A mid-infrared label single photon source generation and upconversion detection device

Abstract

The invention discloses a mid-infrared label single photon source generation and up-conversion detection device, which relates to the field of quantum optical technology and comprises a pump laser module, a quantum light source generation module, an idler photon collection module, a sum frequency up-conversion module and a photon detection and coincidence module; the pump laser module provides pump light for a spontaneous parametric down-conversion process; the quantum light source generation module adopts a PPLN crystal to realize a spontaneous parametric down-conversion process to generate non-degenerate signal photons and idler photon pairs; the idler photons are reflected by a dichroic mirror and enter the idler photon collection module; the invention is based on a degenerate spontaneous parametric down-conversion process and combines quantum frequency up-conversion technology to realize high-efficiency photon up-conversion detection while being able to be tuned by temperature or pump wavelength to realize tuning of the generated mid-infrared photon frequency, and the invention will bring great convenience to applications such as precision measurement based on mid-infrared.

Description

Technical Field

[0001] The invention relates to the technical field of quantum optics, and in particular to a mid-infrared label single photon source generation and up-conversion detection device. Background Art

[0002] Quantum single photon sources are an indispensable part of quantum computing, quantum communication, quantum imaging and other fields. At present, the wavelengths of quantum single photon sources are mainly concentrated in the visible light and near-infrared bands, while traditional mid-infrared technology has played a significant role in optical measurement, optical communication, optical imaging and other fields. Extending single photon sources to the mid-infrared band to realize infrared quantum communication, quantum imaging and other applications will enable mankind to leap into a new era of quantum technology.

[0003] At present, the main methods for generating labeled single photon sources are spontaneous parametric down-conversion and spontaneous four-wave mixing. The spontaneous four-wave mixing process is mostly in the optical fiber system, but the existing mid-infrared band has problems such as immature optical fiber technology and high cost. In addition, the overall photon generation efficiency of the spontaneous four-wave mixing process is low, and the noise is large due to the influence of Raman scattering, Brillouin scattering, etc.

[0004] The spontaneous parametric down-conversion process is mainly based on the second-order nonlinear effect of nonlinear crystals, which requires phase matching conditions to be met, but in reality, phase matching conditions can only be achieved under limited conditions. Armstrong et al. first proposed the quasi-phase matching technology in 1962. By periodically flipping the crystal's electric chips, the phase mismatch between the vector pump light, the idler light and the signal light is introduced to meet the phase matching conditions and ensure the generation of efficient nonlinear effects. However, it is difficult to perform periodic polarization on commonly used mid-infrared nonlinear crystals such as AGS.

[0005] In past research, single photon sources were prepared in the visible and near-infrared bands using various nonlinear crystals such as PPLN, PPKTP, BBO, etc., but photon sources in the mid-infrared field are quite scarce. Recently, Yong Meng Sua et al. used PPLN waveguides to obtain relevant photons in the mid-infrared band. However, the waveguide process is complicated, and special customization is required for mid-infrared applications, and pulse synchronization is required when using pulsed light pumping. At the same time, the cost of single photon detection in the mid-infrared band is extremely high, and the related technology is very immature. Upconversion detection is an effective means to migrate the mid-infrared band to the near-infrared band where mature detection technology is already available for detection.

[0006] Therefore, proposing a low-cost mid-infrared single photon source generation and detection method has important research and application significance. Summary of the invention

[0007] The purpose of the present invention is to provide a mid-infrared label single photon source generation and up-conversion detection device, solve the technical problem of difficulty in mid-infrared photon detection, and propose a mid-infrared related photon up-conversion detection device.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A mid-infrared label single photon source generation and up-conversion detection device, comprising a pump laser module, a quantum light source generation module, an idler photon collection module, a sum frequency up-conversion module and a photon detection and coincidence module;

[0010] The pump laser module provides pump light for the spontaneous parametric down-conversion process;

[0011] The quantum light source generation module uses PPLN crystal to realize the spontaneous parametric down-conversion process to generate non-degenerate signal photon and idler photon pairs; the idler photons are reflected by the dichroic mirror and enter the idler photon collection module, and the signal photons pass through the dichroic mirror and enter the sum frequency up-conversion module;

[0012] The idler photon collection module collects the filtered photons into the optical fiber and transmits them to the photon detection and coincidence module.

[0013] As a further solution of the present invention: the pump laser module includes a single-frequency continuous pump laser, a long-pass filter, a short-pass filter, a half-wave plate, a polarization beam splitter and a half-wave plate 1, which are arranged in sequence from left to right;

[0014] The long-pass filter and the short-pass filter are used to eliminate the photon noise generated by the single-frequency continuous pump laser; the half-wave plate and half-wave plate 1 are used to adjust the output polarization of the single-frequency continuous pump laser; the polarization beam splitter and the half-wave plate are used in conjunction with each other to control the optical power entering the quantum light source generation module and ensure that the light input into the quantum light source generation module is linearly polarized.

[0015] As a further solution of the present invention: the quantum light source generation module includes a focusing lens group, a PPLN crystal, a dichroic mirror, a collimating lens and a mid-infrared bandpass filter arranged in sequence from left to right;

[0016] The focusing lens group is used to focus the laser input into the quantum light source module into the PPLN crystal; the dichroic mirror is used to separate the non-degenerate photon pairs generated in the PPLN crystal; the collimating lens is used to collimate the photons generated in the PPLN crystal; and the mid-infrared bandpass filter is used to filter out the residual pump light and the noise photons generated in the PPLN crystal.

[0017] As a further solution of the present invention: the signal photons are mid-infrared photons, and the idler photons are near-infrared photons.

[0018] As a further solution of the present invention: the idle photon collection module comprises a long-pass filter plate 1, a collimating lens group, a fiber collimator 1, a fiber collimator, a grating and a fiber collimator 2 which are arranged in sequence from the dichroic mirror; the fiber collimator, the grating and the fiber collimator 2 together constitute an idle photon filtering module, which filters the idle photons, and the filtered idle photons are collected into the optical fiber;

[0019] The long-pass filter 1 is used to filter out noise photons in the short-wave band, the collimating lens group is used to collimate the photons and collect them into the optical fiber collimator 1; the grating is used for narrow-band filtering; the optical fiber collimator 1 and the optical fiber collimator 2 are both connected to the optical fiber and are used to transfer the photons to the optical fiber.

[0020] As a further solution of the present invention: the sum frequency up-conversion module includes a focusing lens, a dichroic mirror 1, an up-conversion pump light source module, a PPLN crystal 1, a dichroic mirror 2, a collimating lens 1, a short-pass filter 1, a band-pass filter 1, a fiber collimator 3 and an absorption cell, which are arranged in sequence from left to right; the mid-infrared photons generated by the quantum light source generation module are up-converted to the visible band for detection;

[0021] As a further solution of the present invention: the up-conversion pump light source module is placed at 45 degrees to the first dichroic mirror, and includes an ytterbium-doped fiber amplifier, a second bandpass filter and a first focusing lens which are placed in sequence.

[0022] As a further solution of the present invention: the up-conversion pump laser generated by the ytterbium-doped fiber amplifier and the signal light generated by the quantum light source generation module are combined at a dichroic mirror.

[0023] As a further solution of the present invention: the upconversion pump laser and the upconversion signal light generated in the upconversion process are separated at two dichroic mirrors, the upconversion pump laser is transmitted into the absorption cell, the upconversion signal light is reflected; and the upconversion signal light is collected into the optical fiber.

[0024] As a further solution of the present invention: the photon detection and coincidence module includes a single photon detector 1, a single photon detector 2 and a coincidence counting module;

[0025] The single photon detector 1 is used to detect the collected idler photons; the single photon detector 2 is used to detect the collected signal photons; and the coincidence counting module is used to perform coincidence measurement on the signals of the single photon detector 1 and the single photon detector 2.

[0026] Beneficial effects of the present invention:

[0027] The present invention is based on the non-degenerate spontaneous parametric down-conversion process, generates correlated photon pairs with a high spectral span, obtains a labeled single photon source in the mid-infrared band, and expands the single photon source to the mid-infrared band with broad application prospects; combined with quantum frequency up-conversion technology, while achieving high-efficiency photon up-conversion detection, it can be tuned by temperature or pump wavelength to achieve tuning of the frequency of mid-infrared photons, which will bring great convenience to applications such as precision measurement based on mid-infrared. Based on up-conversion detection technology, it solves the problem of difficulty in detecting mid-infrared photons; the present invention is simple, effective, and easy to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Figure 1 The diagram is a schematic diagram of the optical path structure corresponding to the mid-infrared band marking single-photon source generating device and the mid-infrared single-photon measuring device of the present invention.

[0030] Figure 2 This is the consistent measurement result of the single-photon source marked in the mid-infrared band of the present invention.

[0031] Figure 3 The present invention calculates the variation of polarization period in the spontaneous parametric down-conversion process with the wavelength of mid-infrared photons.

[0032] Figure 4 The present invention calculates and frequency up-conversion process polarization period changes with the wavelength of mid-infrared photons.

[0033] In the figure: 1, single frequency continuous pump laser; 2, long pass filter; 3, short pass filter; 4, half wave plate; 5, polarization beam splitter; 6, half wave plate 1; 7, focusing lens group; 8, PPLN crystal; 9, dichroic mirror; 10, collimating lens group; 11, grating; 12, collimating lens; 13, mid-infrared band pass filter; 14, focusing lens; 15, dichroic mirror 1; 16, focusing lens 1; 17, band pass filter 2; 18. Ytterbium-doped fiber amplifier; 19. PPLN crystal 1; 20. Dichroic mirror 2; 21. Collimating lens 1; 22. Short-pass filter 1; 23. Band-pass filter 1; 24. Fiber collimator 3; 25. Coincidence counting module; 26. Absorption cell; 27. Fiber collimator 1; 28. Fiber collimator; 29. ​​Fiber collimator 2; 30. Long-pass filter 1; 31. Single-photon detector 2; 32. Single-photon detector 1. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The present invention is an infrared single-photon quantum light source generation and detection device based on spontaneous parametric down-conversion (SPDC), which has the characteristics of easy detection of trigger signal photons and tunable infrared photon wavelengths. In addition, the infrared photon up-conversion detection technology is proposed to solve the problem that the current infrared direct detector requires deep refrigeration.

[0036] Example 1

[0037] See also Figure 1 As shown, it includes a pump laser module, a quantum light source generation module, an idler photon collection module, a sum frequency up-conversion module and a photon detection and coincidence module;

[0038] The pump laser module provides pump light for the spontaneous parametric down-conversion process;

[0039] The quantum light source generation module uses a PPLN crystal 8 to realize a spontaneous parametric down-conversion process to generate non-degenerate signal photon and idler photon pairs; the idler photons are reflected by a dichroic mirror and enter the idler photon collection module, and the signal photons pass through the dichroic mirror and enter the sum frequency up-conversion module; the signal photons are mid-infrared photons, and the idler photons are near-infrared photons;

[0040] The idler photon collection module collects the filtered photons into the optical fiber and transmits them to the photon detection and coincidence module.

[0041] The pump laser module includes a 780nm single-frequency continuous pump laser 1, a long-pass filter 2, a short-pass filter 3, a half-wave plate 4, a polarization beam splitter 5 and a half-wave plate 6, which are arranged from left to right in sequence;

[0042] The 780nm single-frequency continuous pump laser 1, with a central wavelength of 780.022nm, is used as the pump light for the SPDC process in the PPLN crystal in this example;

[0043] The long-pass filter 2 is a 790nm long-pass filter, and the short-pass filter 3 is an 850nm short-pass filter. This filter set is used to eliminate the photon noise generated by the 780nm single-frequency continuous pump laser 1;

[0044] The half-wave plate 4 is a half-wave plate operating at 780nm and is used to adjust the output polarization of the 780nm single-frequency continuous pump laser 1;

[0045] The polarization beam splitter 5 is a polarization-dependent beam splitter operating at 780 nm. The polarization beam splitter 5 cooperates with the half-wave plate 4 to control the optical power entering the quantum light source generation module and ensure that the light input into the quantum light source generation module is linearly polarized.

[0046] The half-wave plate 6 is a half-wave plate operating at 780nm and is used to adjust the polarization of the 780nm light entering the SPDC module.

[0047] The quantum light source generation module includes a focusing lens group 7, a PPLN crystal 8, a dichroic mirror 9, a collimating lens 12 and a mid-infrared bandpass filter 13 arranged in sequence from left to right;

[0048] The focusing lens group 7 is composed of two plano-convex lenses with a focal length of 75 mm and a spacing of 210 mm, which work at 780 nm. It is used to focus the 780 nm laser input into the quantum light source module into the PPLN crystal 8.

[0049] The PPLN crystal 8 is a periodically polarized magnesium oxide-doped lithium niobate (MgO:PPLN) crystal with a polarization period of 21.3um and a length of 30mm. It is coated with 780nm to 1000nm and 3000 to 5000nm anti-reflection films at both ends. It is used to perform a type-0 quasi-phase-matched SPDC process under the action of a 780.022nm pump laser to generate mid-infrared non-degenerate photon pairs, which are divided into near-infrared idler photons and mid-infrared signal photons. The crystal is placed in a precision temperature-controlled furnace with an accuracy of 0.1mk. In this example, the crystal temperature is stabilized at 85°C, and the wavelengths of the related photon pairs generated are 3390nm and 1013nm respectively.

[0050] The dichroic mirror 9 is a dichroic mirror that transmits mid-infrared light and reflects near-infrared light, and is used to separate the non-degenerate photon pairs generated in the PPLN crystal 8, wherein the 1013nm photons are reflected at 90° into the idler light collection module, and the 3390nm photons pass through the dichroic mirror 9;

[0051] The collimating lens 12 is a calcium fluoride lens with a focal length of 200 mm, which is used to collimate the 3390 nm photons generated in the PPLN crystal 8;

[0052] The mid-infrared bandpass filter 13 is a 3400-500nm bandpass filter, which is used to filter out the residual 780nm pump light and the noise photons generated in the PPLN crystal 8. The 3390nm photons pass through the filter and enter the sum frequency up-conversion module.

[0053] The idler photon collection module includes a long pass filter 30, a collimating lens group 10, a fiber collimator 27, a fiber collimator 28, a grating 11 and a fiber collimator 29 which are arranged in sequence from a dichroic mirror 9;

[0054] Among them, the long-pass filter 30 is a 1000nm long-pass filter, which is used to filter out noise photons in other short-wave bands that are irrelevant to the 1013nm-3390nm photon pairs generated by the SPDC process;

[0055] The collimating lens group 10 is composed of two plano-convex lenses with a focal length of 75 mm working at 1013 nm, with a spacing of 200 mm, which are used to collimate the 1013 nm photons generated by the SPDC process and collect them into the optical fiber collimator 27;

[0056] Fiber collimator 27 is a fiber collimator operating at 1013 nm, which is connected to the optical fiber and transfers the 1013 nm photons input in space to the optical fiber;

[0057] The fiber collimator 28, the grating 11 and the fiber collimator 29 together constitute an idler photon filtering module, wherein the fiber collimator 28 is a fiber collimator operating at 1013nm, and is used to output 1013nm related photons, and the grating 11 is a grating operating at 1um and 600 / mm line, and is used to perform narrow-band filtering on the 1013nm correlation to improve the coincidence measurement signal-to-noise ratio, and the filtering bandwidth is 0.4nm, and the fiber collimator 29 is a fiber collimator operating at 1013nm, and is used to collect the filtered 1013nm related photons into the optical fiber and transmit them to the photon detection and coincidence module.

[0058] The sum frequency up-conversion module includes a focusing lens 14, a dichroic mirror 15, an up-conversion pump light source module, a PPLN crystal 19, a dichroic mirror 20, a collimating lens 21, a short-pass filter 22, a band-pass filter 23, a fiber collimator 3 24 and an absorption cell 26, which are arranged in sequence from left to right.

[0059] The focusing lens 14 is a calcium fluoride lens with a focal length of 150 mm working in the mid-infrared band, and is used to focus the 3390 nm related photons into the PPLN crystal 19;

[0060] The second dichroic mirror 20 is a dichroic mirror that transmits mid-infrared light and reflects near-infrared light, and is used to combine the 3390nm related signal photons of the quantum light source module with the 1064nm pump light of the upconversion pump light source module;

[0061] The up-conversion pump light source module is placed at 45 degrees with the dichroic mirror 15, and includes an ytterbium-doped fiber amplifier 18, a bandpass filter 17 and a focusing lens 16 which are placed in sequence;

[0062] The Ytterbium-doped fiber amplifier 18 has a maximum output power of 20 W and generates a 1064 nm laser as pump light for the sum frequency up-conversion process;

[0063] The up-conversion pump laser generated by the ytterbium-doped fiber amplifier 18 and the signal light generated by the quantum light source generation module are combined at the dichroic mirror 15 .

[0064] The second bandpass filter 17 is a 1064-10 nm bandpass filter, which is used to filter out noise photons generated by the ytterbium-doped fiber amplifier 18.

[0065] The focusing lens 16 is a lens with a focal length of 100 mm and operates at 1064 nm. It is used to focus the 1064 nm laser into the PPLN crystal 19;

[0066] The PPLN crystal 19 is a periodically polarized magnesium oxide-doped lithium niobate (MgO:PPLN) crystal with a polarization period of 22.7um and a length of 40mm. It is coated with 780nm to 1000nm and 3000 to 5000nm anti-reflection films at both ends. It is used to perform a type-0 quasi-phase-matched sum frequency generation (SFG) up-conversion process under the action of a 1064nm pump laser and a 3390nm mid-infrared photon to generate visible band photons, which retain the quantum characteristics of the input mid-infrared photons and still form a related photon pair with the idler photons of the corresponding near-infrared band. The crystal is placed in a precision temperature-controlled furnace with an accuracy of 0.1mk. In this example, the crystal temperature is stabilized at 20°C, and the wavelength of the generated visible band photons is 809.82nm.

[0067] The second dichroic mirror 20 is a 950nm long-pass dichroic mirror, which separates the up-converted 809nm signal photons from the 1064nm up-conversion pump laser, wherein the 809nm signal photons are vertically reflected and the 1064nm up-conversion pump laser passes through the dichroic mirror.

[0068] The absorption cell 26 is a black metal box, which is used to absorb the strong 1064 nm pump laser that passes through the dichroic mirror 20.

[0069] The collimating lens 21 is a lens with a focal length of 200nm and working at 810nm, and is used to collimate the divergent 810nm signal light generated in the PPLN crystal 19;

[0070] The short-pass filter 22 is a 1000nm short-pass filter, which is used to filter out the 1064nm pump laser and other stray photon noise;

[0071] The bandpass filter 23 is a 810-10nm bandpass filter, which is used to further filter out the 1064nm pump laser and other stray photon noise;

[0072] The fiber collimator 3 24 is a fiber collimator operating at 810 nm, which is connected to the optical fiber and transfers the 810 nm signal photons input in space to the optical fiber.

[0073] The up-conversion pump laser and the up-conversion signal light generated in the up-conversion process are separated at the second dichroic mirror 20, the up-conversion pump laser is transmitted into the absorption cell 26, and the up-conversion signal light is reflected.

[0074] The photon detection and coincidence module includes a single photon detector 1 32, a single photon detector 2 31 and a coincidence counting module 25;

[0075] The single-photon detector 1 32 is a silicon avalanche diode single-photon detector, whose operating band is visible to near-infrared, and is used to detect the collected 1013nm idler photons; the single-photon detector 2 31 is a silicon avalanche diode single-photon detector, whose operating band is visible to near-infrared, and is used to detect the collected 810nm signal photons; the coincidence counting module 25 is used to perform coincidence measurement on the signals of the single-photon detector 1 32 and the single-photon detector 2 31.

[0076] Example 1 meets the measurement results under the conditions of 780nm pump light power of 4.2mw and 1064nm pump light power of 5.58mw as shown in the attached figure. Figure 2 shown.

[0077] Example 2

[0078] Based on implementation one, in order to realize a mid-infrared band labeled single-photon source generating device and a mid-infrared single-photon measuring device, through the design provided in implementation two, wide-spectrum tuned mid-infrared photons can be obtained and corresponding up-conversion measurements can be performed.

[0079] As another embodiment provided by the present invention, preferably, the design to be completed first is to determine the crystal parameters for generating the required mid-infrared photons.

[0080] Common periodically poled crystals used for quasi-phase matching (QPM) include PPLN, PPLT, PPKTP, PPRTA, etc. At present, the most common working material for realizing quasi-phase matching optical parametric generator (QPM-OPG) is lithium niobate (LiNbO3) crystal, which is the most ideal ferroelectric material. The crystal has a wide light transmission range of about 0.4~4.5µm, covering the near and mid-infrared regions, and has a large nonlinear coefficient (d33=42pm / V). Since LiNbO3 crystal has a low laser damage threshold, is prone to light damage, and is sensitive to thermal effects, it is difficult to achieve high power output at room temperature, which limits its application. In view of this, we used MgO (5mol%) doped periodically poled lithium niobate crystal (PPMgLN) in the experiment to improve its resistance to light damage, and its damage threshold is 100 times higher than that of PPLN. Due to the limitation of the electric field breakdown threshold, the thickness of PPLN crystal can generally only be about 1mm. In order to eliminate the influence of photorefractive damage, PPLN crystal can only work at about 150℃.

[0081] Nonlinear crystals are important media for generating entangled photons. In order to generate the nW-level entangled photon source required for this project, the required nonlinear crystals should meet the requirements of high nonlinear coefficient, high damage threshold, wide spectral transmission, small absorption coefficient, stable physical and chemical properties, good processing technology, and mechanical parameters suitable for engineering applications.

[0082] According to the design requirements, it is necessary to output entangled photon pairs of 891nm~1054nm and 3mm~5mm. This requires designing the period of the crystal at a certain temperature and using the period reversal of the crystal to achieve gain amplification of the related photons in the required band. By reversing the crystal period every odd multiples, the coherent superposition of the related light can be enhanced. After the e-polarized fundamental frequency light with a circular frequency of ωp enters the crystal, it interacts with the phonons of the crystal and spontaneously splits into two related photons. To achieve quasi-phase matching of the crystal, the following two equations must be satisfied:

[0083] ;

[0084] is the phase mismatch of the three waves during propagation, are the wavelengths of pump light, signal light and idler light, respectively. are the wave loss of pump light, signal light and idle light respectively. The phase shift introduced by periodic polarization is the crystal period that satisfies the first-order quasi-phase matching: in, Represent the refractive index of pump light, signal light and idle light in the crystal respectively. The refractive index of the e-polarized pump light in the PPLN crystal is It can be expressed by the Sellmeier equation as: ;

[0085] in are all fixed coefficients. In formula (4), f is a temperature-related function. The specific expression is shown in formula (5). is the wavelength, is a fixed temperature coefficient, is the actual temperature.

[0086] For the spontaneous parametric down-conversion process, the polarization period varies with the wavelength of the mid-infrared photons at 780 nm pump and 85 °C as shown in the attached figure. Figure 3 shown.

[0087] Furthermore, for the sum frequency up-conversion detection process, the polarization period is calculated to vary with the wavelength of the mid-infrared photons at 1064 nm pump and 20 °C as shown in the attached figure. Figure 4 shown.

[0088] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A mid-infrared label single photon source generation and up-conversion detection device, characterized in that: It includes pump laser module, quantum light source generation module, idler photon collection module, sum frequency up-conversion module and photon detection and coincidence module; The pump laser module provides pump light for the spontaneous parametric down-conversion process; The quantum light source generation module uses PPLN crystal to realize the spontaneous parametric down-conversion process to generate non-degenerate signal photon and idler photon pairs; the idler photons are reflected by the dichroic mirror and enter the idler photon collection module, and the signal photons pass through the dichroic mirror and enter the sum frequency up-conversion module; The idler photon collection module collects the filtered photons into the optical fiber and transmits them to the photon detection and coincidence module; The sum frequency up-conversion module comprises, arranged from left to right in sequence, a focusing lens (14), a dichroic mirror 1 (15), an up-conversion pump light source module, a PPLN crystal 1 (19), a dichroic mirror 2 (20), a collimating lens 1 (21), a short-pass filter 1 (22), a band-pass filter 1 (23), a fiber collimator 3 (24), and an absorption cell (26).

2. A mid-infrared label single photon source generation and up-conversion detection device according to claim 1, characterized in that: The pump laser module comprises a single-frequency continuous pump laser (1), a long-pass filter (2), a short-pass filter (3), a half-wave plate (4), a polarization beam splitter (5) and a half-wave plate 1 (6), which are arranged in sequence from left to right; The long-pass filter (2) and the short-pass filter (3) are used to eliminate photon noise generated by a single-frequency continuous pump laser (1); the half-wave plate (4) and the first half-wave plate (6) are used to adjust the output polarization of the single-frequency continuous pump laser (1); and the polarization beam splitter (5) cooperates with the half-wave plate (4) to control the optical power entering the quantum light source generation module and ensure that the light input into the quantum light source generation module is linearly polarized light.

3. A mid-infrared label single photon source generation and up-conversion detection device according to claim 1, characterized in that: The quantum light source generation module comprises a focusing lens group (7), a PPLN crystal (8), a dichroic mirror (9), a collimating lens (12) and a mid-infrared bandpass filter (13) which are arranged in sequence from left to right; The focusing lens group (7) is used to focus the laser light input into the quantum light source module into the PPLN crystal (8); the dichroic mirror (9) is used to separate the non-degenerate photon pairs generated in the PPLN crystal (8); the collimating lens (12) is used to collimate the photons generated in the PPLN crystal (8); and the mid-infrared bandpass filter (13) is used to filter out residual pump light and noise photons generated in the PPLN crystal (8).

4. A mid-infrared label single photon source generation and up-conversion detection device according to claim 1, characterized in that: The signal photons are mid-infrared photons, and the idler photons are near-infrared photons.

5. A mid-infrared label single photon source generation and up-conversion detection device according to claim 1, characterized in that: The idler photon collection module comprises a long-pass filter (30), a collimating lens group (10), a fiber collimator (27), a fiber collimator (28), a grating (11) and a fiber collimator (29) which are arranged in sequence from a dichroic mirror (9); The long-pass filter plate 1 (30) is used to filter out noise photons in the short-wave band, the collimating lens group (10) is used to collimate the photons and collect them into the optical fiber collimator 1 (27); the grating (11) is used for narrow-band filtering; the optical fiber collimator 1 (27) and the optical fiber collimator 2 (29) are both connected to the optical fiber and are used to transfer the photons to the optical fiber.

6. A mid-infrared label single photon source generation and up-conversion detection device according to claim 1, characterized in that: The up-conversion pump light source module is placed at 45 degrees to the dichroic mirror 1 (15), and comprises an ytterbium-doped optical fiber amplifier (18), a bandpass filter 2 (17) and a focusing lens 1 (16) which are placed in sequence.

7. A mid-infrared label single photon source generation and up-conversion detection device according to claim 6, characterized in that: The up-conversion pump laser generated by the ytterbium-doped fiber amplifier (18) and the signal light generated by the quantum light source generation module are combined at the dichroic mirror 1 (15).

8. A mid-infrared label single photon source generation and up-conversion detection device according to claim 7, characterized in that: The up-conversion pump laser and the up-conversion signal light generated in the up-conversion process are separated at the second dichroic mirror (20), the up-conversion pump laser is transmitted into the absorption pool (26), and the up-conversion signal light is reflected.

9. A mid-infrared label single photon source generation and up-conversion detection device according to claim 1, characterized in that: The photon detection and coincidence module comprises a single photon detector 1 (32), a single photon detector 2 (31) and a coincidence counting module (25); The single photon detector one (32) is used to detect collected idler photons; the single photon detector two (31) is used to detect collected signal photons; and the coincidence counting module (25) is used to perform coincidence measurement on the signals of the single photon detector one (32) and the single photon detector two (31).

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