CN109547144A - A kind of clock system and method based on quantum entanglement - Google Patents
A kind of clock system and method based on quantum entanglement Download PDFInfo
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- CN109547144A CN109547144A CN201811649035.2A CN201811649035A CN109547144A CN 109547144 A CN109547144 A CN 109547144A CN 201811649035 A CN201811649035 A CN 201811649035A CN 109547144 A CN109547144 A CN 109547144A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
- H04J3/0644—External master-clock
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- 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
- H04B10/70—Photonic quantum communication
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0682—Clock or time synchronisation in a network by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
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Abstract
The invention discloses a kind of clock system and method based on quantum entanglement, including tangling source unit, transmission unit, clock synchronization unit Alice, clock synchronization unit Bob and measuring unit, the present invention is using the entangled photons of single polarization state as synchronization signal carrier, the automatic compensation that shake is polarized in optical fiber is realized using faraday mirror and two-way approach, the approximate entangled photon pairs of frequency are formed by 790nm laser pump (ing) II type phase-matching crystals, the delay of two optical paths is controlled by electrically controllable optical delay line precision, it obtains synchronizing bipartite HOM recess maximum value to clock, correct time to obtain on the basis of temporary location is poor, realize that the clock of both sides is synchronous by the directly measurement of entangled photons again.
Description
Technical field
The present invention relates to quantum information and technical field of photo communication, more particularly, to it is a kind of based on quantum entanglement when
Clock synchronization system and method.
Background technique
Time (frequency) is one of the most basic physical quantity of people's knowledge of natural environment circle, the 13rd international metering in 1967
In the conference decision International System of Units (SI), chronomere second (S) is defined as:133CSBetween two hyperfine energy levels of atomic ground state
The duration in 9192631770 periods of transition radiation.Because the time is basic physics at present with highest measurement precision
Amount, so other physical quantitys measure again after being usually converted into temporal frequency, such as the definition of length meter is the light in vacuum
The distance passed through in 1/299793458 second time interval.
In the communications field, temporal frequency is a critically important parameter；Time and frequency standard is delivered in high-accuracy time service system
It is also most important in system.Such as in SDH network, it is desirable that necessary whole network equipment clock is synchronous, otherwise will lead to data perturbation, is
System paralysis.But every equipment all has independent clock (crystal oscillator) control, although may be calibrated to for the first time when factory unanimously,
It is because of manufacturing process, the factors such as local environment are different, the increase of runing time at any time, and each clock moving law is different, such as
Calibration is compared in fruit not in time, and each clock operation difference, whole network will will fall into chaos.It is this comparison and
Calibration is exactly that clock is synchronous.Time and Frequency Synchronization technology refers to the time frequency signal that by certain means, the clock in strange land is generated
It is compared, and forms the process of unified time and frequency standards.
Technological achievement of the quantum key distribution as the closest application in quantum information field, by development in more than 30 years, mesh
Before have evolved to the measuring device independent protocol application stage.Measuring device independent protocol is based on Bell state measuring principle, at
Code rate depends on Hong-Ou-Mandal (HOM) effect of photon.And the effect requires the time one of photon arrival HOM interferometer
It causes, otherwise cannot generate interference and lead to error code.The independent light pulse using different wave length general at present using wavelength-division multiplex come
The synchronization for realizing communicating pair, consumes wavelength resource.However the increase of the network user, especially in classical and quantum communications fusion
In network, each wavelength is valuable resource, and the above method is obviously uneconomical also infeasible.
In the prior art, patent 201410337054.7 realizes multi-user using multiple-wavelength laser and wavelength-selective switches
Between quantum key distribution and shared, but do not consider stationary problem, used plug and play scheme do not ensure that as
Safety under time shift attack.
Realize that the thought of time synchronization comes from Giovannetti in 2001 et al. earliest and exists using the method for quantum entanglement
Paper " Quantum-enhanced positioning and clock synchronization " on " nature " magazine.Benefit
It can break through the limit of shot noise with Quantum Entangled States and quantum squeezed state, realize that the even more accurate clock of subpicosecond is same
Step.
Patent 201120311727.3 proposes the time synchronization that big-dipper satellite is realized using quantum entanglement, but photon exists
Decaying in atmosphere is larger, is aligned between satellite and earth station more difficult.
Summary of the invention
The present invention provides a kind of clock system based on quantum entanglement, which realizes quantum using Quantum Entangled States
It is synchronous with the clock in classical converged network.
Another object of the present invention is to provide a kind of clock synchronizing method based on quantum entanglement.
In order to reach above-mentioned technical effect, technical scheme is as follows:
A kind of clock system based on quantum entanglement, including sequentially connected tangle source unit, transmission unit, synchronization
Unit Alice, Bob and measuring unit；The source unit that tangles includes sequentially connected pump light, nonlinear crystal, first
Narrow band filter and the second narrow band filter；The transmission unit includes sequentially connected first polarization beam apparatus, the second polarization
Beam splitting, controllable optical delay line, manual variable optical delay line, the first optical fiber link and the second optical fiber link；Clock synchronization unit
Alice includes sequentially connected third narrow band filter, the first beam splitter, the first faraday mirror, the first optoisolator and first
Single-photon detector；Clock synchronization unit Alice includes sequentially connected 4th narrow band filter, the second beam splitter, the second method
Draw mirror, the second optoisolator and the second single-photon detector；The measuring unit includes sequentially connected 5th narrow-band filtering
Device, the 6th narrow band filter, the first Polarization Controller, the second Polarization Controller, third beam splitter, third single-photon detector,
4th single-photon detector and coincidence counting device.
Preferably, the pump light is pulse or continuous wave laser.
Preferably, the pump light Output of laser wavelength is 790nm.
Preferably, the nonlinear crystal is Type II PPKTP crystal.
A kind of clock synchronizing method based on quantum entanglement, comprising the following steps:
S1, system initialization: source unit, transmission unit, measuring unit and clock synchronization unit Alice, Bob are tangled in inspection
Hardware facility, check whether equipment runs well, set primary condition；
S2, optical path coarse adjustment: manually adjusting the length of fibre delay line, guarantees measuring unit to clock synchronization unit Alice
It is equal roughly with the distance of clock synchronization unit Bob；
S3, optical path fine tuning: controllable optical delay line time delay is arranged in transmission unit, and measuring unit passes through measurement entangled photon pairs
Interference obtains photon count value；
S4, it finds HOM effect maximum value: repeating S3 more times, Step wise approximation HOM interference fringe maximum value；
S5, after S4 obtains maximum value, Alice and Bob calibrate local clock by respective single-photon detector；
S6, timing repeat S3~S5, realize the real-time synchronization of clock.Compared with prior art, the technology of the present invention side
The beneficial effect of case is:
1. the present invention is carried out using the entangled photons of single polarization state, fiber bit clock is synchronous, and avoiding polarization mode dispersion causes
Accuracy decline, reduce the single-photon detector quantity of needs；
2. the faraday mirror that the present invention uses can realize the automatic compensation for polarizing shake in optical fiber link, reduces optical fiber and answer
Power acts on the influence to photon transmission, improves interference to comparison；3. the present invention interferes effect using the HOM based on entangled photon pairs
It answers, clock synchronization accuracy can be improved.
Detailed description of the invention
Fig. 1 is the working principle of the invention figure；
Fig. 2 is the structural schematic diagram for tangling source unit；
Fig. 3 is the structural schematic diagram of transmission unit；
Fig. 4,5 be the structural schematic diagram of clock synchronization unit；
Fig. 6 is the structural schematic diagram of measuring unit；
Fig. 7 is the schematic diagram of the embodiment of the present invention；
Fig. 8 is work flow diagram of the invention.
The corresponding title of each component in figure:
Tangle source unit -1 ', pump laser -101, nonlinear crystal -102, the first narrow band filter -103, the second is narrow
Band filter -104；
Transmission unit -2 ', the first polarization beam apparatus -201, the second polarization beam apparatus -202, electrically controllable optical delay line -203,
Manual variable optical delay line -204, the first optical fiber link -205, the second optical fiber link -206；
Clock synchronization unit Alice-3 ', third narrow band filter -301, the first beam splitter -302, the first faraday mirror -
303, first optoisolator -304, the first single-photon detector -305；
Clock synchronization unit Bob-4 ', the 4th narrow band filter -401, the second beam splitter -402, the second faraday mirror -
403, second optoisolator -404, the second single-photon detector -405；
Five narrow band filter -501, the of measuring unit -5 ', the, six narrow band filter -502, the first Polarization Controller -503,
Second Polarization Controller -504, third beam splitter -505, four single photon detection -507 of third single-photon detector -506, the, symbol
Total number device -508.
Specific embodiment
The attached figures are only used for illustrative purposes and cannot be understood as limitating the patent.
In order to better illustrate this embodiment, the certain components of attached drawing have omission, zoom in or out, and do not represent actual product
Size；
To those skilled in the art, it is to be understood that certain known features and its explanation, which may be omitted, in attached drawing
's.
The following further describes the technical solution of the present invention with reference to the accompanying drawings and examples.
If Fig. 1-7 shows, a kind of clock system based on quantum entanglement, including tangle source unit 1 ', transmission unit 2 ',
Clock synchronization unit Alice3 ', clock synchronization unit Bob-4 ' and measuring unit 5 '.Connected between described each unit by optical fiber
It connects, in which:
The source unit 1 ' that tangles includes pump laser 101, nonlinear crystal 102, the first narrow band filter 103, and
Two narrow band filters 104；Pump laser 101 is the laser that wavelength is 790nm, for generating pumping laser, the pumping
Laser 101 can produce signal photon and idler photon two-way entangled photons pulse；102 reception pattern of nonlinear crystal is matched
Wavelength generates the entangled photon pairs of frequency entanglement by parametric down conversion (Parametric Downconversion)；It is wherein non-
Linear crystal 102 is the PPKTP crystal of TypeII type.
The transmission unit 2 ' includes the first polarization beam apparatus 201, the second polarization beam apparatus 202, electrically controllable optical delay line
203, manual variable optical delay line 204, the first optical fiber link 205 and the second optical fiber link 206；First polarization beam apparatus 201 connects
It receives from the signal photon for tangling source unit, transmission level polarised light enters electrically controllable optical delay line 203, electrically controllable optical delay line
203 are then transferred to clock by the first optical fiber link 205 by PC control, accurate control delay (resolution ratio is up to 1fs)
Synchronization unit Alice3 '；Second polarization beam apparatus 202 is received from the idler photon for tangling source unit 1 ', transmission level polarization
Light enters manual variable optical delay line 204, is transmitted to clock synchronization unit Bob4 ' by the second optical fiber link 206.
The clock synchronization unit Alice3 ' includes third narrow band filter 301, the first beam splitter 302, the first faraday
Mirror 303, the first optoisolator 304, the first single-photon detector 305；Third narrow band filter 301, which receives, comes from transmission unit 2 '
Signal photon, filter stray light after enter the first beam splitter 302, wherein transmission photons enter the first faraday mirror 303 retrodeviate
Vibration is rotated by 90 ° to be returned by original optical path, and reflection photon is visited through the first optoisolator 304 into the first single-photon detector 305
It surveys, it is synchronous for clock.
The clock synchronization unit Bob4 ' includes the 4th narrow band filter 401, the second beam splitter 402, the second faraday mirror
403, the second optoisolator 404 and the second single-photon detector 405；4th narrow band filter 401, which receives, comes from transmission unit 2 '
Idler photon, filter stray light after enter the second beam splitter 402, wherein transmission photons enter the second faraday mirror 403 retrodeviate
Vibration is rotated by 90 ° to be returned by original optical path, and reflection photon is visited through the second optoisolator 404 into the second single-photon detector 405
It surveys, it is synchronous for clock.
The measuring unit 5 ' includes the 5th narrow band filter 501, the 6th narrow band filter 502, the first Polarization Controller
503, the second Polarization Controller 504, third beam splitter 505, third single-photon detector the 506, the 4th but 507 He of photon detector
Coincidence counting device 508；5th narrow band filter 501 receives the signal photon from transmission unit, enters the after filtering stray light
One Polarization Controller 503 enters third beam splitter 505 after adjusting polarization；6th narrow band filter 502, which receives, comes from transmission unit
Idler photon, filter stray light after enter the second Polarization Controller 504, adjust polarization after enter third beam splitter 505；Signal
HOM interference occurs at third beam splitter 505 for photon and idler photon, passes through third single-photon detector 506 and the 4th monochromatic light
Sub- detector 507 records event, and the size of HOM interference effect is calculated by coincidence counting device 508.
As shown in figure 8, a kind of clock synchronizing method based on quantum entanglement, the above-mentioned one kind of this method is based on quantum entanglement
Clock system, comprising the following steps:
S1, system initialization: inspection tangle source unit, transmission unit, measuring unit and clock synchronization unit Alice and
The hardware facility of Bob, checks whether equipment runs well, and sets primary condition；
S2, optical path coarse adjustment: the length of fibre delay line, the distance of guarantee clock synchronization unit to measuring unit are manually adjusted
It is rough equal；
S3, optical path fine tuning: electrically controllable optical delay line time delay is arranged in transmission unit, and measuring unit passes through measurement entangled photon pairs
Interference obtain photon count value；
S4, it finds HOM effect maximum value: repeating S3 more times, Step wise approximation HOM interference curve maximum value；
S5, after S4 obtains maximum value, Alice and Bob calibrate local clock by respective single-photon detector；
S6, timing repeat S3~S5, realize the real-time synchronization of clock.
When the invention works, the pump laser 101 issues the pulse laser near 790nm, is incident on non-linear crystalline substance
Body (nonlinear crystal uses PPKTP crystal) generates the signal photon and idler photon pair of frequency entanglement.It is managed according to quantum optices
By the two-photon state generated in conversion process under Spontaneous Parametric indicates are as follows:
WhereinWithThe respectively creation operator of signal light and ideler frequency light, | 0 > is vacuum state, A (ωs,
ωi)=α (ωs,ωi)ΦL(ωs,ωi) be two-photon joint spectrum amplitude, by the spectrum shape function α (ω of pumping lights,ωi)
With the phase matched function phi of parametric down conversion processL(ωs,ωi) determine.
The synchronization accuracy of system depends on the result of interference of HOM interferometer, and this result of interference depends on frequency entanglement
The spectral property in source is proportional to by interference strength spectrum:
∫∫dωsdωi(|A(ωs,ωi)|2-|A(ωs,ωi)A(ωi,ωs)|cos[(ωs-ωi)τ])
Wherein, A (ωs, ωi) be entangled photon pairs spectral function, τ is the arrival delay of signal light and idle light, passes through reason
Estimate by with existing device performance, reasonably optimizing A (ωs, ωi) synchronization accuracy of system can be improved.
Parametric down conversion process generates entangled photon pairs similar in frequency, and signal photon is sent to clock by transmission unit
Synchronization unit Alice, idler photon are sent to clock synchronization unit Bob by transmission unit.Clock synchronization unit is reflected back survey
Unit is measured, the time data that wherein photon reaches clock synchronization unit Alice and clock synchronization unit Bob are denoted as respectively:
WithArrive separately at clock synchronization unit Alice and the clock synchronization unit Bob time of signal photon and idler photon can be with
Write as function f (t):
The cross-correlation calculated between two functions is deviated with extraction time:
To time integral:
Time migration can be byIt determines, realizes that Alice's and Bob is same by adding compensation rate τ to clock B
Step.
The pump laser 101 selects mode locking ti sapphire laser, is 790nm by central wavelength；The non-linear crystalline substance
Body is the PPKTP crystal of TypeII phase matched, and by rational design periodic structure, frequency phase can be obtained by pumping laser
Close entangled photon pairs.
First narrow band filter and the second narrow band filter are for filtering pump light signals and stray light.
The transmission unit 2 ' is by the first polarization beam apparatus 201, the second polarization beam apparatus 202, electrically controllable optical delay line
203, manual variable optical delay line 204, the first optical fiber link 205 and the second optical fiber link 206 form.First polarization beam apparatus and
Second polarization beam splitting transmission level polarised light, reflects orthogonal polarized light, and the resolution ratio of electrically controllable optical delay line is 1fs.
The clock synchronization unit 3 ' includes third narrow band filter 301, the first beam splitter 302, the first faraday mirror
303, the first optoisolator 304 and the first single-photon detector 305.Narrow band filter is according to signal light-wave progress in the present embodiment
Row selection, the first beam splitter are 50:50 beam splitter, and the optical fiber faraday rotation mirror of single port can be used in the first faraday mirror, the
One single-photon detector is selected as InGaAs near-infrared single photon detector idQuantique id210.
The clock synchronization unit 4 ' includes the 4th narrow band filter 401, the second beam splitter 402, the second faraday mirror
403, the second optoisolator 404 and the second single-photon detector 405.Narrow band filter is according to signal light-wave progress in the present embodiment
Row selection, the second beam splitter are 50:50 fiber optic splitter, and the optical fiber Faraday rotation of single port can be used in the second faraday mirror
Mirror, the second single-photon detector are selected as InGaAs near-infrared single photon detector idQuantique id210.
The measuring unit 5 ' includes the 5th narrow band filter 501, the 6th narrow band filter 502, the first Polarization Controller
503, the second Polarization Controller 504, third beam splitter 505, third single-photon detector the 506, the 4th but photon detection 507 and symbol
Total number device 508.Narrow band filter is selected according to signal light wavelength in the present embodiment, Polarization Controller General
Photonics MPC, beam splitter are 50:50 fiber optic splitter, and single-photon detector is selected as the spy of InGaAs near-infrared single photon
Device idQuantique id210 is surveyed, coincidence counting device is standford SR620.
By the explanation of above-mentioned specific embodiment, it is proposed that it is a kind of based on the clock system tangled and side
Wavelength is laser, the nonlinear crystal, polarization beam apparatus, electrically controllable optical delay line, optical fiber near 790nm by method, the system
Link, faraday mirror, single-photon detector etc. are connected in turn, and pass through electrically controllable optical delay line fine adjustment to be synchronized two
The length of optical path realizes that clock is synchronous so that both sides to be synchronized reach middle position simultaneously with this.Using single polarization state light
Son is simultaneously shaken using the polarization of the automatic compensated optical fiber of faraday mirror, can be improved the visibility of HOM effect, so that it is same to increase the time
The precision of step.
The same or similar label correspond to the same or similar components.
According to the disclosure and teachings of the above specification, those skilled in the art in the invention can also be to above-mentioned embodiment party
Formula is changed and is modified.Therefore, the invention is not limited to the specific embodiments disclosed and described above, to the one of invention
A little modifications and changes should also be as falling into the scope of the claims of the present invention.In addition, although being used in this specification
Some specific terms, these terms are merely for convenience of description, does not constitute any restrictions to invention.
Claims (10)
1. a kind of clock system based on quantum entanglement, it is characterised in that: including tangling source unit, transmission unit, clock
Synchronization unit Alice, clock synchronization unit Bob and measuring unit, in which:
It is described to tangle source unit transmitting signal photon and the two-way entangled photons pulse mutually tangled of idler photon, signal photon and
Idler photon is respectively sent to clock synchronization unit Alice and clock synchronization unit Bob through transmission unit, and same in the clock
Step unit Alice and Bob are reflected, and the pulse after reflection is sent to the measuring unit through transmission unit；
The measuring unit reception is sended over the pulse of two-way entangled photons by the transmission unit and is measured to it；
The transmission unit repeatedly adjusts the delay between two-way entangled photons pulse optical path and obtains HOM by coincidence counting and does
Relate to curve；
The maximum value for obtaining HOM interference curve, at the maximum value moment, two-way entangled photons pulse reaches clock synchronization unit
The time of Alice and Bob is identical, and the clock synchronization unit Alice and Bob carries out time synchronization by single-photon detector；
Signal photon and idler photon arrive separately at clock synchronization unit Alice and the clock synchronization unit Bob time is function f
(t):
Wherein, whereinWithIt indicates signal photon and idler photon arrives separately at clock synchronization unit Alice and clock is same
The time data of unit B ob are walked, N indicates pendulous frequency.
2. the clock system according to claim 1 based on quantum entanglement, it is characterised in that: described to tangle source unit
Including pump laser, nonlinear crystal, the first narrow band filter and the second narrow band filter；
The pump laser generates pumping laser, and pumping laser enters nonlinear crystal and generates signal photon and idler photon
The two-way entangled photons pulse mutually tangled, wherein signal photon is sent to transmission unit after entering the first narrow band filter, not busy
Frequency photon is sent to the transmission unit after entering the second narrow band filter.
3. the clock system according to claim 2 based on quantum entanglement, it is characterised in that: the pump light is arteries and veins
Punching or continuous wave laser；
The pump light Output of laser wavelength is 790nm；
The nonlinear crystal is Type II PPKTP crystal；
When the pump light is pulse laser, detector works under gating patterns；
When the pump light is continuous wave laser, detector is worked in continuous mode.
4. the clock system according to claim 2 based on quantum entanglement, it is characterised in that: the transmission unit packet
Include the first polarization beam apparatus, the second polarization beam apparatus, electrically controllable optical delay line, manual variable optical delay line, the first optical fiber link
With the second optical fiber link；
The transmission unit is received from the signal photon for tangling source unit, into first polarization beam apparatus, partially through first
Shake beam splitter transmission level polarised light, enters back into the electrically controllable optical delay line, when adjusting by the electrically controllable optical delay line
It delays and enters the first optical fiber link, be sent to clock synchronization unit Alice through the first optical fiber link；
The transmission unit is received from the idler photon for tangling source unit, into second polarization beam apparatus, partially through second
Shake beam splitter transmission level polarised light, the manual variable optical delay line is entered back into, by the manual variable optical delay line tune
Enter the second optical fiber link after saving time delay, is sent to clock synchronization unit Bob through the second optical fiber link.
5. the clock system according to claim 4 based on quantum entanglement, it is characterised in that: the electrically controllable light prolongs
Slow line is for accurate control light path；The manual variable optical delay line is for controlling roughly light path.
6. the clock system according to claim 1 based on quantum entanglement, it is characterised in that: the clock synchronizes list
First Alice includes third narrow band filter, the first beam splitter, the first faraday mirror, the first optoisolator and the first single-photon detecting
Survey device；
The clock synchronization unit Alice receives the signal photon from transmission unit, filters through third narrow band filter spuious
Enter the first beam splitter after light, transmitted and reflected at the first beam splitter, wherein transmission photons enter the first faraday mirror
Rear polarizer is rotated by 90 ° to be returned by original optical path；Reflection photon enters the first single-photon detector through the first optoisolator and is visited
It surveys, it is synchronous for clock；
First beam splitter be 50:50 beam splitter, the first faraday mirror use single port optical fiber faraday rotation mirror, first
Single-photon detector is near-infrared single photon detector.
7. the clock system according to claim 1 based on quantum entanglement, it is characterised in that: the clock synchronizes list
First Bob includes the 4th narrow band filter, the second beam splitter, the second faraday mirror, the second optoisolator and the second single photon detection
Device；
The clock synchronization unit Bob receives the idler photon from transmission unit, filters stray light through the 4th narrow band filter
Enter the second beam splitter afterwards, transmitted and reflected at the second beam splitter, after wherein transmission photons enter the second faraday mirror
Polarization is rotated by 90 ° to be returned by original optical path；Reflection photon enters the second single-photon detector through the second optoisolator and is detected,
It is synchronous for clock；
Second beam splitter is 50:50 beam splitter, and the optical fiber faraday rotation mirror of single port can be used in the second faraday mirror, the
Two single-photon detectors are near-infrared single photon detector.
8. the clock system according to claim 6 or 7 based on quantum entanglement, it is characterised in that: the transmission is single
Member is received from the clock synchronization unit Alice and Bob vertical polarization signal photon being reflected back and idler photon, wherein believing
Number photon enters the first polarization beam apparatus, and reflected light is sent to measuring unit by first annular device, and idler photon enters second
Polarization beam apparatus, reflected light are sent to measuring unit by the second circulator.
9. the clock system according to claim 8 based on quantum entanglement, it is characterised in that: the measuring unit packet
Include the 5th narrow band filter, the 6th narrow band filter, the first Polarization Controller, the second Polarization Controller, third beam splitter, third
Single-photon detector, the 4th single-photon detector and coincidence counting device；
After 5th narrow band filter receives the signal photon filtering stray light from the transmission unit, by the first Polarization Control
Device enters third beam splitter after adjusting polarization, and it is miscellaneous that the 6th narrow band filter receives the idler photon filtering from the transmission unit
After astigmatism, enter third beam splitter after the second Polarization Controller adjusts polarization；Signal photon and idler photon are in third point
Beam device generates interference, distinguishes recording and sending to coincidence counting device by third single-photon detector and the 4th single-photon detector.
10. a kind of clock synchronizing method based on quantum entanglement, this method is applied to a kind of any base of claim 1-9
In the clock system of quantum entanglement, it is characterised in that: the following steps are included:
S1, system initialization: source unit, transmission unit, measuring unit and clock synchronization unit Alice and Bob are tangled in inspection
Hardware facility, checks whether equipment runs well, and sets primary condition；
S2, optical path coarse adjustment: manually adjusting the length of fibre delay line, guarantee measuring unit to clock synchronization unit Alice and when
The distance of clock synchronization unit Bob is equal roughly；
S3, optical path fine tuning: electrically controllable optical delay line time delay is arranged in transmission unit, and measuring unit is dry by measurement entangled photon pairs
It relates to obtain photon count value；
S4, it finds HOM effect maximum value: repeating S3 more times, Step wise approximation HOM interference curve maximum value；
S5, after S4 obtains maximum value, Alice and Bob calibrate local clock by respective single-photon detector；
S6, timing repeat S3~S5, realize the real-time synchronization of clock.
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| PCT/CN2019/129494 WO2020140850A1 (en) | 2018-12-30 | 2019-12-27 | Clock synchronization system based on quantum entanglement, and method |
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| WO2020140850A1 (en) * | 2018-12-30 | 2020-07-09 | 华南师范大学 | Clock synchronization system based on quantum entanglement, and method |
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