CN117192864A - Integrated single photon module for preparing quantum entangled photon pair - Google Patents

Abstract

The application provides an integrated single photon module for preparing quantum entangled photon pairs, comprising: the device comprises a pump laser, a dichroic mirror, a first half-wave plate, a second half-wave plate, a quarter-wave plate, a first polarization beam splitter, a nonlinear crystal and a module base; the pump laser comprises a laser diode and a laser driving module; the dichroic mirror, the first half wave plate, the second half wave plate and the quarter wave plate are sheet glass bodies comprising a coating surface layer, the first polarization beam splitter is a cube glass body comprising a coating surface layer, and the nonlinear crystal is a PPKTP crystal or a beta-barium metaborate crystal or a PPKTP waveguide carved on the crystal; the dichroic mirror, the first half-wave plate, the second half-wave plate, the quarter-wave plate and the first polarization beam splitter are fixed on the module base. The application can prepare the quantum entangled photon pair with high stability through an integrated single photon module.

Description

Integrated single photon module for preparing quantum entangled photon pair

Technical Field

The application relates to the technical field of quantum communication, in particular to an integrated single photon module for preparing quantum entangled photon pairs.

Background

High quality quantum entanglement sources have wide applications in the field of quantum information processing, such as quantum imaging, quantum precision measurement, quantum key distribution, quantum computation, information processing, and the like.

At present, a quantum entanglement source mainly adopts a nonlinear crystal to carry out spontaneous parametric down-Conversion (Spontaneous Parametric Down-Conversion, SPDC) technology to prepare photon pairs which are quantum entangled with each other. In the prior art, most quantum entanglement sources relate to specific pump lasers, pump sources, single photon detectors, a large number of wave plates (half wave plates, 1/4 wave plates and the like), optical filters (interference filters, long-pass filters and the like), reflectors, dichroic mirrors, beam splitters, polarization beam splitters, optical fiber coupling lenses, various lenses, coupling frames and the like. The optical components have large space, high cost and poor stability. All the devices also need to be fixed on an optical platform or an optical bread board to prevent the increase of coupling loss between various lens reflectors and coupling frames and between optical fibers caused by vibration.

Therefore, there is an urgent need to develop a modular, low cost, high stability quantum entanglement source.

Disclosure of Invention

In order to solve the problems, the application provides an integrated single-photon module for preparing quantum entangled photon pairs, which can prepare the quantum entangled photon pairs by using the integrated single-photon module with high integration level, low cost, simple structure and stable performance.

The application provides an integrated single photon module for preparing quantum entangled photon pairs, comprising: the device comprises a pump laser, a dichroic mirror, a first half-wave plate, a second half-wave plate, a quarter-wave plate, a first polarization beam splitter, a nonlinear crystal and a module base; the pump laser comprises a laser diode and a laser driving module; the dichroic mirror, the first half wave plate, the second half wave plate and the quarter wave plate are sheet glass bodies comprising a coating surface layer, the first polarization beam splitter is a cube glass body comprising a coating surface layer, and the nonlinear crystal is a PPKTP crystal or a beta-barium metaborate crystal or a PPKTP waveguide carved on the crystal; the dichroic mirror, the fourth half-wave plate, the first half-wave plate, the second half-wave plate and the first polarization beam splitter are fixed on the module base; the pump laser is used for generating pump light, the first half-wave plate, the quarter-wave plate, the dichroic mirror and the first polarization beam splitter are used for transmitting and controlling polarization components of the pump light, and the first polarization beam splitter, the nonlinear crystal and the second half-wave plate are used for controlling horizontal polarization components of the pump light to generate quantum entangled photon pairs.

Therefore, the functions of a large number of optical components required by the original quantum entanglement source are realized through the optical film, the optical film is packaged and fixed, and pump light is generated through the laser diode and the laser driving module, so that the volume of the integrated single photon module can be reduced, and the stability of preparing quantum entanglement photon pairs is improved.

In one possible implementation, the integrated single photon module comprises a laser processing module; the pump laser is connected with a laser processing module through an optical fiber, and the laser processing module is used for processing pump light and transmitting the pump light to the first half-wave plate.

In one possible implementation, the laser processing module includes a laser collimation device; the laser collimation device is fixed on the module base; processing and emitting pump light onto a first half-wave plate, comprising: the laser collimation device is used for collimating and emitting the pump light output by the pump laser into free space, and the pump light is made to be incident on the first half-wave plate from the horizontal direction.

In one possible implementation, the laser processing module includes a laser collimation device, a third half-wave plate, a second polarization beam splitter; the third half wave plate is a sheet glass body comprising a coated surface layer, and the second polarization beam splitter is a cube glass body comprising a coated surface layer; the laser collimation device, the third half-wave plate and the second polarization beam splitter are sequentially arranged along the light path and are respectively fixed on the module base; processing and emitting pump light onto a first half-wave plate, comprising: using a laser collimation device to collimate and emit the pump light output by the pump laser into a free space, and enabling the pump light to be incident on a third half wave plate from the horizontal direction; and respectively regulating the light intensity of the pump light by using a third half wave plate and a second polarization beam splitter to obtain first pump light, and enabling the first pump light to be incident on the first half wave plate from the horizontal direction.

In one possible implementation manner, the integrated single photon module further comprises a first long-wave pass filter, a second long-wave pass filter, a first optical fiber coupling device and a second optical fiber coupling device; the first long-wave pass filter and the second long-wave pass filter are sheet glass bodies comprising coating film surface layers, and the first long-wave pass filter, the second long-wave pass filter, the first optical fiber coupling device and the second optical fiber coupling device are fixed on the module base; the dichroic mirror, the first long-wave pass filter and the first optical fiber coupling device are sequentially arranged to form a first optical path, the first polarizing beam splitter, the second long-wave pass filter and the second optical fiber coupling device are sequentially arranged to form a second optical path, and the first optical path and the second optical path are respectively used for transmitting one single photon in the quantum entangled photon pair.

In one possible implementation, the first half-wave plate, the quarter-wave plate, the dichroic mirror, and the first polarizing beam splitter are disposed along the optical path in that order; the Sagnac ring is composed of at least a first polarization beam splitter, a nonlinear crystal and a second half-wave plate.

In one possible implementation, the integrated single photon module further comprises a third fiber coupling device, a first crystal coupling device, a fourth fiber coupling device, and a second crystal coupling device; the third optical fiber coupling device, the first crystal coupling device, the fourth optical fiber coupling device and the second crystal coupling device are fixed on the module base; the third optical fiber coupling device and the first crystal coupling device are used for realizing light transmission between the nonlinear crystal and the second half-wave plate, and the third optical fiber coupling device is connected with the first crystal coupling device through an optical fiber; the fourth optical fiber coupling device and the second crystal coupling device are used for realizing light transmission between the nonlinear crystal and the first polarization beam splitter, and the fourth optical fiber coupling device is connected with the second crystal coupling device through an optical fiber.

In one possible implementation, the integrated single photon module further comprises a first mirror, a second mirror; the first reflecting mirror and the second reflecting mirror are sheet glass bodies comprising film coating surface layers, and are fixed on the module base; the first reflecting mirror is used for reflecting the emergent light of the second half wave plate into the nonlinear crystal; the second mirror is used for reflecting the emergent light of the nonlinear crystal into the first polarization beam splitter.

In one possible implementation, the PPKTP crystal or the beta-barium metaborate crystal includes written optical waveguides or optical waveguides fabricated using chemical etching methods, respectively; the writing comprises writing by using a laser femtosecond technology, and the optical waveguide manufactured by a chemical etching method is an optical waveguide manufactured by using a chemical etching mode; the optical waveguide is used for guiding the transmission direction of light in the nonlinear crystal; the module base comprises a clamping groove, and the nonlinear crystal is fixed in the clamping groove.

In one possible implementation, the integrated single photon module includes an electrical input interface and an optical fiber output interface; the interfaces in the electric input interface are respectively used for carrying out laser control on the pump laser, carrying out temperature control on the nonlinear crystal, and the optical fiber output interface is used for outputting quantum entangled photon pairs; the integrated single photon module adopts airtight packaging technology.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a method of preparing quantum entangled photon pairs;

FIG. 2 is an integrated single photon module for preparing quantum entangled photon pairs provided by an embodiment of the present application;

FIG. 3 is a schematic diagram of a laser processing module integrated with a single photon module according to an embodiment of the present application;

fig. 4 is a schematic diagram of a sagnac loop of an integrated single photon module according to an embodiment of the present application;

fig. 5 is a schematic diagram of a sagnac loop of an integrated single photon module according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be described below with reference to the accompanying drawings.

In describing embodiments of the present application, words such as "exemplary," "such as" or "for example" are used to mean serving as examples, illustrations or explanations. Any embodiment or design described herein as "exemplary," "such as" or "for example" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "such as" or "for example," etc., is intended to present related concepts in a concrete fashion.

In the description of the embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, and indicates that three relationships may exist, for example, a and/or B may indicate: a alone, B alone, and both A and B. In addition, unless otherwise indicated, the term "plurality" means two or more. For example, a plurality of systems means two or more systems, and a plurality of screen terminals means two or more screen terminals.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating an indicated technical feature. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless expressly specified otherwise.

The existing spontaneous parametric down-conversion technology is mainly based on beta-barium metaborate (beta-BBO) crystals and periodically polarized potassium titanyl phosphate (PPKTP) crystals, and the nonlinear crystals are subjected to down-conversion by a pump laser to obtain quantum entangled photon pairs.

A schematic diagram of the preparation of quantum entangled photon pairs is shown in fig. 1. As shown in fig. 1, the pump light with 780nm emission wavelength of the pump LASER is polarized by a quarter wave plate QWP and a half wave plate HWP2, filtered by a filter Lens, split into horizontal and vertical polarization components by a dichroic mirror DM (dichroic mirror, DM) and a polarization beam splitter PBS (polarization beam splitter, PBS), and injected into a Sagnac loop composed of a nonlinear crystal PPKTP and a half wave plate HWP 1. The horizontal and vertical polarization components of the pump light are respectively transmitted along the anticlockwise direction and the clockwise direction of the ring, respectively enter from two ends of the nonlinear crystal, generate parametric light which is transmitted in opposite directions, respectively transmit along the anticlockwise direction and the clockwise direction, return to the PBS, form a combined beam and generate entanglement, filter entangled photon pairs through a long-pass filter LP, collect the entangled photon pairs through a single-mode fiber SMF, and enter into a single-photon detector APDs. In the Sagnac ring, the PPKTP crystal TYPE 2 is utilized to realize 780nm laser parameter down-conversion, and 1560nm entangled photon pairs are generated. The scope of protection is not limited to 780nm and 1560nm optical wavelength conversion.

As can be seen from fig. 1, besides the specific pump laser, pump source, single photon detector, and a large number of wave plates (half wave plate, 1/4 wave plate, etc.), optical filters (interference filter, long pass filter, etc.), reflectors, dichroic mirrors, beam splitters, polarization beam splitters, it is necessary to design a lens with a proper focal length to focus the pump light to a certain extent, so as to obtain higher nonlinear conversion efficiency, and control the phase matching condition by temperature. The pump light needs to be blocked and filtered at the emission port of the nonlinear crystal PPKTP, collimation is needed to collect entangled photons and the entangled photons are coupled into the optical fiber, and finally performance verification can be performed through a single photon detector. All the devices also need to be fixed on an optical platform or an optical bread board to prevent the increase of coupling loss between various lens reflectors and coupling frames and between optical fibers caused by vibration.

It is not difficult to find that the quantum entanglement source shown in fig. 1 has mainly the following problems:

first, a large number of optical components are required, which are generally expensive and oversized, and are not suitable for use in large-scale engineered products.

Second, existing quantum entanglement source systems typically require additional laser driving equipment and cannot be modularly miniaturized.

In view of this, the embodiment of the application provides an integrated single photon module for preparing quantum entangled photon pairs, which realizes the functions of a large number of optical components required by the original quantum entangled source through an optical film, encapsulates and fixes the optical film, and then generates pumping light through a laser diode and a laser driving module, so that the volume of the integrated single photon module can be reduced, and the stability for preparing quantum entangled photon pairs can be improved.

An integrated single photon module for preparing quantum entangled photon pairs provided in the examples of application will be described in detail based on the above analysis.

An integrated single photon module for preparing quantum entangled photon pairs provided by an embodiment of the present application is shown in fig. 2. As shown in fig. 2, the integrated single photon module includes: the laser processing module comprises a pump laser 1, a laser processing module 2, a first half-wave plate 3, a quarter-wave plate 4, a dichroic mirror 5, a first polarizing beam splitter 6, a nonlinear crystal 7, a second half-wave plate 8 and a module base.

As shown in fig. 2, a pump laser 1, a laser processing module 2, a first half-wave plate 3, a quarter-wave plate 4, a dichroic mirror 5, and a first polarizing beam splitter 6 are disposed in this order along an optical path.

The integrated single photon module further comprises a first long-wave filter 9, a second long-wave filter 10, a first optical fiber coupling device 11 and a second optical fiber coupling device 12.

The dichroic mirror 5, the first long-wave filter 9 and the first optical fiber coupling device 11 are sequentially arranged to form a first optical path, the first polarizing beam splitter 6, the second long-wave filter 10 and the second optical fiber coupling device 12 are sequentially arranged to form a second optical path, and the first optical path and the second optical path are respectively used for transmitting one single photon in the quantum entangled photon pair.

The pump laser 1 is used for generating pump light, and the laser processing module 2, the first half-wave plate 3, the quarter-wave plate 4, the dichroic mirror 5 and the first polarization beam splitter 6 are used for transmitting and controlling the polarization component of the pump light. The pump laser 1 is connected with a laser processing module 2 through an optical fiber, and the laser processing module 2 is used for processing pump light and emitting the pump light onto a first half-wave plate 3.

In one implementation, as shown in the schematic diagram of the laser processing module structure of the integrated single photon module in fig. 3 (a), the laser processing module 2 includes a laser collimator device 13, and the laser collimator device 13 is fixed on the module base. The laser collimation device 13 may be used to collimate and emit the pump light output from the pump laser 1 into free space and make the pump light incident on the first half-wave plate 3 from the horizontal direction.

In another implementation, as shown in the schematic structure of the laser processing module integrated with the single photon module in fig. 3 (b), the laser processing module 2 includes a laser collimation device 13, a third half-wave plate 14, and a second polarization beam splitter 15. Wherein the laser collimation device 13, the third half-wave plate 14 and the second polarization beam splitter 15 are sequentially arranged along the optical path.

First, the pump light output from the pump laser may be collimated and emitted into free space using the laser collimating device 13, and made incident on the third half-wave plate 14 from the horizontal direction. And then the third half wave plate 14 and the second polarization beam splitter 15 are used for sequentially adjusting the light intensity of the pump light to obtain first pump light. Finally, the first pump light is made incident on the first half-wave plate 3 from the horizontal direction.

The integrated single photon module further comprises, illustratively, a Sagnac loop consisting of at least a first polarizing beam splitter 6, a nonlinear crystal 7, and a second half-wave plate 8. In the Sagnac loop, quantum entangled photon pairs are generated from the horizontally polarized component of the pump light.

In one implementation, the Sagnac loop is formed based on a first polarizing beam splitter 6, a nonlinear crystal 7, and a second half-wave plate 8, in combination with a fiber coupling device and a crystal coupling device.

In another implementation, the Sagnac loop can also be formed by combining two reflectors based on the first polarizing beam splitter 6, the nonlinear crystal 7 and the second half-wave plate 8.

The nonlinear crystal 7 may be a PPKTP crystal or a beta-barium metaborate crystal or a PPKTP waveguide inscribed on the crystal. Down-converting entangled single photon pairs for creating entanglement in a Sagnac loop. The principle of generating entangled single photon pairs using nonlinear crystals is shown in the Sagnac loop of fig. 1 and will not be described again.

Illustratively, the PPKTP crystal or the beta-barium metaborate crystal includes a written optical waveguide or an optical waveguide fabricated using a chemical etching process, respectively. Writing includes writing using a laser femtosecond technique, and the optical waveguide manufactured by the chemical etching method is an optical waveguide manufactured by a chemical etching method. The optical waveguide is used to guide the transmission direction of light in the nonlinear crystal 7.

In one implementation, a clamping groove can be formed in the module base, and nonlinear crystals 7 of different types are embedded in the clamping groove to support more application scenes, so that the nonlinear crystals 7 can be replaced conveniently in this way. In another implementation, the nonlinear crystal 7 can also be directly fixed on the module base, in which way the optical transmission losses can be reduced.

Fig. 4 shows a sagnac loop schematic diagram of an integrated single photon module according to an embodiment of the present application. As shown in fig. 4, based on the integrated single photon module shown in fig. 2, the Sagnac loop of the integrated single photon module is composed of a first polarization beam splitter 6, a nonlinear crystal 7, a second half-wave plate 8, a third optical fiber coupling device 16, a first crystal coupling device 17, a fourth optical fiber coupling device 18, and a second crystal coupling device 19.

Specifically, the first polarization beam splitter 6, the fourth optical fiber coupling device 18, the second crystal coupling device 19, the nonlinear crystal 7, the first crystal coupling device 17, the third optical fiber coupling device 16 and the second half-wave plate 8 are connected end to end.

The third optical fiber coupling device 16 and the first crystal coupling device 17 are used for realizing light transmission between the nonlinear crystal 7 and the second half-wave plate 8, and the third optical fiber coupling device 16 and the first crystal coupling device 17 are connected through optical fibers;

the fourth optical fiber coupling device 18 and the second crystal coupling device 19 are used for realizing light transmission between the nonlinear crystal 7 and the first polarization beam splitter 6, and the fourth optical fiber coupling device 18 and the second crystal coupling device 19 are connected through optical fibers.

The function of the optical fiber coupling device in fig. 2 and 3 is to couple light into the optical fiber from free space or to collimate the light out of the optical fiber into free space for transmission, and the function of the crystal coupler in fig. 3 is to direct light to certain optical components to couple light from the optical fiber to the crystal or from the crystal to the optical fiber for transmission.

Fig. 5 shows a sagnac loop schematic diagram of an integrated single photon module according to an embodiment of the present application. As shown in fig. 5, the Sagnac loop of the integrated single photon module based on the integrated single photon module shown in fig. 2 is composed of a first polarization beam splitter 6, a nonlinear crystal 7, a second half-wave plate 8, a first reflecting mirror 20, and a second reflecting mirror 21.

Specifically, the first polarizing beam splitter 6, the second reflecting mirror 21, the nonlinear crystal 7, the first reflecting mirror 20, and the second half-wave plate 8 are connected end to end. Wherein the first reflecting mirror 20 is used for reflecting the emergent light of the second half-wave plate 8 into the nonlinear crystal; the second reflecting mirror 21 is used for reflecting the emergent light of the nonlinear crystal into the first polarization beam splitter.

In the optical component shown in fig. 2-4, the first half-wave plate 3, the second half-wave plate 8, the quarter-wave plate 4, the dichroic mirror 5, the first long-wave pass filter 9, the second long-wave pass filter 10, the third half-wave plate 14, the first reflecting mirror 20 and the second reflecting mirror 21 may be a sheet glass body including a coating surface layer, and the surfaces of the sheet glass bodies with different sizes are coated to realize the functions of the corresponding optical component. For example, the half wave plate and the quarter wave plate are used for rotating polarized light at different angles, and the long wave pass filter is used for selecting polarized light of a required radiation wave band. Dichroic mirrors are used to separate specific spectra from polarized light to change the direction of the optical path of a portion of the spectrum. The mirror is used to change the propagation direction of polarized light.

The first polarizing beam splitter 6 and the second polarizing beam splitter 15 may be a cubic glass body including a coated surface layer for dividing incident unpolarized light into two linearly polarized light beams having perpendicular polarization. Wherein the horizontally polarized light passes completely and the vertically polarized light is reflected, the exit direction being at an angle of 90 degrees to the horizontally polarized light.

The volume of the optical diaphragm or the polarizing beam splitter glass cube, the performance parameters of the plating film and the selection of glass materials are all required to be combined with the specific requirements of the integrated single photon module on wavelength, bandwidth, reflectivity, refractive index and polarization characteristics to carry out specific type selection.

The pump laser 1 is a pump light emission source composed of a laser diode and a laser driving module, and is used for generating and emitting pump single photons. The laser driving module can tailor the function of the laser driving module according to the parameters such as the power of the laser diode, the laser band value and the like. For example, a large pump laser can support the emission of a larger range of laser beams, and the corresponding laser driving module requires more components to achieve support for these ranges. The laser band emitted by the laser diode is usually fixed, so that the corresponding components of the laser driving module for adjusting the laser band can be cut to meet the miniaturization requirement, and only the laser driving function necessary for the specific laser band is reserved.

The devices shown in fig. 2-4 are fixed on the module base at a certain angle according to the propagation direction of the light path, and the fixing mode can be glue packaging or screw fixing. The module base can be a kovar alloy or other metal base plate.

The integrated single photon module shown in fig. 2 comprises, for example, 5 electrical interfaces, two of which (ld+, LD-) are used for controlling the laser driving module, two of which (tec+, TEC-) are used for controlling the temperature of the nonlinear crystal 7, and one common ground interface of the integrated single photon module is used for connecting the common ground of the optical transmission system, shielding the interference of static electricity with the optical transmission path.

The integrated single photon module comprises 2 optical output interfaces for entangled pairs of generated single photons to be output through an optical fiber.

Specifically, a control signal (LD) of laser and a temperature control signal (TEC) of nonlinear crystal are connected to the integrated single photon module shell through an aluminum nitride gold wire, a light output interface is connected to a single photon detector through Fc, and finally the whole integrated single photon module realizes airtight packaging through a parallel seam welding process.

In addition, the optical waveguide is written in the nonlinear crystal and used for adjusting the transmission direction of light in the nonlinear crystal, so that the second harmonic conversion efficiency of the nonlinear crystal is increased, and the efficiency of preparing quantum entangled photon pairs is improved. The writing mode includes writing by using laser femtosecond technology, writing by using chemical etching mode, and the like. For example, in order to improve the coupling efficiency of the PPKTP crystal, reduce the light source loss, a type II waveguide of 10mm can be directly written in the PPKTP crystal cut by c through focused femtosecond laser pulses, the angle of single photon incidence to the PPKTP crystal is adjusted, single-mode transmission in the waveguide is realized, and the conversion efficiency of the second harmonic is improved. In addition, temperature control of the PPKTP crystal is realized through modularized TEC temperature control, so that the stability of the whole single photon module can be ensured.

In one embodiment, the entire module includes 5 electrical input interfaces and 2 fiber optic output interfaces. Wherein, 2 electric input interfaces are used for the power control of laser diode, 2 electric input interfaces are used for the temperature control of nonlinear crystal, 1 electric input interface is used for switch on GND, and 2 optical fiber output interfaces output the quantum entangled photon pair that can prepare. All optical films and crystals can be fixed on kovar alloy or other metal substrates through glue or screws, a laser control signal (LD) and a PPKTP temperature control signal (TEC) are connected to a module shell through aluminum nitride gold wires, an optical fiber interface is connected to a single photon detector through FC, and the components in the whole integrated single photon module are hermetically packaged through a parallel seam welding process.

In summary, since the nonlinear crystal-based high-quality single photon entanglement source is highly integrated, the nonlinear crystal-based high-quality single photon entanglement source is small in size and convenient to move and integrate in other devices. The output quantum entangled photon pair, i.e. signal and idler photons are output through the optical fiber in two paths. In addition, because the semiconductor laser is used as the pumping of the light source, the starting-up light emission, calibration and maintenance are avoided, the internal light path is packaged in an integrated form of a crystal and a waveguide, the connection between the internal light path and the waveguide is more reliable and compact, the coupling interference between the internal light path and the waveguide can be reduced, and the accuracy of preparing quantum entangled photon pairs is further improved.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, produces a flow or function in accordance with embodiments of the present application, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions may be stored in or transmitted from one computer-readable storage medium to another, for example, by wired (e.g., coaxial cable, optical fiber, digital Subscriber Line (DSL)), or wireless (e.g., infrared, wireless, microwave, etc.). The computer readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. that contains an integration of one or more available media. The usable medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a Solid State Disk (SSD)), or the like.

It will be appreciated that the various numerical numbers referred to in the embodiments of the present application are merely for ease of description and are not intended to limit the scope of the embodiments of the present application. It should be understood that, in the embodiment of the present application, the sequence number of each process does not mean the sequence of execution, and the execution sequence of each process should be determined by the function and the internal logic of each process, and should not limit the implementation process of the embodiment of the present application.

The foregoing embodiments have been provided for the purpose of illustrating the general principles of the present application in further detail, and are not to be construed as limiting the scope of the application, but are merely intended to cover any modifications, equivalents, improvements, etc. based on the teachings of the application.

Claims (10)

1. An integrated single photon module for preparing quantum entangled photon pairs, the integrated single photon module comprising: the device comprises a pump laser, a dichroic mirror, a first half-wave plate, a second half-wave plate, a quarter-wave plate, a first polarization beam splitter, a nonlinear crystal and a module base;

the pump laser comprises a laser diode and a laser driving module; the dichroic mirror, the first half wave plate, the second half wave plate and the quarter wave plate are sheet glass bodies comprising a coating surface layer, the first polarization beam splitter is a cube glass body comprising a coating surface layer, and the nonlinear crystal is PPKTP crystal or beta-barium metaborate crystal or PPKTP waveguide carved on the crystal;

the dichroic mirror, the first half-wave plate, the second half-wave plate, the quarter-wave plate and the first polarization beam splitter are fixed on the module base;

the pump laser is used for generating pump light, the first half-wave plate, the quarter-wave plate, the dichroic mirror and the first polarization beam splitter are used for transmitting and controlling polarization components of the pump light, and the first polarization beam splitter, the nonlinear crystal and the second half-wave plate are used for controlling horizontal polarization components of the pump light to generate quantum entangled photon pairs.

2. The module of claim 1, wherein the integrated single photon module comprises a laser processing module;

the pump laser is connected with the laser processing module through an optical fiber, and the laser processing module is used for processing the pump light and transmitting the pump light to the first half-wave plate.

3. The module of claim 2, wherein the laser processing module comprises a laser collimation device; the laser collimation device is fixed on the module base;

the processing and emitting the pump light onto the first half-wave plate includes:

and using the laser collimation device to collimate and emit the pump light output by the pump laser into free space, and enabling the pump light to be incident on the first half-wave plate from the horizontal direction.

4. The module of claim 2, wherein the laser processing module comprises a laser collimation device, a third half-wave plate, a second polarizing beam splitter; the third half-wave plate is a sheet glass body comprising a coated surface layer, and the second polarization beam splitter is a cube glass body comprising a coated surface layer;

the laser collimation device, the third half-wave plate and the second polarization beam splitter are sequentially arranged along the light path and are respectively fixed on the module base;

the processing and emitting the pump light onto the first half-wave plate includes:

using the laser collimation device to collimate and emit the pump light output by the pump laser into a free space, and enabling the pump light to be incident on the third half wave plate from the horizontal direction;

and sequentially adjusting the light intensity of the pump light by using the third half wave plate and the second polarization beam splitter to obtain first pump light, and enabling the first pump light to be incident on the first half wave plate from the horizontal direction.

5. The module of claim 1, wherein the integrated single photon module further comprises a first long-wave pass filter, a second long-wave pass filter, a first fiber coupling device, a second fiber coupling device;

the first long-wave pass filter and the second long-wave pass filter are sheet glass bodies comprising coating surface layers, and the first long-wave pass filter, the second long-wave pass filter, the first optical fiber coupling device and the second optical fiber coupling device are fixed on the module base; wherein,

the dichroic mirror, the first long-wave pass filter and the first optical fiber coupling device are sequentially arranged to form a first optical path, the first polarizing beam splitter, the second long-wave pass filter and the second optical fiber coupling device are sequentially arranged to form a second optical path, and the first optical path and the second optical path are respectively used for transmitting one single photon in the quantum entangled photon pair.

6. The module of claim 1, wherein the first half-wave plate, quarter-wave plate, dichroic mirror, and first polarizing beam splitter are disposed along the optical path in sequence; and the Sagnac ring is formed by at least the first polarization beam splitter, the nonlinear crystal and the second half-wave plate.

7. The module of claim 1, wherein the integrated single photon module further comprises a third fiber coupling device, a first crystal coupling device, a fourth fiber coupling device, a second crystal coupling device; the third optical fiber coupling device, the first crystal coupling device, the fourth optical fiber coupling device and the second crystal coupling device are fixed on the module base; wherein,

the third optical fiber coupling device and the first crystal coupling device are used for realizing optical transmission between the nonlinear crystal and the second half-wave plate, and the third optical fiber coupling device and the first crystal coupling device are connected through optical fibers;

the fourth optical fiber coupling device and the second crystal coupling device are used for realizing light transmission between the nonlinear crystal and the first polarization beam splitter, and the fourth optical fiber coupling device and the second crystal coupling device are connected through optical fibers.

8. The module of claim 1, wherein the integrated single photon module further comprises a first mirror, a second mirror; the first reflecting mirror and the second reflecting mirror are sheet glass bodies comprising film coating surface layers, and are fixed on the module base; wherein,

the first reflecting mirror is used for reflecting the emergent light of the second half-wave plate into the nonlinear crystal;

the second reflecting mirror is used for reflecting outgoing light of the nonlinear crystal into the first polarization beam splitter.

9. The module of claim 1, wherein the PPKTP crystal or the beta-barium metaborate crystal comprises a written optical waveguide or an optical waveguide fabricated using a chemical etching process, respectively; the writing comprises writing by using a laser femtosecond technology, and the optical waveguide manufactured by the chemical etching method is an optical waveguide manufactured by using a chemical etching mode; the optical waveguide is used for guiding the transmission direction of light in the nonlinear crystal;

the module base comprises a clamping groove, and the nonlinear crystal is fixed in the clamping groove.

10. The module of claim 1, wherein the integrated single photon module comprises an electrical input interface and an optical fiber output interface;

the interfaces in the electric input interface are respectively used for controlling the laser of the pump laser and controlling the temperature of the nonlinear crystal, and the optical fiber output interface is used for outputting the quantum entangled photon pair:

the integrated single photon module adopts an airtight packaging process.