers are driven by the third slave drive signal to generate a third slave laser pulse respectively to form two consecutive third slave laser pulses, and the two third slave laser pulses are excited by pulse portions at third and fourth time positions respectively derived from one of the master laser pulses;
The method is characterized in that:
the master laser is connected with the first slave laser and the second slave laser through a beam splitter;
The beam splitter comprises a first port, a second port, a third port and a fourth port and is arranged to split the master laser pulses received at the third port to form the pulse portions of the master laser pulses output for the first slave laser and the second slave laser at the first port and the second port, respectively, and to combine the slave laser pulses received at the first port and the second port at the fourth port into one output.
10. The light source of claim 9 wherein the relative delay between the master laser and the first and second slave lasers is set such that, within a system period, the two pulse portions into which the master laser pulse is divided by the beam splitter are capable of overlapping one of the third slave laser pulses at different time positions when injected into the first and second slave lasers, respectively.
11. The light source of claim 9, wherein an adjustable time delay element is further provided between at least one of the first and second slave lasers and the beam splitter.
12. The light source of claim 9, wherein the first time position is the same as the third time position and the second time position is the same as the fourth time position.
13. A light source usable for both time encoding and phase encoding, comprising:
a main laser that outputs a main laser pulse for forming seed light based on driving of a main driving signal supplied from a main driving signal source in one system period;
a slave laser which outputs a slave laser pulse in an injection-locked manner under excitation of the seed light based on driving of a slave drive signal supplied from a drive signal source for encoding a signal light pulse;
The slave driving signals include first, second and third slave driving signals, and one of the first, second and third slave driving signals is randomly outputted to drive the slave laser in one system period; wherein,
The slave lasers comprise a first slave laser and a second slave laser;
In a system period, the first slave laser outputs only one first slave laser pulse under the drive of the first slave drive signal, and the first slave laser pulse is excited by a pulse portion of one of the master laser pulses at a first time position;
In a system period, the second slave laser outputs only one second slave laser pulse driven by the second slave drive signal, and the second slave laser pulse is excited by a pulse portion of one of the master laser pulses at a second time position; and
In a system period, the first and second slave lasers are driven by the third slave drive signal to generate a third slave laser pulse respectively to form two consecutive third slave laser pulses, and the two third slave laser pulses are excited by pulse portions at third and fourth time positions respectively derived from one of the master laser pulses;
the device is characterized by further comprising a beam splitter, a first optical transmission element, a second optical transmission element and a polarization beam splitter: and
The master laser is connected to the first slave laser and the second slave laser through the beam splitter via the first optical transmission element and the second optical transmission element, respectively, wherein the beam splitter is configured to split the master laser pulse into the pulse portions of the two master laser pulses; and, the slave laser pulses output by the first slave laser and the second slave laser are transmitted to different ports of the polarizing beam splitter through the first optical transmission element and the second optical transmission element, respectively; and
The polarizing beam splitter is arranged to combine the slave laser pulses output by the first slave laser and the second slave laser into one output.
14. The light source of claim 13 wherein the relative delay between the master laser and the first and second slave lasers is set such that, within a system period, the two pulse portions into which the master laser pulse is divided by the beam splitter are capable of overlapping one of the third slave laser pulses at different time positions when injected into the first and second slave lasers, respectively.
15. The light source of claim 13, wherein an adjustable time delay element is further provided between at least one of the first and second slave lasers and the beam splitter.
16. The light source of claim 13, wherein the first time position is the same as the third time position and the second time position is the same as the fourth time position.
17. A coding device capable of simultaneous time and phase coding comprising a light source according to any one of claims 1-16.
18. The encoding device of claim 17, further comprising a phase modulator for modulating a phase difference between the consecutive two third slave laser pulses and/or an intensity modulator for modulating a relative light intensity between the first, second, third slave laser pulses.
19. A decoding apparatus for decoding a time-phase code transmitted by an encoding apparatus according to claim 17 or 18, the decoding apparatus comprising a basis vector selection unit, a time basis vector decoding unit and a phase basis vector decoding unit, wherein the basis vector selection unit is arranged to input a received basis vector pulse to one of the time basis vector decoding unit and the phase basis vector decoding unit according to a preset probability.
20. The decoding apparatus of claim 19, wherein the phase basis vector decoding unit comprises an unequal arm interferometer.
21. The decoding apparatus of claim 20, wherein the unequal-arm interferometer comprises a polarizing beam splitter, a beam splitter, and long and short arms therebetween, the polarizing beam splitter being configured such that a first pulse of two consecutive pulses under a phase basis vector is transmitted along the long arm, and a later pulse is transmitted along the short arm.
22. A quantum key distribution system based on time phase encoding comprising the light source of any one of claims 1-16.
23. A quantum key distribution system based on time phase encoding comprising a decoding apparatus as claimed in any one of claims 19 to 21.
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| CN111740823B (en) * | 2020-07-09 | 2021-02-19 | 国开启科量子技术(北京)有限公司 | Time-phase quantum key coding device, system and method |
| CN111934868B (en) * | 2020-08-17 | 2022-11-08 | 中国科学院半导体研究所 | Decoding chip and decoding method for quantum key distribution |
| CN115208471A (en) * | 2021-04-09 | 2022-10-18 | 山东国迅量子芯科技有限公司 | Quantum key distribution optical chip for time phase coding and unequal-arm interferometer optical chip |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106161011A (en) * | 2016-08-19 | 2016-11-23 | 浙江神州量子网络科技有限公司 | A kind of plug and play quantum key dissemination system based on coding time phase and method and transmitting terminal and receiving terminal |
| CN106533676A (en) * | 2016-12-22 | 2017-03-22 | 浙江神州量子网络科技有限公司 | Quantum key distribution system based on reference system independent protocol |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| CN106209361B (en) * | 2016-07-22 | 2019-06-21 | 中国科学技术大学 | A kind of star-like quantum key distribution network still can guarantee safety without credible relaying |
| CN106656344B (en) * | 2017-01-16 | 2023-09-01 | 浙江神州量子网络科技有限公司 | MDI-QKD system and MDI-QKD method |
-
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- 2017-05-26 CN CN201710385772.5A patent/CN108933663B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| CN106533676A (en) * | 2016-12-22 | 2017-03-22 | 浙江神州量子网络科技有限公司 | Quantum key distribution system based on reference system independent protocol |
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