Single photon source anti-bunching measurement apparatus and method

Abstract

The application discloses a single-photon source anti-bunching measurement device and method, relates to the technical field of single-photon detection, and comprises a single-photon source module, a signal trigger light path module, an interference light path module, a single-photon detector module and a coincidence counting module. The single-photon detector module comprises a first gated single-photon detector, a second gated single-photon detector, a first single-photon detector and a second single-photon detector, and can realize accurate measurement of the anti-bunching value of a deterministic single-photon source and a heralded single-photon source.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of single photon detection, and in particular to a single photon source anti-bunching measurement device and method. BACKGROUND

[0002] A single photon source is a new type of quantum light source, which has the ability to emit single photons. This characteristic makes it a core device for quantum communication, quantum radar, quantum imaging and other equipment.

[0003] Single photon sources are divided into deterministic single photon sources and heralded single photon sources. Deterministic single photon sources can emit single photons to some extent according to the user's needs. Such single photon sources are "deterministic", such as single photon sources based on molecules, atoms, diamond nanometer color centers, quantum dots, etc. Deterministic single photon sources have important applications in the fields of quantum communication and quantum computing. A heralded single photon source uses nonlinear optical materials to generate entangled photon pairs. Since entangled photon pairs are generated in pairs, by monitoring one photon, it can be predicted whether the corresponding single photon is generated. A heralded single photon source usually uses spontaneous four-wave mixing and spontaneous parametric down-conversion processes to generate it. Its experimental preparation system is simple and the method is mature, and it has wide application in advanced equipment such as quantum communication, quantum radar, and quantum imaging.

[0004] The anti-bunching value is a core parameter for measuring the performance of a single photon source, which represents the single photon property of the single photon source. Precise measurement of the anti-bunching value of a single photon source plays an important role in the development and performance evaluation of the single photon source. At the same time, it also plays a key role in ensuring the performance indicators of equipment such as quantum communication, quantum radar, and quantum imaging that use single photon sources as light sources. In related technical solutions for measuring the anti-bunching of a single photon source, the following problems exist: The anti-bunching value of a deterministic single photon source can usually be measured, but the anti-bunching value of a heralded single photon source cannot be measured; The wavelength of a single photon source is generally around 1550nm, but the anti-bunching value of a single photon source with a wavelength of 950-1530nm or 1565-1650nm cannot be measured; Synchronous triggering measurement is usually performed using a field programmable gate array (FPGA) and an optical switch, resulting in a complex measurement control system; The influence of stray light, single photon detector dark count, and post-pulse on double and triple random coincidence counting cannot be effectively eliminated through hardware means, resulting in inaccurate measurement accuracy. SUMMARY

[0005] The purpose of the present application is to provide a single photon source anti-bunching measurement device that can accurately measure the anti-bunching value of deterministic single photon sources and heralded single photon sources.

[0006] In a first aspect, the present application provides a single photon source anti-bunching measurement device, the device comprising a single photon source module, a signal trigger light path module, an interference light path module, a single photon detector module, and a coincidence counting module, the single photon detector module comprising a first gated single photon detector, a second gated single photon detector, a first single photon detector, and a second single photon detector, wherein

[0007] The single photon source module is capable of generating deterministic single photons or heralded single photons of different wavelengths;

[0008] For deterministic single photons of any wavelength, the interference light path module outputs the deterministic single photons of the wavelength through the corresponding light path to the first single photon detector and the second single photon detector, respectively, the first single photon detector and the second single photon detector perform photon counting on the respective received deterministic single photons to obtain photon counting results, the coincidence counting module performs coincidence counting on the photon counting results to obtain first coincidence photon counting results, the photon counting results and the first coincidence photon counting results are corrected using the dark counts of the first single photon detector and the second single photon detector and random coincidence photon counts, and the anti-bunching value of the deterministic single photon source is calculated based on the corrected photon counting results and the first coincidence photon counting results;

[0009] For heralded single photon signals of any wavelength, the signal photons in the heralded single photon signals enter the signal trigger light path module and are output to the first gated single photon detector / second gated single photon detector through the corresponding light path of the wavelength, the first gated single photon detector / second gated single photon detector performs photon counting on the received signal photons to obtain signal photon counting results; the idler photons in the heralded single photon signals enter the interference light path module and are output to the first single photon detector and the second single photon detector through the corresponding light path of the wavelength, respectively, the first single photon detector and the second single photon detector perform photon counting on the respective received idler photons to obtain idler photon counting results, the coincidence counting module performs coincidence counting on the signal photon counting results and the idler photon counting results to obtain second coincidence photon counting results, the signal photon counting results and the second coincidence photon counting results are corrected using the dark counts of the first gated single photon detector / second gated single photon detector, the first single photon detector, and the second single photon detector and random coincidence photon counts, and the anti-bunching value of the heralded single photon source is calculated based on the corrected signal photon counting results and the second coincidence photon counting results.

[0010] Optionally, the signal trigger light path module comprises a visible light fiber light path, a near-infrared light fiber light path, a first coupling filter light path, and a second coupling filter light path, wherein,

[0011] The fiber input end of the visible light fiber optical path is connected with the single photon source module through a fiber jumper, the fiber output end is connected with the first gated single photon detector through a fiber jumper, and the visible light fiber optical path is used for coupling and filtering signal photons into signal photons of visible light wavelength and outputting to the first gated single photon detector;

[0012] The fiber input end of the near-infrared light fiber optical path is connected with the single photon source module through a fiber jumper, the fiber output end is connected with the second gated single photon detector through a fiber jumper, and the near-infrared light fiber optical path is used for coupling and filtering signal photons into signal photons of near-infrared light wavelength and outputting to the second gated single photon detector;

[0013] The spatial light input end of the first coupling and filtering optical path is connected with the single photon source module through a fiber jumper, the fiber output end is connected with the first gated single photon detector through a fiber jumper, and the first coupling and filtering optical path is used for coupling and filtering signal photons of spatial light signals into signal photons of fiber light signals in the wavelength range of 650-1050 nm and outputting to the first gated single photon detector;

[0014] The spatial light input end of the second coupling and filtering optical path is connected with the single photon source module through a fiber jumper, the fiber output end is connected with the second gated single photon detector through a fiber jumper, and the second coupling and filtering optical path is used for coupling and filtering signal photons of spatial light signals into signal photons of fiber light signals in the wavelength range of 1050-1650 nm and outputting to the second gated single photon detector.

[0015] Optionally, the interference optical path module comprises a coupling and filtering unit and a polarization splitting unit, the coupling and filtering unit has one spatial light input end and two fiber output ends, and the polarization splitting unit has six fiber input ends and six pairs of fiber output ends, wherein,

[0016] The coupling and filtering unit comprises a third coupling and filtering optical path and a fourth coupling and filtering optical path;

[0017] The polarization splitting unit comprises six polarization splitting branches, each polarization splitting branch comprises a bias controller, a beam splitter and a time delay module, the six polarization splitting branches are a first polarization splitting branch, a second polarization splitting branch, a third polarization splitting branch, a fourth polarization splitting branch, a fifth polarization splitting branch and a sixth polarization splitting branch, the third coupling and filtering optical path / the fourth coupling and filtering optical path is connected with any one of the six polarization splitting branches through a fiber jumper, and any one of the six polarization splitting branches is connected with the first single photon detector / the second single photon detector through a fiber jumper;

[0018] The third coupling filtering light path couples and filters the deterministic single photon / idler photon of the spatial optical signal into the deterministic single photon / idler photon of the fiber optical signal in the wavelength range of 950-1050 nm, and inputs the deterministic single photon / idler photon into a polarization splitting branch corresponding to the wavelength of the deterministic single photon / signal photon. In the polarization splitting branch, a bias controller adjusts the polarization state of the deterministic single photon / idler photon, and a beam splitter divides the deterministic single photon / idler photon after adjusting the bias state into two paths at a ratio of 50 / 50, outputs one path of the deterministic single photon / idler photon to the first single photon detector, and outputs the other path of the deterministic single photon / idler photon to the second single photon detector after time adjustment by a time delay module, so that the two paths of the deterministic single photon / idler photon reach the first single photon detector and the second single photon detector at the same time.

[0019] The fourth coupling filtering light path couples and filters the deterministic single photon / idler photon of the spatial optical signal into the deterministic single photon / idler photon of the fiber optical signal in the wavelength range of 1050-1650 nm, and inputs the deterministic single photon / idler photon into a polarization splitting branch corresponding to the wavelength of the deterministic single photon / signal photon. In the polarization splitting branch, a bias controller adjusts the polarization state of the deterministic single photon / idler photon, and a beam splitter divides the deterministic single photon / idler photon after adjusting the bias state into two paths at a ratio of 50 / 50, outputs one path of the deterministic single photon / idler photon to the first single photon detector, and outputs the other path of the deterministic single photon / idler photon to the second single photon detector after time adjustment by a time delay module, so that the two paths of the deterministic single photon / idler photon reach the first single photon detector and the second single photon detector at the same time.

[0020] Optionally, the interference light path module outputs the deterministic single photons to the first single photon detector and the second single photon detector, respectively.

[0021] The first single photon detector and the second single photon detector perform photon counting on the respective received deterministic single photons to obtain a first photon count N T and a second photon count N R .

[0022] The coincidence counting module performs coincidence counting on the first photon count and the second photon count to obtain a first coincidence photon count N TR .

[0023] In the case of no light input, a first dark count N T dark of the first single photon detector and a second dark count N R dark of the second single photon detector are obtained, and a random coincidence photon count NTR dark,total , random coincidence photon counts N between the dark counts of the second single photon detector and the total photon counts of the first single photon detector TR total,dark , random coincidence photon counts N between the dark counts of the first single photon detector and the dark counts of the second single photon detector TR dark,dark ;

[0024] According to N T dark , N R dark , N TR dark,total , N TR total,dark , N TR dark,dark , the first photon counts N T , the second photon counts N R and the first coincidence photon counts N TR are respectively corrected to obtain the first real photon counts N T true , the second real photon counts N R true and the first real coincidence photon counts N TR true ;

[0025] According to the first real photon counts N T true , the second real photon counts N R true and the first real coincidence photon counts N TR true , the de-bunching value of the deterministic single photon source is calculated.

[0026] Optionally, the first real photon counts N T true , the second real photon counts N R true and the first real coincidence photon counts N TR true are calculated according to the following formula:

[0027] N T true =N T -N T dark ;

[0028] N R true =N R -N Rdark ;

[0029] N TR true =N TR -N TR dark,total -N TR total,dark +N TR dark,dark ;

[0030] The anti-bunching value of the deterministic single photon source is calculated according to the following formula true :

[0031] ;

[0032] Wherein, K1 represents a correction factor, ΔT represents a total counting time, and Δt represents a coincidence counting time gate width.

[0033] Optionally, the coincidence counting module comprises a time delay device and a time-correlated photon counting unit, the time delay device is electrically connected with the first single photon detector and the second single photon detector, wherein,

[0034] The time delay device adjusts a trigger time delay of the first single photon detector and the second single photon detector, so that the trigger time delay is 0, and the time-correlated photon counting unit is used to perform coincidence counting.

[0035] Under the condition that the trigger time delay is 0, the first photon count N T , the second photon count N R and the first coincidence photon count N TR are recorded by measurement.

[0036] Under the condition that the trigger time delay is 0 and the first single photon detector has no light input, the first dark count N T dark is recorded by measurement.

[0037] Under the condition that the trigger time delay is 0 and the second single photon detector has no light input, the second dark count N R dark is recorded by measurement.

[0038] Under the condition that the trigger time delay is 0, the first single photon detector has no light input, and the second single photon detector has light input, the random coincidence photon count N TR dark,total between the dark count of the first single photon detector and the total photon count of the second single photon detector is recorded by measurement.

[0039] Under the condition that the trigger time delay is 0, the first single photon detector has light input and the second single photon detector has no light input, the random coincidence photon count N between the total photon count of the first single photon detector and the dark count of the second single photon detector is measured and recorded TR total,dark ;

[0040] Under the condition that the trigger time delay is 0, the first single photon detector and the second single photon detector have no light input, the random coincidence photon count N between the dark count of the first single photon detector and the dark count of the second single photon detector is measured and recorded TR dark,dark .

[0041] Optionally, the first / second gated single photon detector pair performs photon counting on the received signal photons to obtain a signal photon count N G total The first / second gated single photon detector is identified as a gated single photon detector;

[0042] The first single photon detector and the second single photon detector perform photon detection on the respective received idler photons;

[0043] The coincidence counting module performs coincidence counting on the signal photon count N G total and the idler photons detected by the first single photon detector to obtain a second coincidence photon count N GT total,total , the signal photon count N G total and the idler photons detected by the second single photon detector to obtain a third coincidence photon count N GR total,total , and the signal photon N G total , the idler photons detected by the first single photon detector and the idler photons detected by the second single photon detector to obtain a triple coincidence photon count N GTR total,total,total ;

[0044] In the case of no light input, wherein,

[0045] A third dark count N of the gated single photon detector is obtained G dark ;

[0046] A random coincidence photon count N between the dark count of the gated single photon detector and the total photon count of the first single photon detector is obtained GT dark,total, the random coincidence photon count N between the total photon count of the gated single photon detector and the dark count of the first single photon detector GT total,dark , the random coincidence photon count N between the dark count of the gated single photon detector and the dark count of the first single photon detector GT dark,dark ;

[0047] , the random coincidence photon count N between the total photon count of the gated single photon detector and the dark count of the second single photon detector GR dark,total , the random coincidence photon count N between the total photon count of the gated single photon detector and the dark count of the second single photon detector GR total,dark , the random coincidence photon count N between the dark count of the gated single photon detector and the dark count of the second single photon detector GR dark,dark ;

[0048] , the random coincidence photon count N between the total photon count of the gated single photon detector, the total photon count of the first single photon detector and the dark count of the second single photon detector GTR total,total,dark , the random coincidence photon count N between the total photon count of the gated single photon detector, the dark count of the first single photon detector and the total photon count of the second single photon detector GTR total,dark,total , the random coincidence photon count N between the total photon count of the gated single photon detector, the dark count of the first single photon detector and the dark count of the second single photon detector GTR total,dark,dark , the random coincidence photon count N between the dark count of the gated single photon detector, the total photon count of the first single photon detector and the total photon count of the second single photon detector GTR dark,total,total , the random coincidence photon count N between the dark count of the gated single photon detector, the total photon count of the first single photon detector and the dark count of the second single photon detector GTR dark ,total,dark , the random coincidence photon count N between the dark count of the gated single photon detector, the dark count of the first single photon detector and the total photon count of the second single photon detector GTR dark, dark,total , the random coincidence photon count N between the dark count of the gated single photon detector, the dark count of the first single photon detector and the dark count of the second single photon detector GTR dark,dark,dark ;

[0049] from NG dark N G total N G true N GT dark,total N GT total N ,dark GT N dark,dark GT N total,total N GT true N GR dark,total N GR total,dark N GR dark,dark N GR total,total N GR true N GTR total,total,dark N GTR total,dark,total N GTR total, dark,dark N GTR dark,total,total N GTR dark,total,dark N GTR dark,dark,total N GTR dark,dark,dark N GTR total,total,total N GTR true

[0050] N G true N GT true N GR true N GTR true

[0051] N G true N GT true ​, third true coincidence photon count N GR true and true triple coincidence photon count N GTR true ;

[0052] N G true = N G total - N G dark ;

[0053] N GT true = N GT total,total - N GT dark,total - N GT total, dark + N GT dark, dark ;

[0054] N GR true = N GR total,total - N GR dark,total - N GR total,dark + N GR dark,dark ;

[0055] N GTR true = N GTR total,total,total - N GTR total,total,dark - N GTR total,dark,total - N GTR total,dark,dark - N GTR dark,total,total - N GTR dark,total,dark - N GTR dark, dark,total + 5N GTR dark, dark,dark ;

[0056] The anti-bunching value a2 of the heralded single-photon source is calculated according to the following formula true :

[0057] ;

[0058] wherein K2 represents a correction factor.

[0059] Optionally, the coincidence counting module comprises a time delay device and a time-correlated photon counting unit, the time delay device is electrically connected with the first single-photon detector and the second single-photon detector, wherein,

[0060] The time delay device adjusts the trigger time delay of the first single-photon detector and the second single-photon detector to 0;

[0061] Under the condition that the trigger time delay is 0, the synchronous measurement record obtains the signal photon count N G total detected by the first gated single-photon detector / second gated single-photon detector G total and the idler photons detected by the first single-photon detector and the second single-photon detector, and the time-correlated photon counting unit performs coincidence counting on the signal photon count N GR total,total and the idler photons detected by the first single-photon detector and the second single-photon detector, to obtain the third coincidence photon count N G total and the idler photons detected by the first single-photon detector and the second single-photon detector, to obtain the triple coincidence photon count N GTR total,total,total .

[0062] In a second aspect, the present application provides a single-photon source anti-bunching measurement method, the method comprising:

[0063] acquiring deterministic single photons or heralded single photons of different wavelengths;

[0064] For any wavelength of deterministic single photon, the deterministic single photon is output to the first single-photon detector and the second single-photon detector through the optical path corresponding to the wavelength, the first single-photon detector and the second single-photon detector perform photon counting on the respective received deterministic single photons to obtain photon counting results, coincidence counting is performed on the photon counting results to obtain first coincidence photon counting results, the photon counting results and the first coincidence photon counting results are corrected using the dark counts of the first single-photon detector and the second single-photon detector and random coincidence photon counts, and the anti-bunching value of the deterministic single-photon source is calculated based on the corrected photon counting results and the first coincidence photon counting results;

[0065] For any wavelength of heralded single photon signal, the signal photon in the heralded single photon signal enters the optical path corresponding to the wavelength and is output to the first gated single photon detector / second gated single photon detector, and the first gated single photon detector / second gated single photon detector performs photon counting on the received signal photon to obtain a signal photon counting result; the idler photon in the heralded single photon signal enters an interference optical path module and is output to the first single photon detector and the second single photon detector through the optical path corresponding to the wavelength, respectively, and the first single photon detector and the second single photon detector perform photon counting on the received idler photon to obtain an idler photon counting result, coincidence counting is performed on the signal photon counting result and the idler photon counting result to obtain a second coincidence photon counting result, the signal photon counting result and the second coincidence photon counting result are corrected by using the dark count of the first gated single photon detector / second gated single photon detector, the first single photon detector and the second single photon detector, and random coincidence photon counting, and the anti-bunching value of the heralded single photon source is calculated based on the corrected signal photon counting result and the second coincidence photon counting result.

[0066] The present application can simultaneously realize the anti-bunching value measurement of the deterministic single photon source and the heralded single photon source, and can realize the anti-bunching value measurement of the single photon source with a wavelength in the range of 950-1650 nm. By adopting a wide-band full-fiber optical path scheme, the background stray light is effectively suppressed, and the measurement accuracy of the photon counting is improved. By correcting the photon counting and the coincidence photon counting, the calibration error of the anti-bunching value measurement of the deterministic single photon source and the heralded single photon source is compensated, the accurate measurement of the anti-bunching value is realized, and the measurement accuracy of the anti-bunching value is improved. The present application directly adopts the gated single photon detector to realize the synchronous trigger measurement, without adopting the FPGA and the optical switch, thereby reducing the complexity and cost of the synchronous measurement. The present application is suitable for the single photon source with spatial light output and the single photon source with fiber output. BRIEF DESCRIPTION OF DRAWINGS

[0067] Figure 1 The first system block diagram of the single photon source anti-bunching measurement device provided by the embodiment of the present application;

[0068] Figure 2 The second system block diagram of the single photon source anti-bunching measurement device provided by the embodiment of the present application;

[0069] Figure 3 The comparative curve diagram of the anti-bunching value of the heralded single photon source provided by the embodiment of the present application. DETAILED DESCRIPTION

[0070] The application will be described in detail below with reference to the specific embodiments shown in the drawings, but these embodiments do not limit the application, and the structural, method, or functional changes made by those of ordinary skill in the art based on these embodiments are included in the protection scope of the application.

[0071] Please refer to Figure 1 The embodiment of the application provides a kind of single photon source anti-bunching measurement device, the device includes single photon source module 11, signal trigger light path module 12, interference light path module 13, single photon detector module 14 and coincidence counting module 15.Single photon detector module 14 includes first gated single photon detector 141, second gated single photon detector 142, first single photon detector 143 and second single photon detector 144.Single photon source module 11 can generate single photon of different wavelengths, and single photon includes deterministic single photon or heralded single photon.Heralded single photon includes signal photon and idle frequency photon.Single photon detector is used to convert input single photon signal into identifiable electrical signal output, to achieve the purpose of single photon detection and counting.

[0072] For deterministic single photon of any wavelength, interference light path module 13 outputs deterministic single photon to first single photon detector 143 and second single photon detector 144 through the light path corresponding to the wavelength, and first single photon detector 143 and second single photon detector 144 perform photon counting on the deterministic single photon received by each to obtain photon counting result.Coincidence counting module 15 performs coincidence counting on photon counting result to obtain first coincidence photon counting result, and modifies photon counting result and first coincidence photon counting result using dark count of first single photon detector 143 and second single photon detector 144 and random coincidence photon counting, and calculates anti-bunching value of deterministic single photon source based on modified photon counting result and first coincidence photon counting result, to realize the determination of anti-bunching of deterministic single photon source.

[0073] For any wavelength of heralded single photon signal, the signal photon in the heralded single photon signal enters the signal trigger light path module 12, and is output to the first gated single photon detector 141 / second gated single photon detector 142 through the light path corresponding to the wavelength. The first gated single photon detector 141 / second gated single photon detector 142 performs photon counting on the received signal photon to obtain a signal photon counting result. The idler photon in the heralded single photon signal enters the interference light path module 13, and is respectively output to the first single photon detector 143 and the second single photon detector 144 through the light path corresponding to the wavelength. The first single photon detector 143 and the second single photon detector 144 perform photon counting on the idler photons received by each of them to obtain idler photon counting results. The coincidence counting module 15 performs coincidence counting on the signal photon counting result and the idler photon counting result to obtain a second coincidence photon counting result. The dark count of the first gated single photon detector 141 / second gated single photon detector 142, the first single photon detector 143 and the second single photon detector 144 and the random coincidence photon counting are used to correct the signal photon counting result and the second coincidence photon counting result, and the de-bunching value of the heralded single photon source is calculated based on the corrected signal photon counting result and the second coincidence photon counting result, so as to realize the determination of the de-bunching of the heralded single photon source. The signal photon output by the signal trigger light path module 12 triggers the first gated single photon detector 141 / second gated single photon detector 142 to generate a corresponding electrical pulse signal, so as to realize the photon counting of the signal photon. The first gated single photon detector 141 or the second gated single photon detector 142 is selected based on the wavelength of the signal photon.

[0074] In the embodiment of the present application, the de-bunching value measurement of the deterministic single photon source and the heralded single photon source can be realized at the same time, and the de-bunching value measurement of the single photon source with a wavelength in the range of 950-1650nm can be realized. By using the all-fiber light path scheme with a wide wavelength range, the background stray light is effectively suppressed, and the measurement accuracy of the photon counting is improved. By correcting the photon counting and the coincidence photon counting, the calibration error of the de-bunching value measurement of the deterministic single photon source and the heralded single photon source is compensated, the accurate measurement of the de-bunching value is realized, and the measurement accuracy of the de-bunching value is improved. In the embodiment, the gated single photon detector is directly used to realize the synchronous trigger measurement, and the FPGA and the optical switch are not needed, so that the complexity and cost of the synchronous measurement are reduced. The embodiment is suitable for both the spatial light output single photon source and the fiber output single photon source.

[0075] As shown in the embodiment of the present application, Figure 2 The signal trigger light path module 12 includes a visible light fiber light path 121, a near-infrared light fiber light path 122, a first coupled filter light path 123 and a second coupled filter light path 124.

[0076] The fiber input end of the visible light fiber optical path 121 is connected with the single photon source module 11 through a fiber jumper, and the fiber output end is connected with the first gated single photon detector 141 through a fiber jumper. The visible light fiber optical path 121 is used for coupling and filtering signal photons into signal photons of visible light wavelength and outputting to the first gated single photon detector 141. Exemplarily, the first gated single photon detector 141 is a silicon-based gated single photon detector, and the waveband range suitable for detection of the silicon-based gated single photon detector is 400-1000 nm, so for signal photons of the visible light waveband, the corresponding optical path is the first gated single photon detector 141.

[0077] The fiber input end of the near-infrared light fiber optical path 122 is connected with the single photon source module 11 through a fiber jumper, and the fiber output end is connected with the second gated single photon detector 142 through a fiber jumper. The near-infrared light fiber optical path 122 is used for coupling and filtering signal photons into signal photons of near-infrared light wavelength and outputting to the second gated single photon detector 142. Exemplarily, the second gated single photon detector 142 is an indium gallium arsenide-based gated single photon detector, and the waveband range suitable for detection of the indium gallium arsenide-based gated single photon detector is 1000-1650 nm, so for signal photons of the near-infrared light waveband, the corresponding optical path is the second gated single photon detector 142.

[0078] The spatial light input end of the first coupling and filtering optical path 123 is connected with the single photon source module 11 through a fiber jumper, and the fiber output end is connected with the first gated single photon detector 141 through a fiber jumper. The first coupling and filtering optical path 123 couples and filters signal photons of a spatial light signal into signal photons of a fiber light signal in a waveband range of 650-1050 nm and outputs to the first gated single photon detector 141.

[0079] The spatial light input end of the second coupling and filtering optical path 124 is connected with the single photon source module 11 through a fiber jumper, and the fiber output end is connected with the second gated single photon detector 142 through a fiber jumper. The second coupling and filtering optical path 124 couples and filters signal photons of a spatial light signal into signal photons of a fiber light signal in a waveband range of 1050-1650 nm and outputs to the second gated single photon detector 142.

[0080] Since the background stray light affects the photon counting and coincidence counting of the single photon detector, and further affects the measurement and calibration of the anti-bunching value, the embodiment adopts a fiber optical path module scheme to suppress the influence of the background stray light. The embodiment realizes a wide waveband all-fiber optical path structure through the visible light fiber optical path 121, the near-infrared light fiber optical path 122, the first coupling and filtering optical path 123 and the second coupling and filtering optical path 124, provides mutually independent and non-interfering optical paths for signal photons of each path, and is suitable for both a spatial light output single photon source and a fiber output single photon source.

[0081] One embodiment of the present application, as shown in Figure 3 The interference optical path module 13 includes a coupling filter unit 131 having one spatial light input end and two fiber output ends, and a polarization splitting unit 132 having six fiber input ends and six pairs of fiber output ends. The polarization splitting unit 132 includes six polarization splitting branches, each of which includes a bias controller, a beam splitter, and a time delay module, and each of which has one fiber input end and one pair of fiber output ends. The six polarization splitting branches are a first polarization splitting branch 1321, a second polarization splitting branch 1322, a third polarization splitting branch 1323, a fourth polarization splitting branch 1324, a fifth polarization splitting branch 1325, and a sixth polarization splitting branch 1326. The coupling filter unit 131 includes a third coupling filter optical path 1311 and a fourth coupling filter optical path 1312. The third coupling filter optical path 1311 / fourth coupling filter optical path 1312 is connected to any one of the six polarization splitting branches through a fiber jumper, and any one of the six polarization splitting branches is connected to the first single-photon detector 143 / second single-photon detector 144 through a fiber jumper. The wavelength band of the first polarization splitting branch 1321 is 930±100nm, the wavelength band of the second polarization splitting branch 1322 is 1060±100nm, the wavelength band of the third polarization splitting branch 1323 is 1180±20nm, the wavelength band of the fourth polarization splitting branch 1324 is 1300±100nm, the wavelength band of the fifth polarization splitting branch 1325 is 1430±100nm, and the wavelength band of the sixth polarization splitting branch 1326 is 1550±100nm, thereby realizing single-photon covering a wide wavelength range of 950~1650nm.

[0082] For the deterministic single photon, the single photon source module 11 outputs the deterministic single photon, and the deterministic single photon is input into the interference optical path module 13. Based on the wavelength of the deterministic single photon, a corresponding third coupling filter optical path 1311 or a fourth coupling filter optical path 1312 is selected. If the wavelength is within the wavelength range of 950-1050 nm, the third coupling filter optical path 1311 couples and filters the spatial light signal deterministic single photon into a fiber optical signal deterministic single photon within the wavelength range of 950-1050 nm, and inputs the deterministic single photon into a corresponding polarization splitting branch. The wavelength of each polarization splitting branch can be selected based on the above-mentioned wavelength selection of each polarization splitting branch. In the polarization splitting branch, a bias controller adjusts the polarization state of the deterministic single photon, and a beam splitter divides the deterministic single photon after the polarization state is adjusted into two paths at a ratio of 50 / 50, and outputs one path of the deterministic single photon to the first single photon detector 143, and outputs the other path to the second single photon detector 144 after time adjustment by a time delay module, so that the two paths of the deterministic single photon reach the first single photon detector 143 and the second single photon detector 144 at the same time, thereby realizing detection and counting of the deterministic single photon.

[0083] If the wavelength is within the wavelength range of 1050-1650 nm, the fourth coupling filter optical path 1312 couples and filters the spatial light signal deterministic single photon into a fiber optical signal deterministic single photon within the wavelength range of 1050-1650 nm, and inputs the deterministic single photon into a corresponding polarization splitting branch. In the polarization splitting branch, a bias controller adjusts the polarization state of the deterministic single photon, and a beam splitter divides the deterministic single photon after the polarization state is adjusted into two paths at a ratio of 50 / 50, and outputs one path of the deterministic single photon to the first single photon detector 143, and outputs the other path to the second single photon detector 144 after time adjustment by a time delay module, so that the two paths of the deterministic single photon reach the first single photon detector 143 and the second single photon detector 144 at the same time.

[0084] Exemplarily, the first single photon detector 143 and the second single photon detector 144 are both indium gallium arsenide-based single photon detectors.

[0085] For the heralded single photon, the single photon source module 11 outputs the heralded single photon, and the heralded single photon includes a signal photon and an idler photon. The signal photon is output to the first gated single photon detector 141 / second gated single photon detector 142 through the signal trigger optical path module 12, so as to realize detection and counting of the signal photon by the first gated single photon detector 141 or the second gated single photon detector 142. The idler photon is input into the first single photon detector 143 and the second single photon detector 144 through the interference optical path module 13, so as to realize detection and counting of the idler photon by the first single photon detector 143 and the second single photon detector 144.

[0086] The wavelength of the idler photon is selected to correspond to the third coupling filter optical path 1311 or the fourth coupling filter optical path 1312. If the wavelength is in the wavelength range of 950-1050 nm, the third coupling filter optical path 1311 couples and filters the idler photon of the spatial light signal into an idler photon of the fiber optical signal in the wavelength range of 950-1050 nm, and inputs the idler photon into a corresponding polarization splitting branch. The corresponding polarization splitting branch can be selected based on the wavelength range of each polarization splitting branch. In the polarization splitting branch, the bias controller adjusts the polarization state of the idler photon, and the beam splitter divides the idler photon after the polarization state is adjusted into two paths at a ratio of 50 / 50, and outputs one path of the idler photon to the first single-photon detector 143, and outputs the other path of the idler photon to the second single-photon detector 144 after time adjustment by the time delay module, so that the two paths of the idler photon reach the first single-photon detector 143 and the second single-photon detector 144 at the same time, thereby realizing detection and counting of the idler photon.

[0087] If the wavelength is in the wavelength range of 1050-1650 nm, the fourth coupling filter optical path 1312 couples and filters the idler photon of the spatial light signal into an idler photon of the fiber optical signal in the wavelength range of 1050-1650 nm, and inputs the idler photon into a corresponding polarization splitting branch. In the polarization splitting branch, the bias controller adjusts the polarization state of the idler photon, and the beam splitter divides the idler photon after the polarization state is adjusted into two paths at a ratio of 50 / 50, and outputs one path of the idler photon to the first single-photon detector 143, and outputs the other path of the idler photon to the second single-photon detector 144 after time adjustment by the time delay module, so that the two paths of the idler photon reach the first single-photon detector 143 and the second single-photon detector 144 at the same time, thereby realizing detection and counting of the idler photon.

[0088] In one embodiment of the present application, the interference optical path module 13 outputs the deterministic single photons to the first single-photon detector 143 and the second single-photon detector 144, respectively. The first single-photon detector 143 and the second single-photon detector 144 perform photon counting on the respective received deterministic single photons to obtain the first photon count N T and the second photon count N R . The coincidence counting module 15 performs coincidence counting on the first photon count N T and the second photon count N R to obtain the first coincidence photon count N TR . The coincidence photon count measures the time correlation between different photon events, and belongs to the second-order statistics.

[0089] In the case of no light input, the first dark count N Tdark , the second dark count N of the second single photon detector 144 R dark , and the random coincidence photon count N between the dark count of the first single photon detector 143 and the total photon count of the second single photon detector 144 TR dark,total , the random coincidence photon count N between the total photon count of the first single photon detector 143 and the dark count of the second single photon detector 144 TR total,dark , the random coincidence photon count N between the dark count of the first single photon detector 143 and the dark count of the second single photon detector 144 TR dark,dark According to N T dark , N R dark , N TR dark,total , N TR total,dark , N TR dark,dark , the first photon count N T , the second photon count N R and the first coincidence photon count N TR are corrected respectively to obtain the first real photon count N T true , the second real photon count N R true and the first real coincidence photon count N TR true According to the first real photon count N T true , the second real photon count N R true and the first real coincidence photon count N TR true , the anti-bunching value of the deterministic single photon source is calculated.

[0090] Exemplarily, the first real photon count N T true , the second real photon count N R true and the first real coincidence photon count N TR true are calculated according to the following formula:

[0091] N T true =N T -N T dark ;

[0092] N R true =N R -N R dark ;

[0093] N TR true =N TR -N TR dark,total -N TR total,dark +N TR dark,dark ;

[0094] The anti-bunching value a1 of the deterministic single photon source is calculated according to the following formula true :

[0095] ;

[0096] Wherein, K1 represents a correction factor, AT represents the total counting time, and At represents the coincidence counting time gate width.

[0097] Exemplarily, the coincidence counting module 15 comprises a time delay device 151 and a time-correlated photon counting unit 152. The time delay device 151 is electrically connected with the first single photon detector 143 and the second single photon detector 144. The time delay device 151 adjusts the trigger time delay of the first single photon detector 143 and the second single photon detector 144, so that the trigger time delay is 0. The time-correlated photon counting unit 152 is used to perform coincidence counting, by performing time-correlated statistics on the photon counts output by the first single photon detector 143 and the second single photon detector 144 respectively, to obtain the coincidence photon count. Under the condition that the trigger time delay is 0, the first photon count N T , the second photon count N R and the first coincidence photon count N TR are recorded by measurement. Under the condition that the trigger time delay is 0 and the first single photon detector 143 has no light input, the first dark count N T dark is recorded by measurement. Under the condition that the trigger time delay is 0 and the second single photon detector 144 has no light input, the second dark count N R dark is recorded by measurement. The dark count can be understood as the output pulse event of the single photon detector under the condition of no light. Under the condition that the trigger time delay is 0, the first single photon detector 143 has no light input, and the second single photon detector 144 has light input, the random coincidence photon count N TRdark,total , N TR dark,total represents the false coincidence when the first single photon detector 143 has only dark noise and the second single photon detector 144 has normal photon signals. Under the condition that the trigger time delay is 0, the first single photon detector 143 has light input and the second single photon detector 144 has no light input, the measurement records the random coincidence photon count N TR total,dark , N TR total,dark represents the false coincidence when the second single photon detector 144 has only dark noise and the first single photon detector 143 has normal photon signals. Under the condition that the trigger time delay is 0, the first single photon detector 143 and the second single photon detector 144 have no light input, the measurement records the random coincidence photon count N TR dark,dark , N TR dark,dark represents the coincidence events generated by the respective noises when the first single photon detector 143 and the second single photon detector 144 have no light.

[0098] In the measurement of the anti-bunching value of the deterministic single photon source, the signal measured by the single photon detector contains background noise, dark count and other interference, so in this embodiment, the background and dark count photon counts are eliminated from the total photon count, and various random coincidence counts are eliminated from the coincidence photon count, so that the real photon count and coincidence photon count can be obtained, the real photon count and coincidence photon count are used for calculating the anti-bunching value, and the anti-bunching of the deterministic single photon source can be truly reflected, and the measurement precision of the anti-bunching value is improved.

[0099] In an embodiment of the present application, the first gated single photon detector 141 / second gated single photon detector 142 performs photon counting on the received signal photons to obtain a signal photon count N G total The first gated single photon detector 141 / second gated single photon detector 142 is identified as a gated single photon detector, and the gated single photon detector described below refers to the first gated single photon detector 141 or the second gated single photon detector 142. The first single photon detector 143 and the second single photon detector 144 perform photon detection on the respective received idle frequency photons. The coincidence counting module 15 counts the signal photon count N G total The idle frequency photons detected by the first single photon detector 143 are the second coincidence photon count N GT total,totalCount N signal photons G total The second idler frequency photon count is then used for coincidence counting to obtain the second coincidence photon count N. GT total,total Count N signal photons G total The coincidence count of the idler photons detected by the second single-photon detector 144 is performed to obtain the third coincidence photon count N. GR total,total and the signal photon N G total The idler photons detected by the first single-photon detector 143 and the idler photons detected by the second single-photon detector 144 are coincidentally counted to obtain the triple coincidence photon count N. GTR total ,total,total .

[0100] In the absence of light input, among which,

[0101] Obtain the third dark count N of the gated single-photon detector G dark ;

[0102] Obtain the random coincidence photon count N between the dark count of the gated single-photon detector and the total photon count of the first single-photon detector 143. GT dark,total The random coincidence photon count N between the total photon count of the gated single-photon detector and the dark count of the first single-photon detector 143 GT total,dark The random coincidence photon count N between the dark count of the gated single-photon detector and the dark count of the first single-photon detector 143 GT dark,dark ;

[0103] Obtain the random coincidence photon count N between the dark count of the gated single-photon detector and the total photon count of the second single-photon detector 144. GR dark,total The random coincidence photon count N between the total photon count of the gated single-photon detector and the dark count of the second single-photon detector 144. GR total,dark The random coincidence photon count N between the dark count of the gated single-photon detector and the dark count of the second single-photon detector 144. GR dark,dark ;

[0104] Obtain the random coincidence photon count N between the total photon count of the gated single-photon detector, the total photon count of the first single-photon detector 143, and the dark count of the second single-photon detector 144. GTRtotal,total,dark the random coincidence photon count N between the total photon count of the gated single photon detector, the dark count of the first single photon detector 143, and the total photon count of the second single photon detector 144 GTR total,dark,total the random coincidence photon count N between the total photon count of the gated single photon detector, the dark count of the first single photon detector 143, and the dark count of the second single photon detector 144 GTR total,dark,dark the random coincidence photon count N between the total photon count of the gated single photon detector, the dark count of the first single photon detector 143, and the total photon count of the second single photon detector 144 GTR dark,total,total the random coincidence photon count N between the total photon count of the gated single photon detector, the dark count of the first single photon detector 143, and the dark count of the second single photon detector 144 GTR dark,total,dark the random coincidence photon count N between the total photon count of the gated single photon detector, the dark count of the first single photon detector 143, and the total photon count of the second single photon detector 144 GTR dark, dark,total the random coincidence photon count N between the total photon count of the gated single photon detector, the dark count of the first single photon detector 143, and the dark count of the second single photon detector 144 GTR dark,dark,dark ;

[0105] According to N G dark the third real coincidence photon count N G total is corrected to obtain the second real coincidence photon count N G true According to N GT dark,total , N GT total ,dark and N GT dark,dark the third real coincidence photon count N GT total,total is corrected to obtain the second real coincidence photon count N GT true According to N GR dark,total , N GR total,dark and N GR dark,dark the third real coincidence photon count N GR total,total is corrected to obtain the second real coincidence photon count N GR true According to NGTR total,total,dark , N GTR total,dark,total , N GTR total,dark,dark , N GTR dark,total,total , N GTR dark,total,dark , N GTR dark, dark,total and N GTR dark,dark,dark to N GTR total,total,total corrected to get the true triple coincidence photon count N GTR true ;

[0106] According to the third true photon count N G true , the second true coincidence photon count N GT true , the third true coincidence photon count N GR true and the true triple coincidence photon count N GTR true , the anti-bunching value of the heralded single photon source is calculated.

[0107] Exemplarily, the third true photon count N G true , the second true coincidence photon count N GT true , the third true coincidence photon count N GR true and the true triple coincidence photon count N GTR true are calculated according to the following formula:

[0108] N G true = N G total - N G dark ;

[0109] N GT true = N GT total,total - N GT dark,total - N GT total, dark + N GT dark, dark ;

[0110] N GR true = N GRtotal,total - N GR dark,total - N GR total,dark + N GR dark,dark ;

[0111] N GTR true =N GTR total,total,total - N GTR total,total,dark - N GTR total,dark,total - N GTR total,dark,dark -N GTR dark,total,total - N GTR dark,total,dark -N GTR dark, dark,total +5N GTR dark, dark,dark ;

[0112] The anti-bunching value a2 of the heralded single photon source is calculated according to the following formula true :

[0113] ;

[0114] wherein K2 represents a correction factor.

[0115] Exemplarily, the time delay unit 151 adjusts the trigger time delay of the first single photon detector 143 and the second single photon detector 144, so that the trigger time delay is 0. The time correlation photon counting unit 152 is configured to perform coincidence counting by time-correlation counting the signal photon counts of the first gated single photon detector 141 / second gated single photon detector 142, the idle photon counts of the first single photon detector 143 and the idle photon counts of the second single photon detector 144, to obtain the second coincidence photon counts N GT total,total , the third coincidence photon counts N GR total,total , and the triple coincidence photon counts N GTR total,total,total .

[0116] Under the condition that the trigger time delay is 0, the signal photon counts N G total of the first gated single photon detector 141 / second gated single photon detector 142, the idle photon counts of the first single photon detector 143 and the idle photon counts of the second single photon detector 144 are recorded synchronously, and the time correlation photon counting unit 152 performs time-correlation counting on the signal photon counts NG total and the idler photons detected by the second single photon detector 144 are counted to obtain the third coincidence photon N GR total ,total and the signal photons N G total , the idler photons detected by the first single photon detector 143 and the idler photons detected by the second single photon detector 144 are counted to obtain the triple coincidence photon count N GTR total,total,total The synchronous trigger measurement of the signal photons is realized by using the first gated single photon detector 141 / second gated single photon detector 142, without using FPGAs and optical switches and other devices, thereby reducing the complexity and cost of synchronous measurement.

[0117] Exemplarily, under the condition that the trigger time delay is 0 and the first gated single photon detector 141 / second gated single photon detector 142 has no light input, the third dark count N G dark Under the condition that the trigger time delay is 0, the first gated single photon detector 141 / second gated single photon detector 142 has no light input, and the first single photon detector 143 has light input, the random coincidence photon count N GT dark,total Under the condition that the trigger time delay is 0, the first gated single photon detector 141 / second gated single photon detector 142 has light input, and the first single photon detector 143 has no light input, the random coincidence photon count N GT total,dark Under the condition that the trigger time delay is 0, the first gated single photon detector 141 / second gated single photon detector 142 has no light input, and the first single photon detector 143 has no light input, the random coincidence photon count N GT dark,dark .

[0118] Based on the same implementation as described above, N GR dark,total , N GR total,dark , N GR dark,dark , NGTR total ,total,dark , N GTR total,dark,total , N GTR total, dark,dark , N GTR dark,total,total , N GTR dark,total,dark , N GTR dark , dark,total and N GTR dark, dark,dark , thereby correcting the coincidence photon counts based on obtaining the respective random coincidence photon counts to obtain the true coincidence photon counts.

[0119] In the measurement of the anti-bunching value of the heralded single photon source, the signal measured by the single photon detector contains background noise, dark counts and other interference, therefore, in the embodiment, the background and dark count photon counts are eliminated from the total photon counts, and various random coincidence counts are eliminated from the coincidence photon counts, so that the true photon counts and coincidence photon counts can be obtained, the anti-bunching value is calculated using the true photon counts and true coincidence photon counts, the anti-bunching of the heralded single photon source can be truly reflected, and the measurement precision of the anti-bunching value is improved. As shown in the comparative curve diagram of the anti-bunching value of the heralded single photon source, the red line of the anti-bunching value curve represents that the influence factors of the dark counts and random coincidence counts are not removed in the calculation of the anti-bunching value, and the blue anti-bunching value curve represents that the influence factors of the dark counts and random coincidence counts are removed according to the technical solution of the present application, it can be seen that the anti-bunching value curve based on the technical solution of the present application is more accurate. Figure 3

[0120] The present application provides a single photon source anti-bunching measurement method, the method comprising:

[0121] acquiring deterministic single photons or heralded single photons of different wavelengths;

[0122] For any wavelength of deterministic single photon, the deterministic single photon is output to the first single photon detector 143 and the second single photon detector 144 through the optical path corresponding to the wavelength, the first single photon detector 143 and the second single photon detector 144 perform photon counting on the respective received deterministic single photons to obtain photon counting results, coincidence counting is performed on the photon counting results to obtain first coincidence photon counting results, the dark counts of the first single photon detector 143 and the second single photon detector 144 and the random coincidence photon counts are used to correct the photon counting results and the first coincidence photon counting results, and the anti-bunching value of the deterministic single photon source is calculated based on the corrected photon counting results and the first coincidence photon counting results;

[0123] ​For any wavelength of heralded single photon signal, the signal photons in the heralded single photon signal enter the optical path corresponding to the wavelength and are output to the first gated single photon detector 141 / second gated single photon detector 142, and the first gated single photon detector 141 / second gated single photon detector 142 performs photon counting on the received signal photons to obtain a signal photon counting result; the idler photons in the heralded single photon signal enter the interference optical path module 13 and are respectively output to the first single photon detector 143 and the second single photon detector 144 through the optical path corresponding to the wavelength, the first single photon detector 143 and the second single photon detector 144 perform photon counting on the received idler photons to obtain idler photon counting results, coincidence counting is performed on the signal photon counting result and the idler photon counting result to obtain a second coincidence photon counting result, the signal photon counting result and the second coincidence photon counting result are corrected by using the dark counts of the first gated single photon detector 141 / second gated single photon detector 142, the first single photon detector 143 and the second single photon detector 144 and random coincidence photon counting, and the anti-bunching value of the heralded single photon source is calculated based on the corrected signal photon counting result and the second coincidence photon counting result.

[0124] Although the preferred embodiments of the present application have been disclosed for exemplary purposes, those skilled in the art will realize that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the present application disclosed by the appended claims.

Claims

1. A single-photon source anti-focusing measurement device, characterized in that, The device includes a single-photon source module, a signal triggering optical path module, an interference optical path module, a single-photon detector module, and a coincidence counting module. The single-photon detector module includes a first gated single-photon detector, a second gated single-photon detector, and a first single-photon detector and a second single-photon detector. The single-photon source module can generate deterministic single photons or predictive single photons of different wavelengths; For a deterministic single photon of any wavelength, the interference optical path module outputs the deterministic single photon to the first single-photon detector and the second single-photon detector respectively through the optical path corresponding to that wavelength. The first single-photon detector and the second single-photon detector perform photon counting on the deterministic single photon they receive to obtain a photon counting result. The coincidence counting module performs coincidence counting on the photon counting result to obtain a first coincidence photon counting result. The photon counting result and the first coincidence photon counting result are corrected using the dark count and random coincidence photon count of the first single-photon detector and the second single-photon detector. Based on the corrected photon counting result and the first coincidence photon counting result, the anti-focusing value of the deterministic single-photon source is calculated. For any wavelength of predictive single-photon signal, the signal photon in the predictive single-photon signal enters the signal trigger optical path module and is output to the first gated single-photon detector / second gated single-photon detector through the optical path corresponding to that wavelength. The first gated single-photon detector / second gated single-photon detector counts the received signal photons to obtain the signal photon count result. The idler photon in the predictive single-photon signal enters the interference optical path module and is output to the first single-photon detector and second single-photon detector respectively through the optical path corresponding to that wavelength. The photon detectors count the idler photons they receive to obtain an idler photon count result. The coincidence counting module performs a coincidence count on the signal photon count result and the idler photon count result to obtain a second coincidence photon count result. The signal photon count result and the second coincidence photon count result are corrected using the dark counts of the first gated single-photon detector / second gated single-photon detector, the first single-photon detector and the second single-photon detector, and the random coincidence photon count. Based on the corrected signal photon count result and the second coincidence photon count result, the anti-focusing value of the predictive single-photon source is calculated.

2. The single-photon source anti-focusing measurement device according to claim 1, characterized in that, The signal triggering optical path module includes a visible light optical fiber path, a near-infrared optical fiber path, a first coupling filter optical path, and a second coupling filter optical path, wherein... The fiber input end of the visible light fiber optic path is connected to the single-photon source module via a fiber optic patch cord, and its fiber output end is connected to the first gated single-photon detector via a fiber optic patch cord. The visible light fiber optic path is used to couple and filter signal photons into signal photons of visible light wavelength and output them to the first gated single-photon detector. The fiber input end of the near-infrared optical fiber path is connected to the single-photon source module via an optical fiber patch cord, and its fiber output end is connected to the second gated single-photon detector via an optical fiber patch cord. The near-infrared optical fiber path is used to couple and filter signal photons into signal photons with near-infrared wavelengths and output them to the second gated single-photon detector. The spatial light input end of the first coupled filtering optical path is connected to the single-photon source module via an optical fiber jumper, and its optical fiber output end is connected to the first gated single-photon detector via an optical fiber jumper. The first coupled filtering optical path couples and filters the signal photons of the spatial light signal into signal photons of the optical fiber signal in the wavelength range of 650~1050nm, and outputs them to the first gated single-photon detector. The spatial light input end of the second coupling filter optical path is connected to the single-photon source module via an optical fiber patch cord, and its optical fiber output end is connected to the second gated single-photon detector via an optical fiber patch cord. The second coupling filter optical path couples and filters the signal photons of the spatial light signal into signal photons of the optical fiber signal in the wavelength range of 1050~1650nm, and outputs them to the second gated single-photon detector.

3. The single-photon source anti-focusing measurement device according to claim 1, characterized in that, The interference optical path module includes a coupling filter unit and a polarization beam splitter unit. The coupling filter unit has one spatial light input end and two fiber output ends, and the polarization beam splitter unit has six fiber input ends and six pairs of fiber output ends. The coupling filtering unit includes a third coupling filtering optical path and a fourth coupling filtering optical path; The polarization beam splitting unit includes six polarization beam splitting branches. Each polarization beam splitting branch includes a bias controller, a beam splitter, and a time delay module. The six polarization beam splitting branches are a first polarization beam splitting branch, a second polarization beam splitting branch, a third polarization beam splitting branch, a fourth polarization beam splitting branch, a fifth polarization beam splitting branch, and a sixth polarization beam splitting branch. The third / fourth coupling filter optical path is connected to any one of the six polarization beam splitting branches via fiber optic jumpers. Any one of the six polarization beam splitting branches is connected to a first / second single-photon detector via fiber optic jumpers. The third coupling and filtering optical path couples and filters the deterministic single-photon / idle photon of the spatial optical signal into deterministic single-photon / idle photons of the fiber optical signal within the wavelength range of 950~1050nm, and inputs them into a polarization splitting branch corresponding to the wavelength of the deterministic single-photon / signal photon. In this polarization splitting branch, the bias controller adjusts the polarization state of the deterministic single-photon / idle photon, and the splitter splits the deterministic single-photon / idle photon after the bias adjustment state into two paths of 50 / 50. One deterministic single-photon / idle photon is output to the first single-photon detector, and the other deterministic single-photon / idle photon is output to the second single-photon detector after time adjustment by the time delay module, so that the two deterministic single-photon / idle photons arrive at the first single-photon detector and the second single-photon detector at the same time. The fourth coupling and filtering optical path couples and filters the deterministic single-photon / idle photon of the spatial optical signal into deterministic single-photon / idle photons of the fiber optical signal within the wavelength range of 1050~1650nm. This deterministic single-photon / signal photon is then input into a polarization splitter branch corresponding to its wavelength. In this polarization splitter branch, a bias controller adjusts the polarization state of the deterministic single-photon / idle photon. The splitter then divides the bias-adjusted deterministic single-photon / idle photon into two paths at a 50 / 50 split. One path of the deterministic single-photon / idle photon is output to the first single-photon detector, while the other path is time-adjusted by a time delay module and output to the second single-photon detector, ensuring that both paths arrive at both detectors simultaneously.

4. The single-photon source anti-focusing measurement device according to claim 1, characterized in that, The interference optical path module outputs the deterministic single photon to the first single photon detector and the second single photon detector, respectively. The first and second single-photon detectors count the photons they receive from the deterministic single photons, obtaining a first photon count N. T Second photon count N R ; The coincidence counting module performs a coincidence count on the first photon count and the second photon count to obtain the first coincidence photon count N. TR ; In the absence of light input, obtain the first dark count N of the first single-photon detector. T dark The second dark count N of the second single-photon detector R dark And to obtain the random coincidence photon count N between the dark count of the first single-photon detector and the total photon count of the second single-photon detector. TR dark,total The random coincidence photon count N between the dark count of the second single-photon detector and the total photon count of the first single-photon detector. TR total,dark The random coincidence photon count N between the dark count of the first single-photon detector and the dark count of the second single-photon detector. TR dark,dark ; According to N T dark N R dark N TR dark,total N TR total,dark N TR dark,dark Count N for the first photon respectively T Second photon count N R and the first coincidence photon count N TR After correction, the first true photon count N is obtained. T true Second real photon count N R true The first true photon count N matches TR true ; Based on the first real photon count N T true Second real photon count N R true The first true photon count N matches TR true The anti-focusing value of the deterministic single-photon source was calculated.

5. The single-photon source anti-focusing measurement device according to claim 4, characterized in that, The first real photon count N is calculated using the following formula. T true Second real photon count N R true The first true photon count N matches TR true ; N T true =N T -N T dark ; N R true =N R -N R dark ; N TR true =N TR - N TR dark,total - N TR total,dark +N TR dark,dark ; The anti-focusing value α1 of a deterministic single-photon source is calculated using the following formula. true : ； Where K1 represents the correction factor, ΔT represents the total counting time, and Δt represents the coincidence counting time gate width.

6. The single-photon source anti-focusing measurement device according to claim 5, characterized in that, The coincidence counting module includes a time delay unit and a time-correlated photon counting unit. The time delay unit is electrically connected to the first single-photon detector and the second single-photon detector. The time delayer adjusts the trigger time delay of the first single-photon detector and the second single-photon detector to make the trigger time delay 0, and the time-correlated photon counting unit is used to perform coincidence counting; Under the condition of zero trigger time delay, the measurement record yields the first photon count N. T Second photon count N R And the first coincident photon count N TR ; Under the conditions of zero trigger time delay and no light input to the first single-photon detector, the first dark count N is obtained by measurement and recording. T dark ; Under the conditions of zero trigger time delay and no light input to the second single-photon detector, the second dark count N was obtained by measurement and recording. R dark ; Under the conditions of zero trigger time delay, no light input to the first single-photon detector, and light input to the second single-photon detector, the random coincidence photon count N between the dark count of the first single-photon detector and the total photon count of the second single-photon detector is measured and recorded. TR dark,total ; Under the conditions of zero trigger time delay, light input to the first single-photon detector, and no light input to the second single-photon detector, the random coincidence photon count N between the total photon count of the first single-photon detector and the dark count of the second single-photon detector is measured and recorded. TR total,dark ; Under conditions where the trigger time delay is 0 and neither the first nor the second single-photon detector has any light input, the random coincidence photon count N between the dark count of the first and second single-photon detectors is measured and recorded. TR dark,dark .

7. The single-photon source anti-focusing measurement device according to claim 1, characterized in that, The first gated single-photon detector and the second gated single-photon detector count the received signal photons to obtain the signal photon count N. G total The first gated single-photon detector and the second gated single-photon detector are identified by the gated single-photon detector designation. The first single-photon detector and the second single-photon detector perform photon detection on the idler photons they receive; The coincidence counting module counts N signal photons. G total The second coincidence photon count N is obtained by performing a coincidence count with the idler photons detected by the first single-photon detector. GT total,total Count N signal photons G total The coincidence count of the idler photons detected by the second single-photon detector is performed to obtain the third coincidence photon count N. GR total,total and the signal photon N G total The idler photons detected by the first single-photon detector and the idler photons detected by the second single-photon detector are used to perform coincidence counting, resulting in a triple coincidence photon count N. GTR total,total,total ; In the absence of light input, among which, Obtain the third dark count N of the gated single-photon detector G dark ; Obtain the random coincidence photon count N between the dark count of the gated single-photon detector and the total photon count of the first single-photon detector. GT dark,total The random coincidence photon count N between the total photon count of the gated single-photon detector and the dark count of the first single-photon detector. GT total,dark The random coincidence photon count N between the dark count of the gated single-photon detector and the dark count of the first single-photon detector. GT dark,dark ; Obtain the random coincidence photon count N between the dark count of the gated single-photon detector and the total photon count of the second single-photon detector. GR dark,total The random coincidence photon count N between the total photon count of the gated single-photon detector and the dark count of the second single-photon detector. GR total,dark The random coincidence photon count N between the dark count of the gated single-photon detector and the dark count of the second single-photon detector. GR dark,dark ; Obtain the random coincidence photon count N between the total photon count of the gated single-photon detector, the total photon count of the first single-photon detector, and the dark count of the second single-photon detector. GTR total,total,dark Obtain the random coincidence photon count N between the total photon count of the gated single-photon detector, the dark count of the first single-photon detector, and the total photon count of the second single-photon detector. GTR total,dark,total Obtain the random coincidence photon count N between the total photon count of the gated single-photon detector, the dark count of the first single-photon detector, and the dark count of the second single-photon detector. GTR total,dark,dark Obtain the random coincidence photon count N between the dark count of the gated single-photon detector, the total photon count of the first single-photon detector, and the total photon count of the second single-photon detector. GTR dark,total,total Obtain the random coincidence photon count N between the dark count of the gated single-photon detector, the total photon count of the first single-photon detector, and the dark count of the second single-photon detector. GTR dark ,total,dark Obtain the random coincidence photon count N between the dark count of the gated single-photon detector, the dark count of the first single-photon detector, and the total photon count of the second single-photon detector. GTR dark, dark,total Obtain the random coincidence photon count N between the dark count of the gated single-photon detector, the dark count of the first single-photon detector, and the dark count of the second single-photon detector. GTR dark,dark,dark ; According to N G dark For N G total The third true photon count N is obtained after correction. G true According to N GT dark,total N GT total,dark and N GT dark,dark For N GT total,total The second true coincident photon count N is obtained by making corrections. GT true According to N GR dark,total N GR total,dark and N GR dark,dark For N GR total,total The correction yields the third true coincident photon count N. GR true According to N GTR total,total,dark N GTR total,dark,total N GTR total, dark,dark N GTR dark,total,total N GTR dark,total,dark N GTR dark, dark,total and N GTR dark, dark,dark For N GTR total,total,total The corrected value is used to obtain the true triple coincidence photon count N. GTR true ; According to the third real photon count N G true The second true coincidence photon count N GT true The third true coincidence photon count N GR true And the true triple coincidence photon count N GTR true The anti-focusing value of the predictive single-photon source was calculated.

8. The single-photon source anti-focusing measurement device according to claim 7, characterized in that, The third real photon count N is calculated using the following formula. G true The second true coincidence photon count N GT true The third true coincidence photon count N GR true And the true triple coincidence photon count N GTR true ; N G true =N G total -N G dark ; N GT true =N GT total,total - N GT dark,total - N GT total, dark +N GT dark, dark ; N GR true =N GR total,total - N GR dark,total - N GR total,dark +N GR dark,dark ; N GTR true =N GTR total,total,total - N GTR total,total,dark - N GTR total,dark,total - N GTR total,dark,dark -N GTR dark,total,total - N GTR dark,total,dark -N GTR dark, dark,total +5N GTR dark, dark,dark ; The anti-focusing value α2 of the predictive single-photon source is calculated using the following formula. true : ； Where K2 represents the correction factor.

9. The single-photon source anti-focusing measurement device according to claim 8, characterized in that, The coincidence counting module includes a time delay unit and a time-correlated photon counting unit. The time delay unit is electrically connected to the first single-photon detector and the second single-photon detector. The time delay device adjusts the trigger time delay of the first single-photon detector and the second single-photon detector so that the trigger time delay is 0; Under the condition of zero trigger time delay, the synchronous measurement records the signal photon count N detected by the first gated single-photon detector / the second gated single-photon detector. G total The time-correlated photon counting unit counts N signal photons, based on the idler photons detected by the first single-photon detector and the idler photons detected by the second single-photon detector. G total The coincidence count of the idler photons detected by the second single-photon detector is performed to obtain the third coincidence photon N. GR total,total and the signal photon N G total The idler photons detected by the first single-photon detector and the idler photons detected by the second single-photon detector are used to perform coincidence counting, resulting in a triple coincidence photon count N. GTR total,total,total .

10. A method for measuring anti-focusing of a single-photon source, characterized in that, The method is applied to the single-photon source anti-focusing measurement device as described in any one of claims 1-9, and the method includes: Acquire deterministic or predictive single photons of different wavelengths; For a deterministic single photon of any wavelength, the deterministic single photon is output to a first single-photon detector and a second single-photon detector through the optical path corresponding to that wavelength. The first single-photon detector and the second single-photon detector count the photons they receive to obtain a photon count result. The photon count result is then subjected to coincidence counting to obtain a first coincidence photon count result. The photon count result and the first coincidence photon count result are corrected using the dark count and random coincidence photon count of the first single-photon detector and the second single-photon detector. Based on the corrected photon count result and the first coincidence photon count result, the anti-focusing value of the deterministic single-photon source is calculated. For any wavelength of predictive single-photon signal, the signal photon in the predictive single-photon signal enters the optical path corresponding to that wavelength and is output to a first gated single-photon detector / a second gated single-photon detector. The first gated single-photon detector / a second gated single-photon detector counts the received signal photons to obtain the signal photon count result. The idler photon in the predictive single-photon signal enters the interference optical path module and is output to the first single-photon detector and the second single-photon detector respectively through the optical path corresponding to that wavelength. The detectors count the idler photons they receive to obtain an idler photon count result. They then perform a coincidence count on the signal photon count result and the idler photon count result to obtain a second coincidence photon count result. The signal photon count result and the second coincidence photon count result are corrected using the dark counts of the first gated single-photon detector / second gated single-photon detector, the first single-photon detector and the second single-photon detector, and the random coincidence photon count. Based on the corrected signal photon count result and the second coincidence photon count result, the anti-focusing value of the predictive single-photon source is calculated.

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