Optical curing type Sagnac ring and compact entanglement source

Abstract

The utility model relates to an optical curing type Sagnac ring and a compact entanglement source, and belongs to the technical field of quantum information. The compact entanglement source comprises a fixed bottom plate, a collimator, a filter, a dichroscope, a first polarization beam splitter prism, a first half-wave plate, a first reflector, a second reflector, a periodically poled potassium titanyl phosphate crystal, a first spherical lens, a second spherical lens, a third spherical lens and a fourth spherical lens, according to the optical curing type Sagnac ring formed by the above devices, the optical element is permanently fixed on the bottom plate through a high-precision optical bonding technology, the influence of mechanical vibration of the surrounding environment on the precision of the Sagnac type entanglement source can be greatly reduced, frequent maintenance of the entanglement source is avoided, and the space occupation of the Sagnac type entanglement source system is effectively reduced. In conclusion, the stability of the Sagnac type entanglement source system is improved, and a foundation is laid for a miniaturized device-independent quantum random number generator.

Description

TECHNICAL FIELD

[0001] The utility model relates to quantum information technology field especially relates to a kind of optical solidification formula Sagnac ring and compact entanglement source. BACKGROUND

[0002] The current common periodic polarization entanglement source structure based on spontaneous parametric down-conversion mainly has Sagnac type and Beam Displacer type two, wherein Sagnac type utilizes the characteristics of PPKTP crystal collinear output, generates down-conversion entangled photon pairs from the positive and negative directions respectively, to form polarization entanglement structure. Beam Displacer type utilizes the characteristics of birefringent crystal that can decompose different polarization components in light beam, makes its horizontal and vertical components propagate along different paths in the same horizontal plane, and realizes entanglement by combining Mach-Zehnder interferometer structure. Compared with the above, Sagnac type has the advantage of stable two-arm phase difference, and the structure is more stable, so people adopt this structure more.

[0003] However, the space occupied by the spatial light path of the current Sagnac type entanglement source is large, and the mechanical vibration of the surrounding environment is high, so it needs to be adjusted and maintained regularly, which is not conducive to the miniaturization and practicality of the system. That is, the current Sagnac type entanglement source has the technical problems of large size and frequent maintenance. SUMMARY

[0004] In view of the above technical problems, the utility model provides an optical solidification formula Sagnac ring and compact entanglement source to solve the technical problems of large size and frequent maintenance of the existing Sagnac type entanglement source.

[0005] In the first aspect, the utility model provides an optical solidification formula Sagnac ring, comprising: fixed bottom plate, collimator, filter, dichroic mirror, first polarization beam splitter prism, first half wave plate, first mirror, second mirror, periodic polarization potassium titanyl phosphate crystal, first spherical lens, second spherical lens, third spherical lens and fourth spherical lens;

[0006] The collimator, the filter, the dichroic mirror, the first polarization beam splitter prism, the first half wave plate, the first mirror, the second mirror, the periodic polarization potassium titanyl phosphate crystal, the first spherical lens, the second spherical lens, the third spherical lens and the fourth spherical lens are fixed on the fixed bottom plate by high-precision optical adhesive technology, and the dichroic mirror, the first polarization beam splitter prism, the first half wave plate, the first mirror, the periodic polarization potassium titanyl phosphate crystal and the second mirror are arranged to form a Sagnac ring structure;

[0007] The filter is arranged between the collimator and the dichroic mirror, and the first entangled photon output by the Sagnac ring structure reaches the first output end of the optical solidification Sagnac ring after passing through the first spherical lens and the second spherical lens, and the second entangled photon output by the Sagnac ring structure reaches the second output end of the optical solidification Sagnac ring after passing through the third spherical lens and the fourth spherical lens.

[0008] Optionally, in the Sagnac ring structure, the dichroic mirror and the first polarization beam splitting prism are arranged as follows:

[0009] When the collimator emits light, the light enters the light-transmitting surface of the dichroic mirror at an angle of 45 degrees after passing through the filter, and enters the first polarization beam splitting prism at an angle of 45 degrees with the interference film in the first polarization beam splitting prism after penetrating the dichroic mirror, and the light is divided into horizontal polarization light and vertical polarization light by the first polarization beam splitting prism.

[0010] Optionally, in the Sagnac ring structure, the first half-wave plate, the first mirror, the second mirror and the periodically poled potassium titanyl phosphate crystal are arranged as follows:

[0011] The horizontal polarization light enters one end of the periodically poled potassium titanyl phosphate crystal after passing through the first half-wave plate and being reflected by the first mirror, the vertical polarization light enters the other end of the periodically poled potassium titanyl phosphate crystal after being reflected by the second mirror, and the light entering the two ends of the periodically poled potassium titanyl phosphate crystal is in the same straight line.

[0012] Optionally, the beam waist diameter of the light emitted by the collimator is 0.36-0.4mm.

[0013] Optionally, the first spherical lens and the third spherical lens are plano-convex spherical mirrors, and the second spherical lens and the fourth spherical lens are plano-concave spherical mirrors.

[0014] In a second aspect, the utility model also provides a compact entanglement source, including any one of the optical solidification Sagnac ring, still including pump module and collection module;

[0015] The output end of the pump module is connected with the input end of the optical solidification Sagnac ring, and the input end of the optical solidification Sagnac ring is connected with the collimator.

[0016] Optionally, the pump module comprises a pump laser and a first polarization controller.

[0017] The pump laser emits pump light to the input end of the first polarization controller, and the output end of the first polarization controller is connected to the output end of the pump module.

[0018] Optionally, the collection module comprises a first collection sub-module and a second collection sub-module.

[0019] The first collection sub-module comprises a second half-wave plate, a second polarization beam splitter prism, a first aspherical lens and a first collector, and the first entangled photons output by the first output end of the optical solidified Sagnac ring are sequentially input into the first collector through the second half-wave plate, the second polarization beam splitter prism and the first aspherical lens.

[0020] The second collection sub-module comprises a third half-wave plate, a third polarization beam splitter prism, a second aspherical lens and a second collector, and the second entangled photons output by the second output end of the optical solidified Sagnac ring are sequentially input into the second collector through the third half-wave plate, the third polarization beam splitter prism and the second aspherical lens.

[0021] Optionally, the collection module further comprises a second polarization controller and a third polarization controller.

[0022] The output end of the first collector is connected to the input end of the second polarization controller, and the output end of the second collector is connected to the input end of the third polarization controller.

[0023] The above scheme has the following beneficial effects:

[0024] In the optical solidified Sagnac ring, optical elements are permanently fixed on a bottom plate through high-precision optical adhesive technology, so that the influence of mechanical vibration of the surrounding environment on the precision of the Sagnac entanglement source can be greatly reduced, frequent maintenance of the entanglement source is avoided, and the space occupation of the Sagnac entanglement source system is effectively reduced. In summary, the optical solidified Sagnac ring improves the stability of the Sagnac entanglement source system and lays a foundation for a miniaturized device-independent quantum random number generator. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a structure schematic view of the optical solidified Sagnac ring provided by the embodiment one of the utility model;

[0026] Figure 2 is a structure schematic view of a compact entanglement source provided by the embodiment two of the utility model;

[0027] Figure 3 is a temperature change schematic view of the environment in which the compact entanglement source in the embodiment two of the utility model is located in a specific time period;

[0028] Figure 4 is the efficiency change schematic diagram of the compact entanglement source in the specific time period of Alice measurement end in the embodiment two of the utility model;

[0029] Figure 5 is the efficiency change schematic diagram of the compact entanglement source in the specific time period of Bob measurement end in the embodiment two of the utility model;

[0030] The symbols are explained as follows:

[0031] 1, fixed bottom plate; 2, collimator; 3, filter; 4, dichroic mirror; 5, first polarization beam splitter prism; 6, first half-wave plate; 7, first mirror; 8, second mirror; 9, periodical polarization potassium titanyl phosphate crystal; 10, first spherical lens; 11, second spherical lens; 12, third spherical lens; 13, fourth spherical lens; 14, pump laser; 15, first polarization controller; 16, second half-wave plate; 17, second polarization beam splitter prism; 18, first collector; 19, third half-wave plate; 20, third polarization beam splitter prism; 21, second collector; 22, second polarization controller; 23, third polarization controller. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects solved by the utility model more clearly understood, the following will be further described in detail in combination with the drawings and embodiments.

[0033] It should be understood that the embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments and illustrate the best mode contemplated for practicing the embodiments. Upon reading the following description, one skilled in the art will understand how to implement the concepts of the present disclosure and will recognize that the concepts are not limited to the particular embodiments described herein. It should be understood that these concepts and applications fall within the scope of the present disclosure and the following claims.

[0034] It should also be understood that although the terms first, second, etc. can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0035] It should also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements can be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0036] It should also be understood that the terms "upper", "lower", "left", "right", "front", "back", "bottom", "intermediate", "middle", "top", and the like can be used herein to describe various elements as they are oriented in the drawings under discussion. The orientation or position indicated by these terms is based on the orientation or position shown in the drawings under discussion and is used only to facilitate the description of the present application and to simplify the description, and therefore these elements should not be limited by these terms.

[0037] These terms are used only to distinguish one element from another element. For example, a first element can be referred to as an "upper" element, and similarly, a second element can be referred to as an "upper" element according to the relative orientation of these elements, without departing from the scope of the present disclosure.

[0038] It is further understood that the terms "including", "including", "including", and / or "including" as used herein specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0039] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of the specification and relevant art, and should not be interpreted in an idealized or overly formal sense, unless expressly defined herein.

[0040] In embodiment one, an optical curing Sagnac ring as shown in Figure 1 The optical curing Sagnac ring shown in Figure 1 includes a fixed base plate 1, a collimator 2, a filter 3, a dichroic mirror 4, a first polarization beam splitter prism 5, a first half-wave plate 6, a first mirror 7, a second mirror 8, a periodically poled potassium titanyl phosphate crystal 9, a first spherical lens 10, a second spherical lens 11, a third spherical lens 12, and a fourth spherical lens 13. The fixed base plate 1 is represented by a dashed box.

[0041] The collimator 2, the filter 3, the dichroic mirror 4, the first polarization beam splitting prism 5, the first half-wave plate 6, the first mirror 7, the second mirror 8, the periodically poled potassium titanyl phosphate crystal 9, the first spherical lens 10, the second spherical lens 11, the third spherical lens 12 and the fourth spherical lens 13 are fixed on the fixed bottom plate 1 by high-precision optical adhesive technology, and the dichroic mirror 4, the first polarization beam splitting prism 5, the first half-wave plate 6, the first mirror 7, the periodically poled potassium titanyl phosphate crystal 9 and the second mirror 8 form a Sagnac ring structure.

[0042] The filter 3 is arranged between the collimator 2 and the dichroic mirror 4, the first entangled photon output by the Sagnac ring structure passes through the first spherical lens 10 and the second spherical lens 11 and reaches the first output end of the optical solidification Sagnac ring, and the second entangled photon output by the Sagnac ring structure passes through the third spherical lens 12 and the fourth spherical lens 13 and reaches the second output end of the optical solidification Sagnac ring.

[0043] The embodiment takes the optical wavelength input into the optical solidification Sagnac ring as an example for description, as shown in the figure, Figure 1 The collimator 2 collimates the 780nm light input into it into a linear light beam, the linear light beam is filtered by the filter 3 and then enters the transparent surface of the dichroic mirror 4 (DM mirror) (780nm HT, 1560nm HR) at an angle of 45 degrees and penetrates the dichroic mirror 4, then the linear light beam enters the first polarization beam splitting prism 5 at an angle of 45 degrees with the interference film in the first polarization beam splitting prism 5, the light is divided into horizontal polarization light and vertical polarization light by the first polarization beam splitting prism 5, and then the horizontal polarization light and the vertical polarization light respectively enter the PPKTP crystal, that is, the periodically poled potassium titanyl phosphate crystal 9, in the crystal, the horizontal polarization light and the vertical polarization light respectively generate a pair of down-conversion entangled photons, form a polarization entanglement structure, and finally realize the preparation of the entangled photon pair through the interference of the first polarization beam splitting prism 5.

[0044] Preferably, the first polarization beam splitting prism 5 is a 780nm&1560nm dual-wavelength PBS (polarization beam splitting prism), the first half-wave plate 6 is a 780nm half-wave plate, the first mirror 7 and the second mirror 8 are 780nm&1560nm mirrors, the beam waist diameter of the light emitted by the collimator 2 is 0.36-0.4mm, the first spherical lens 10 and the third spherical lens 12 are plano-convex spherical lenses, the second spherical lens 11 and the fourth spherical lens 13 are plano-concave spherical lenses. The fixed bottom plate 1 is preferably a quartz plate, and each device is fixed and arranged on the quartz plate by high-precision optical adhesive technology.

[0045] And, in the optical solidification Sagnac ring, as shown in Figure 1 The first half-wave plate 6, the first mirror 7, the second mirror 8 and the periodically poled potassium titanyl phosphate crystal 9 are arranged as:

[0046] The horizontal polarized light is reflected by the first mirror 7 after passing through the first half-wave plate 6 and is injected into one end of the periodically poled potassium titanyl phosphate crystal 9, the vertical polarized light is reflected by the second mirror 8 and is injected into the other end of the periodically poled potassium titanyl phosphate crystal 9, and the light injected into both ends of the periodically poled potassium titanyl phosphate crystal 9 is in the same straight line, so that the horizontal polarized light and the vertical polarized light can occur spontaneous parametric down-conversion in the PPKTP crystal, and the generated two-photon pairs are respectively output as the first entangled light output end and the second entangled light output end of the Sagnac ring structure through the first polarization beam splitter prism 5 and the dichroic mirror 4 (DM mirror), and the first entangled photon output by the Sagnac ring structure reaches the first output end of the optical solidification Sagnac ring after passing through the first spherical lens 10 and the second spherical lens 11, and the second entangled photon output by the Sagnac ring structure reaches the second output end of the optical solidification Sagnac ring after passing through the third spherical lens 12 and the fourth spherical lens 13.

[0047] The optical solidification Sagnac ring in the embodiment actually solidifies the pump and down-conversion light path part of the Sagnac entanglement source system, and adds a spherical lens group originally belonging to the collection module, so that the two output ends output collimated 1560nm entangled light. After the optical solidification Sagnac ring structure is solidified and packaged, the product integration and the convenience of use are improved, the core part Sagnac ring of the entanglement source can be reduced from 15cm to 3cm, so that the space occupied by the entanglement source system can be effectively reduced, and the stability of the entanglement source system is improved, and the miniaturization of the entanglement source is easy. At the same time, a temperature feedback device can be selected to control the temperature of the optical solidification Sagnac ring, further increasing the practicability.

[0048] Based on the optical solidification Sagnac ring in the above embodiment, as shown in Figure 2 In the second embodiment, a compact entanglement source is provided, which comprises the optical solidification Sagnac ring in the above embodiment, and further comprises a pump module and a collection module.

[0049] The output end of the pump module is connected to the input end of the optical solidification Sagnac ring, and the input end of the optical solidification Sagnac ring is connected to the collimator 2.

[0050] The embodiment also takes the input optical wavelength of the optical solidification Sagnac ring as 780 nm as an example for illustration. The function of the pump module is to input 780 nm pump light to the optical solidification Sagnac ring. Therefore, the output end of the pump module needs to be connected to the input end of the optical solidification Sagnac ring, and the input end of the optical solidification Sagnac ring needs to be connected to the collimator 2.

[0051] Specifically, as shown in Figure 2 The embodiment preferably provides a pump module including a pump laser 14 and a first polarization controller 15.

[0052] The pump light emitted by the pump laser 14 is input to the input end of the first polarization controller 15, and the output end of the first polarization controller 15 is connected to the output end of the pump module.

[0053] The pump laser 14 emits 780 nm light in the embodiment. The first polarization controller 15 replaces the combination structure of the quarter-wave plate, the half-wave plate, and the quarter-wave plate arranged in sequence in the existing Sagnac entanglement source. The existing pump module is simplified to a fiber device, further reducing the occupied space. By adjusting the first polarization controller 15 of the pump module, the non-maximum entangled state required for the experiment is prepared as |𝜓> = cosα|HV> + sinα|VH>, and the measured entangled state fidelity is 98.8%.

[0054] In addition, as shown in Figure 2 The embodiment preferably provides a collection module including a first collection sub-module and a second collection sub-module.

[0055] The first collection sub-module includes a second half-wave plate 16, a second polarization beam splitter prism 17, a first aspherical lens, and a first collector 18. The first entangled photons output by the first output end of the optical solidification Sagnac ring pass through the second half-wave plate 16, the second polarization beam splitter prism 17, and the first aspherical lens in sequence, and are input to the first collector 18.

[0056] The second collection sub-module includes a third half-wave plate 19, a third polarization beam splitter prism 20, a second aspherical lens, and a second collector 21. The second entangled photons output by the second output end of the optical solidification Sagnac ring pass through the third half-wave plate 19, the third polarization beam splitter prism 20, and the second aspherical lens in sequence, and are input to the second collector 21.

[0057] Although Figure 2The first aspherical lens and the second aspherical lens are not shown in the two collection sub-modules, but the embodiment is preferably provided with the first aspherical lens in the first collection sub-module and the second aspherical lens in the second collection sub-module to improve the imaging quality and clarity, and the aspherical lens in each collection sub-module is arranged at the front end of the collector. The second half-wave plate 16 and the third half-wave plate 19 are both 1560nm half-wave plates, and the second polarization beam splitting prism 17 and the third polarization beam splitting prism 20 are both 1560nm PBS. It should be noted that although the upper collection sub-module in the embodiment includes a DM mirror, the DM mirror is not necessarily included in the collection sub-module. Figure 2 The DM mirror is only used to concentrate the light path transmission and avoid a too large picture, so as to facilitate observation. It should be understood that the DM mirror is not necessarily included in the collection sub-module.

[0058] In a preferred embodiment, as shown in Figure 2 In order to match the polarization of the collected entangled photons with the superconducting nanowire single-photon detector (SNSPD) and improve the detection efficiency, the collection module further includes a second polarization controller 22 and a third polarization controller 23.

[0059] The output end of the first collector 18 is connected to the input end of the second polarization controller 22, and the output end of the second collector 21 is connected to the input end of the third polarization controller 23.

[0060] According to the actual measurement, the performance of the compact entangled source system of the embodiment is as follows:

[0061] 1) Collection efficiency: average 83.75%;

[0062] Table 1 Collection efficiency of the compact entangled source system

[0063] Pump light polarization Average number of photons per pulse Alice measurement side efficiency Bob measurement side efficiency V 0.014 84.143%（±0.476%） 83.454%（±0.499%） H 0.015 83.868%（±0.493%） 83.526%（±0.484%）

[0064] 2) Horizontal / vertical basis vector contrast: 99.475%, diagonal / anti-diagonal basis vector contrast: 97.63%, fidelity: 98.8%;

[0065] 3) Long-term stability of collection efficiency:

[0066] As shown in Figures 3 to 5 The embodiment collects the temperature change of the environment in which the compact entangled source system is located within a certain time period and counts the coincidence efficiency change of the system Alice and Bob measurement end within a certain time period. The certain time period is preferably 10000min, Figure 3 The temperature change of the environment in which the compact entangled source is located within a certain time period is shown, Figure 4 The Alice measurement end efficiency change of the compact entangled source within a certain time period is shown, Figure 5The efficiency change of the compact entanglement source at the Bob measurement end in a specific time period is shown. It can be seen that the collection efficiency of the compact entanglement source system can remain stable for a long time even if the ambient temperature of the compact entanglement source system changes over time.

[0067] In conclusion, the performance of the compact entanglement source system meets the requirements of device-independent quantum random number generation.

[0068] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. An optically-cured Sagnac loop, characterized by, include: The system includes a fixed base plate, collimator, filter, dichroic mirror, first polarizing beam splitter prism, first half-wave plate, first reflecting mirror, second reflecting mirror, periodically polarized potassium titanyl phosphate crystal, first spherical lens, second spherical lens, third spherical lens, and fourth spherical lens. The collimator, the filter, the dichroic mirror, the first polarizing beam splitter prism, the first half-wave plate, the first reflector, the second reflector, the periodically polarized potassium titanyl phosphate crystal, the first spherical lens, the second spherical lens, the third spherical lens, and the fourth spherical lens are all fixed to the fixed base plate using high-precision optical bonding technology. The dichroic mirror, the first polarizing beam splitter prism, the first half-wave plate, the first reflector, the periodically polarized potassium titanyl phosphate crystal, and the second reflector are arranged to form a Sagnac ring structure. The filter is disposed between the collimator and the dichroic mirror. The first entangled photon output by the Sagnac ring structure passes through the first spherical lens and the second spherical lens and reaches the first output end of the optically solidified Sagnac ring. The second entangled photon output by the Sagnac ring structure passes through the third spherical lens and the fourth spherical lens and reaches the second output end of the optically solidified Sagnac ring.

2. The optically-cured Sagnac loop of claim 1, wherein, In the Sagnac ring structure, the dichroic mirror and the first polarizing beam splitter are configured as follows: When the collimator emits light, the light passes through the filter and enters the light-transmitting surface of the dichroic mirror at a 45-degree angle. After passing through the dichroic mirror, the light enters the first polarizing beam splitter at a 45-degree angle to the interference film in the first polarizing beam splitter. The first polarizing beam splitter then splits the light into horizontally polarized light and vertically polarized light.

3. The optically-cured Sagnac loop of claim 2, wherein, In the Sagnac ring structure, the first half-wave plate, the first reflector, the second reflector, and the periodically polarized potassium titanium oxyphosphate crystal are configured as follows: The horizontally polarized light, after passing through the first half-wave plate, is reflected by the first mirror and enters one end of the periodically polarized potassium titanium phosphate crystal. The vertically polarized light, after being reflected by the second mirror, enters the other end of the periodically polarized potassium titanium phosphate crystal, and the light entering from both ends of the periodically polarized potassium titanium phosphate crystal is on the same straight line.

4. The optically-cured Sagnac loop of claim 2, wherein, The diameter of the beam waist of the collimator emitted by the collimator is 0.36-0.4 mm.

5. The optically-cured Sagnac loop of claim 1, wherein, The first spherical lens and the third spherical lens are plano-convex spherical mirrors, and the second spherical lens and the fourth spherical lens are plano-concave spherical mirrors.

6. A compact entanglement source, characterized in that, The device includes the optically cured Sagnac ring as described in any one of claims 1 to 5, and further includes a pump module and a collection module; The output of the pump module is connected to the input of the optically cured Sagnac ring, and the input of the optically cured Sagnac ring is connected to the collimator.

7. The compact entanglement source of claim 6, wherein, The pump module includes: a pump laser and a first polarization controller; The pump laser emits pump light to the input end of the first polarization controller, and the output end of the first polarization controller is connected to the output end of the pump module.

8. The compact entanglement source of claim 6 or 7, wherein, The collection module comprises a first collection sub-module and a second collection sub-module. The first collection sub-module comprises a second half-wave plate, a second polarization beam splitter prism, a first aspherical lens and a first collector. The first entangled photons output by the first output end of the optical solidification Sagnac ring pass through the second half-wave plate, the second polarization beam splitter prism and the first aspherical lens in sequence and then input the first collector. The second collection sub-module comprises a third half-wave plate, a third polarization beam splitter prism, a second aspherical lens and a second collector. The second entangled photons output by the second output end of the optical solidification Sagnac ring pass through the third half-wave plate, the third polarization beam splitter prism and the second aspherical lens in sequence and then input the second collector.

9. The compact entanglement source of claim 8, wherein, The collection module further comprises a second polarization controller and a third polarization controller. The output end of the first collector is connected to the input end of the second polarization controller, and the output end of the second collector is connected to the input end of the third polarization controller.

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