Photon hyper-entangled state analysis device

Abstract

The invention discloses a photon hyper-entangled state analysis device, and relates to the technical field of quantum information processing, and the photon hyper-entangled state analysis device comprises a hyper-entangled state generation optical path, a signal-idler frequency photon separation optical path, an energy-time degree-of-freedom analysis optical path, and a polarization degree-of-freedom analysis optical path. Pump light generates a signal-idler frequency photon pair in the hyper-entangled state generation light path, then the signal-idler frequency photon pair is separated into signal photons and idler frequency photons through the signal-idler frequency photon separation light path, then energy-time freedom degree analysis is carried out through the energy-time freedom degree analysis light path, and finally polarization freedom degree analysis is carried out through the polarization freedom degree analysis light path. The hyper-entangled state analysis device provided by the invention can stably and synchronously realize energy-time and polarization degree-of-freedom joint analysis on the same chip based on an integrated optical platform, fundamentally solves the key problems of poor phase stability and complex control of a multi-degree-of-freedom analysis system, and realizes improvement of analysis efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantum information processing, and particularly relates to a photonic super-entangled state analysis device. BACKGROUND

[0002] At present, quantum entanglement is an important resource in the field of quantum information, and has been widely applied in the technical fields of quantum communication, quantum computing, quantum measurement and the like. Due to the advantages of easy preparation, easy control and long coherence time of photons, entangled photon pairs are favored in the quantum field, and photon entangled states based on different degrees of freedom are proposed one after another, including polarization, energy-time, time slice, frequency, angular momentum and the like. On a single degree of freedom, entanglement can only be realized in a single photon to encode a quantum bit, in order to improve the quantum information carried by a single photon, super-entangled states can be prepared to encode photons in multiple degrees of freedom in parallel, thereby significantly improving the quantum information capacity. However, the existing super-entangled state preparation and analysis means often need a large number of discrete optical devices to build a system, which has high cost, poor scalability and stability; based on an integrated optical platform to prepare and analyze super-entangled states can significantly improve the integration, stability and scalability of super-entangled states, and is easy to realize large-scale production.

[0003] The analysis of super-entangled states usually needs to prove the entanglement characteristics in each degree of freedom through quantum interference, which requires that the analysis optical path must maintain extremely high phase stability. Based on the existing technology, the energy-time degree of freedom is analyzed by a fiber interferometer, and the polarization is analyzed by a spatial optical path, so temperature fluctuations, vibration, air flow and the like will affect the two independent systems in different ways, causing phase drift. To make them work stably at the same time requires a complex control system, which is difficult to realize. SUMMARY

[0004] The present application provides a photonic super-entangled state analysis device, which can solve the problem of simultaneously analyzing two degrees of freedom in one device.

[0005] The present application provides a photonic super-entangled state analysis device, which comprises: a super-entangled state generation optical path, one side of which is provided with a pump light input end, and the other side is provided with a signal-idler photon pair output end; the pump light enters the super-entangled state generation optical path through the pump light input end to generate a signal-idler photon pair; a signal-idler photon separation optical path, which is provided with an input end and an output end, and the input end is connected with the signal-idler photon pair output end of the super-entangled state generation optical path; the signal-idler photon pair is separated into a signal photon and an idler photon through the signal-idler photon separation optical path; an energy-time degree of freedom resolving optical path, which is provided with an input end and an output end, the input end of which is connected with the output end of the hyper-entangled state generating optical path; the signal photons and idler photons after separation are subjected to energy-time degree of freedom resolving through the energy-time degree of freedom resolving optical path; a polarization degree of freedom resolving optical path, which is provided with an input end, the input end of which is connected with the output end of the energy-time degree of freedom resolving optical path, the signal photons and idler photons after energy-time degree of freedom resolving are subjected to polarization degree of freedom resolving through the polarization degree of freedom resolving optical path.

[0006] In an embodiment, the hyper-entangled state generating optical path comprises: a polarization rotation beam splitter, which is provided with an input end and an output end, the input end of which is connected with the input end of the pump light of the hyper-entangled state generating optical path, the polarization rotation beam splitter being used for rotating and separating the pump light into clockwise light field and counterclockwise light field; a micro ring, which is provided with an input end and an output end, the input end of which is connected with the output end of the polarization rotation beam splitter, the output end of which is connected with the output end of the signal-idler photon pair of the hyper-entangled state generating optical path, the micro ring being used for exciting nonlinear effect of the separated clockwise light field and counterclockwise light field to generate signal-idler photon pair.

[0007] In an embodiment, the hyper-entangled state generating optical path further comprises: a first thermo-optic phase shifter, which is arranged between the polarization rotation beam splitter and the micro ring, the first thermo-optic phase shifter being used for changing the phase of the clockwise light field; a first photodetector, which is connected in parallel with the first thermo-optic phase shifter, and is arranged between the polarization rotation beam splitter and the micro ring, the first photodetector being used for monitoring the intensity of the light field in counterclockwise direction.

[0008] In an embodiment, the signal-idler photon separation optical path comprises: two first unequal arm Mach-Zehnder interferometers, the input ends of which are connected with the output end of the signal-idler photon pair of the hyper-entangled state generating optical path, the output ends of which are connected with the input end of the energy-time degree of freedom resolving optical path.

[0009] In an embodiment, the first unequal arm Mach-Zehnder interferometer comprises: one long arm waveguide and one short arm waveguide; one second thermo-optic phase shifter, which is arranged on the one long arm waveguide or the one short arm waveguide; or two second thermo-optic phase shifters, which are respectively arranged on the one long arm waveguide and the one short arm waveguide; a first multimode interferometer, which is a 1x2 multimode interferometer, one input end of which is connected with the output end of the signal-idler photon pair of the hyper-entangled state generating optical path, two output ends of which are respectively connected with one end of the long arm waveguide and the short arm waveguide; a second multimode interferometer, which is a 2x2 multimode interferometer, has two input ends connected to the other ends of the long arm waveguide and the short arm waveguide respectively, and has two output ends connected to the input ends of the polarization degree of freedom resolved optical path respectively.

[0010] In an embodiment, the energy-time degree of freedom resolved optical path 3 comprises: four second unequal arm Mach-Zehnder interferometers, each of which comprises a long arm waveguide, a short arm waveguide, a third multimode interferometer, a fourth multimode interferometer, an input port and two output ports, the input port is connected to the signal-idler photonic separation optical path, the third multimode interferometer is a 1x2 multimode interferometer, which is arranged between the input port and the long arm waveguide and the short arm waveguide, and the fourth multimode interferometer is a 2x2 multimode interferometer, which is arranged between the long arm waveguide, the short arm waveguide and the two output ports; four optical delay line waveguides, each of which is arranged on the long arm waveguide of the second unequal arm Mach-Zehnder interferometer; a plurality of second photodetectors, each of which is arranged at one output port of each second unequal arm Mach-Zehnder interferometer; the other output port of the second unequal arm Mach-Zehnder interferometer is connected to the input end of the polarization degree of freedom resolved optical path.

[0011] In an embodiment, the second unequal arm Mach-Zehnder interferometer comprises: a third thermo-optic phase shifter arranged on the long arm waveguide or the short arm waveguide; or two third thermo-optic phase shifters arranged on the long arm waveguide and the short arm waveguide respectively.

[0012] In an embodiment, the polarization degree of freedom resolved optical path comprises: two equal arm Mach-Zehnder interferometers, each of which is provided with two input ports; two fourth thermo-optic phase shifters, each of which is arranged at one input port of each equal arm Mach-Zehnder interferometer, and the input port is connected to the other output port of the two second unequal arm Mach-Zehnder interferometers in the energy-time degree of freedom resolved optical path.

[0013] In an embodiment, the equal arm Mach-Zehnder interferometer further comprises: two equal length waveguides; a fifth multimode interferometer, which is a 2x2 multimode interferometer, is arranged between the input ports of the equal arm Mach-Zehnder interferometer and the two equal length waveguides; A sixth multimode interferometer, which is a 2x2 multimode interferometer, is arranged between the output port of the Mach-Zehnder interferometer and two waveguides of equal length; One fifth thermo-optic phase shifter is arranged on the waveguide; or two fifth thermo-optic phase shifters are arranged on the two waveguides, respectively.

[0014] In an embodiment, The other input ports of the two Mach-Zehnder interferometers are connected to the other output ports of the two second Mach-Zehnder interferometers with different lengths in the energy-time degree of freedom analysis optical path, respectively, after being crossed.

[0015] The photon super entangled state analysis device comprises a super entangled state generation optical path, one side of which is provided with a pump light input end, and the other side is provided with a signal-idler photon pair output end; a signal-idler photon separation optical path, which is provided with an input end and an output end, and the input end is connected to the signal-idler photon pair output end of the super entangled state generation optical path; the signal-idler photon pair is separated into signal photons and idler photons through the signal-idler photon separation optical path; an energy-time degree of freedom analysis optical path, which is provided with an input end and an output end, and the input end is connected to the output end of the super entangled state generation optical path; the separated signal photons and idler photons are subjected to energy-time degree of freedom analysis through the energy-time degree of freedom analysis optical path; a polarization degree of freedom analysis optical path, which is provided with an input end, and the input end is connected to the output end of the energy-time degree of freedom analysis optical path, and the signal photons and idler photons subjected to energy-time degree of freedom analysis are subjected to polarization degree of freedom analysis through the polarization degree of freedom analysis optical path. The present application provides a super entangled state analysis device based on integrated optics platform, which can stably and synchronously realize joint analysis of energy-time and polarization degrees of freedom on the same chip, and fundamentally solves the key problems of poor phase stability and complex control of multi-degree-of-freedom analysis system, and realizes the improvement of analysis efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0017] Figure 1 It is a first structure schematic diagram of the photon super entangled state analysis device of the embodiment of the present application. Figure 2 It is a second structure schematic diagram of the photon super entangled state analysis device of the embodiment of the present application.

[0018] In the figure: 1, super-entangled state generation light path; 2, signal-idler photon separation light path; 3, energy-time degree of freedom analysis light path; 4, polarization degree of freedom analysis light path; 11, polarization rotation beam splitter; 12, micro ring; 13, first thermo-optic phase shifter; 14, first photodetector; 21, first unequal arm Mach-Zehnder interferometer; 22, second thermo-optic phase shifter; 31, optical delay line waveguide; 32, second unequal arm Mach-Zehnder interferometer; 33, second photodetector; 34, third thermo-optic phase shifter; 41, fourth thermo-optic phase shifter; 42, equal arm Mach-Zehnder interferometer; 43, fifth thermo-optic phase shifter; 51, first multimode interferometer; 52, second multimode interferometer; 53, third multimode interferometer; 54, fourth multimode interferometer; 55, fifth multimode interferometer; 56, sixth multimode interferometer. DETAILED DESCRIPTION

[0019] In order to make the personnel in the technical field better understand the present application scheme, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0020] As shown in Figure 1 , 2 , the present application discloses a kind of photonic super-entangled state analysis device, it is characterized in that, including: super-entangled state generation light path 1, one side is equipped with pump light input end, the other side is equipped with signal-idler photon pair output end, pump light enters super-entangled state generation light path 1 in the pump light input end, generates signal-idler photon pair;Signal-idler photon separation light path 2 is equipped with input end and output end, its input end is connected with the signal-idler photon pair output end of super-entangled state generation light path, and the signal-idler photon pair is separated into signal photon and idler photon by the signal-idler photon separation light path 2;Energy-time degree of freedom analysis light path 3 is equipped with input end and output end, its input end is connected with the output end of super-entangled state generation light path;After separation, signal photon and idler photon are carried out energy-time degree of freedom analysis by energy-time degree of freedom analysis light path 3;Polarization degree of freedom analysis light path 4 is equipped with input end, its input end is connected with the output end of energy-time degree of freedom analysis light path, and signal photon and idler photon after energy-time degree of freedom analysis are carried out polarization degree of freedom analysis by polarization degree of freedom analysis light path 4.

[0021] For the analysis of entangled states, the prior art generally uses discrete devices to build different analysis optical paths to analyze different degrees of freedom respectively. The analysis optical path generally needs to be realized by quantum interference, which is very sensitive to phase. For the analysis systems of energy-time degrees of freedom and polarization degrees of freedom, external influencing factors such as temperature, airflow and vibration will cause phase drift of the two analysis systems at the same time, and a complex phase stabilization system is required to realize the simultaneous analysis of the two degrees of freedom.

[0022] The present application integrates the energy-time degree of freedom analysis optical path and the polarization degree of freedom analysis optical path into the same photonic super-entangled state analysis device through the integrated optical platform, and can stably and synchronously realize the joint analysis of energy-time and polarization degrees of freedom on the same chip, thereby fundamentally solving the key problems of poor phase stability and complex control of multi-degree-of-freedom analysis systems and realizing the improvement of analysis efficiency.

[0023] As shown in Figure 1 In an embodiment, the super-entangled state generation optical path comprises: a polarization rotation beam splitter 11 provided with an input end and an output end, the input end of which is connected with the pump light input end of the super-entangled state generation optical path 1, and the polarization rotation beam splitter 11 is used to rotate and separate the pump light into clockwise light field and counterclockwise light field; a micro ring 12 provided with an input end and an output end, the input end of which is connected with the output end of the polarization rotation beam splitter 11, and the output end is connected with the signal-idler photon pair output end of the super-entangled state generation optical path 1, and the micro ring 12 is used to excite the nonlinear effect of the separated clockwise light field and counterclockwise light field to generate signal-idler photon pairs.

[0024] As shown in Figure 1 The super-entangled state generation optical path 1 further comprises: a first thermo-optic phase shifter 13 arranged between the polarization rotation beam splitter 11 and the micro ring 12, the first thermo-optic phase shifter 13 is used to change the phase of the clockwise light field; a first photodetector 14 connected in parallel with the first thermo-optic phase shifter 13 and arranged between the polarization rotation beam splitter 11 and the micro ring 12, the first photodetector 14 is used to monitor the intensity of the counterclockwise light field.

[0025] The pump light is injected into the super-entangled state generation optical path 1, and the polarization rotation beam splitter 11 is used to separate the TE mode and TM mode of the pump light field, and rotate the TM mode into a new TE mode, so as to separate the two polarization components of the light field into two paths. The first photodetector 14 in the super-entangled state generation optical path 1 is used to monitor the intensity of the counterclockwise light field. The first thermo-optic phase shifter 13 in the super-entangled state generation optical path 1 is used to change the phase of the clockwise light field. The light field entering the micro ring 12 can be expressed as:

[0026] wherein and represent clockwise and anticlockwise optical fields respectively, and represent optical field intensity coefficients respectively, and satisfy , represents and phase difference between and. By controlling the polarization state of the pump light, the clockwise and anticlockwise optical field intensities entering the microring 12 can be made equal, that is:

[0027] The optical field enters the microring 12, and the spontaneous four-wave mixing effect is excited in the microring 12 to generate a signal-idler photon pair, marked with subscripts s and i respectively. The wavelengths of the signal light, idler light and pump light satisfy . For ease of understanding, the signal-idler photon pair excited by the clockwise optical field is denoted as , which enters the first multimode interferometer 51 on the upper right of the super entangled state generation optical path 1; the signal-idler photon pair excited by the anticlockwise optical field is denoted as , which enters the first multimode interferometer 51 on the lower right of the super entangled state generation optical path 1.

[0028] The present application can excite the pump light to generate signal-idler photon pairs by the super entangled state generation optical path.

[0029] As shown in Figure 1 , in an embodiment, the signal-idler photon separation optical path 2 comprises two first unequal arm Mach-Zehnder interferometers 21, the input ends of which are connected with the output end of the super entangled state generation optical path 1, and the output ends of which are connected with the input end of the energy-time degree of freedom analysis optical path 3.

[0030] As shown in Figure 2 , in an embodiment, the first unequal arm Mach-Zehnder interferometer 21 comprises a long arm waveguide and a short arm waveguide, a second thermo-optic phase shifter 22 arranged on the long arm waveguide or the short arm waveguide, or two second thermo-optic phase shifters 22 arranged on the long arm waveguide and the short arm waveguide respectively, a first multimode interferometer 51 which is a 1x2 multimode interferometer, one input end of which is connected with the output end of the super entangled state generation optical path 1, and two output ends of which are connected with one end of the long arm waveguide and the short arm waveguide respectively, and a second multimode interferometer 52 which is a 2x2 multimode interferometer, two input ends of which are connected with the other end of the long arm waveguide and the short arm waveguide respectively, and two output ends of which are connected with the input end of the polarization degree of freedom analysis optical path 4 respectively.

[0031] Further, the second thermo-optic phase shifter 22 arranged on the long arm waveguide and the short arm waveguide of the two first unequal arm Mach-Zehnder interferometers 21 can be arranged according to actual needs, that is, one second thermo-optic phase shifter 22 can be arranged on one waveguide of each first unequal arm Mach-Zehnder interferometer 21, one second thermo-optic phase shifter 22 can be arranged on two waveguides of each first unequal arm Mach-Zehnder interferometer 21, one second thermo-optic phase shifter 22 can be arranged on one waveguide of one first unequal arm Mach-Zehnder interferometer 21, and one second thermo-optic phase shifter 22 can be arranged on two waveguides of the other first unequal arm Mach-Zehnder interferometer 21, as long as the signal-idler photon pair can be separated.

[0032] The signal-idler photon pair excited by the hyperentangled state generation optical path 1 enters the signal-idler photon separation optical path 2 through the first multimode interferometer 51. The signal-idler photon separation optical path 2 is composed of two identical first unequal arm Mach-Zehnder interferometers 21 arranged above and below. The first unequal arm Mach-Zehnder interferometer 21 is composed of a 1x2 first multimode interferometer 51, a 2x2 second multimode interferometer 52 and a second thermo-optic phase shifter 22. The first unequal arm Mach-Zehnder interferometer 21 includes a long arm waveguide and a short arm waveguide.

[0033] The present application can realize that the signal photons are in interference phase at the upper side output port of the first unequal arm Mach-Zehnder interferometer, and the idler photons are in interference phase at the upper side output port of the first unequal arm Mach-Zehnder interferometer by designing the length difference of the long arm waveguide and the short arm waveguide and controlling the second thermo-optic phase shifter on one arm. Correspondingly, the signal photons are in interference phase at the lower side output port of the first unequal arm Mach-Zehnder interferometer, and the idler photons are in interference phase at the lower side output port of the first unequal arm Mach-Zehnder interferometer. Finally, the signal photons and the idler photons are output from the upper side and the lower side of the first unequal arm Mach-Zehnder interferometer, respectively, so as to separate the signal and idler photons.

[0034] As Figure 1As shown in the embodiment, the energy-time degree of freedom analysis light path 3 comprises four second unequal arm Mach-Zehnder interferometers 32, each of which comprises a long arm waveguide, a short arm waveguide, a third multimode interferometer 53, a fourth multimode interferometer 54, an input port and two output ports, the input port is connected with the signal-idler photon separation light path 2, the third multimode interferometer 53 is a 1x2 multimode interferometer, which is arranged between the input port and the long arm waveguide and the short arm waveguide, the fourth multimode interferometer 54 is a 2x2 multimode interferometer, which is arranged between the long arm waveguide, the short arm waveguide and the two output ports; four optical delay line waveguides 31 are arranged on the long arm waveguides of the second unequal arm Mach-Zehnder interferometers 32 respectively; a plurality of second photodetectors 33 are arranged at one output port of each second unequal arm Mach-Zehnder interferometer 32; the other output port of the second unequal arm Mach-Zehnder interferometer 32 is connected with the input end of the polarization degree of freedom analysis light path 4.

[0035] As shown in the embodiment, Figure 1 , 2 As shown in the embodiment, the second unequal arm Mach-Zehnder interferometer 32 comprises a third thermo-optic phase shifter 34 arranged on the long arm waveguide or the short arm waveguide; or two third thermo-optic phase shifters 34 arranged on the long arm waveguide and the short arm waveguide respectively.

[0036] Further, the third thermo-optic phase shifters 34 arranged on the long arm waveguides and the short arm waveguides of the four second unequal arm Mach-Zehnder interferometers 32 can be arranged according to actual needs, that is, one third thermo-optic phase shifter 34 can be arranged on one waveguide of each second unequal arm Mach-Zehnder interferometer 32, or one third thermo-optic phase shifter 34 can be arranged on each waveguide of each second unequal arm Mach-Zehnder interferometer 32, or one third thermo-optic phase shifter 34 can be arranged on one waveguide of a part of second unequal arm Mach-Zehnder interferometers 32, and one third thermo-optic phase shifter 34 can be arranged on each waveguide of another part of second unequal arm Mach-Zehnder interferometers 32, as long as the signal photons and idler photons can be analyzed on the energy-time degree of freedom.

[0037] The separated signal-idler photons enter the energy-time degree of freedom analysis optical path 3. The energy-time degree of freedom analysis optical path 3 is composed of four identical second unequal arm Mach-Zehnder interferometers 32 from top to bottom. The second unequal arm Mach-Zehnder interferometer 32 in the energy-time degree of freedom analysis optical path 3 is similar to the first unequal arm Mach-Zehnder interferometer 21 in the signal-idler photon separation optical path 2, except that the long arm waveguide part of the second unequal arm Mach-Zehnder interferometer 32 is provided with an optical delay line waveguide 31, and the length difference between the two waveguides is larger; in addition, one output port of the second unequal arm Mach-Zehnder interferometer 32 is connected to a second photodetector 33 for monitoring the working state of the energy-time degree of freedom analysis optical path 3, and the other output port is used for outputting the entangled state. For the sake of convenience, it is assumed that the second unequal arm Mach-Zehnder interferometer 32 from top to bottom is 、 、 、 photons enter the second unequal arm Mach-Zehnder interferometer 32.

[0038] First, only the 、 photons are considered, when 、 photons enter the respective second unequal arm Mach-Zehnder interferometers 32, there is a half chance to go through the long arm waveguide and the short arm waveguide. If 、 the length of the waveguide is different, the arrival time of the photons can be detected by single photon counters and time digital converters, etc., to obtain the arrival time difference of 、 , thereby obtaining the path information of the photons; if 、 go through the long arm waveguide, or go through the short arm waveguide, the arrival time of the photons cannot distinguish the two cases, so the path information of the photons is erased, and can be analyzed in the time-energy dimension, which is specifically manifested as the output photon coincidence counting of the two second unequal arm Mach-Zehnder interferometers 32 changes with the phase difference of the second unequal arm Mach-Zehnder interferometer 32. By post-selection of the arrival time of the photons, the time-energy entangled state can be expressed as:

[0039] wherein represents that the signal and idler photons go through the long arm, represents that the signal and idler photons go through the short arm, represents the sum of the phase difference of the two arms of the interferometer in which the signal and idler photons are located. The analysis of 、 photons is the same as above.

[0040] This invention enables the analysis of signal photons and idler photons in the energy-time degree of freedom by setting up an energy-time degree of freedom analytical optical path 3.

[0041] like Figure 1 As shown, in one embodiment, the polarization degree-of-freedom analytical optical path 4 includes: two equal-arm Mach-Zehnder interferometers 42, each having two input ports; and two fourth thermo-optical phase shifters 41, each disposed at one input port of each of the equal-arm Mach-Zehnder interferometers 42, the input ports being connected to the other output ports of the two second unequal-arm Mach-Zehnder interferometers 32 in the energy-time degree-of-freedom analytical optical path 3.

[0042] like Figure 1 , 2 As shown, in one embodiment, the equal-arm Mach-Zehnder interferometer 42 further includes: two waveguides of equal length; a fifth multimode interferometer 55, which is a 2×2 multimode interferometer, disposed between the input port of the equal-arm Mach-Zehnder interferometer 42 and the two waveguides of equal length; a sixth multimode interferometer 56, which is a 2×2 multimode interferometer, disposed between the output port of the equal-arm Mach-Zehnder interferometer 42 and the two waveguides of equal length; a fifth thermo-optical phase shifter 43 disposed on one of the waveguides; or two fifth thermo-optical phase shifters 43, respectively disposed on the two waveguides.

[0043] Furthermore, the fifth thermo-optical phase shifter 43 set on the two equal-arm waveguides of the two equal-arm Mach-Zehnder interferometers 42 can be set according to actual needs. It can be set on one waveguide of one equal-arm Mach-Zehnder interferometer 42, or one fifth thermo-optical phase shifter 43 can be set on each of the two waveguides of each equal-arm Mach-Zehnder interferometer 42, or one fifth thermo-optical phase shifter 43 can be set on one waveguide of one equal-arm Mach-Zehnder interferometer 42 and one fifth thermo-optical phase shifter 43 can be set on each of the two waveguides of the other equal-arm Mach-Zehnder interferometer 42. As long as it can satisfy the requirement of resolving the polarization degrees of freedom of signal photons and idler photons, it is acceptable.

[0044] like Figure 1 , 2 As shown, in one embodiment, after the other input ports of the two equal-arm Mach-Zehnder interferometers 42 cross, they are respectively connected to the other output ports of the other two second unequal-arm Mach-Zehnder interferometers 32 in the energy-time degree of freedom analytical optical path 3.

[0045] The photons after time-energy degree of freedom analysis enter the polarization degree of freedom analysis optical path 4. The polarization degree of freedom analysis optical path 4 comprises two equal-arm Mach-Zehnder interferometers 42, wherein the upper equal-arm Mach-Zehnder interferometer 42 is used for interference of signal photons, and the lower equal-arm Mach-Zehnder interferometer 42 is used for interference of idler photons, so 、 The photons first need to pass through the waveguide cross structure to realize photon routing, at this time 、 Enter two input ports of the upper equal-arm Mach-Zehnder interferometer 42, 、 Enter two input ports of the lower equal-arm Mach-Zehnder interferometer 42. Through the structure of the equal-arm Mach-Zehnder interferometer 42 and the fourth thermo-optic phase shifter 41 in front of the equal-arm Mach-Zehnder interferometer 42, polarization degree of freedom analysis can be realized. For the transmission characteristics of a single equal-arm Mach-Zehnder interferometer 42, the Jones matrix can be used to describe:

[0046] Wherein is the phase difference of the two arms of the interferometer, is the phase difference introduced by the thermo-optic phase shifter in front of the interferometer. For the input light field , the output light fields are respectively

[0047] The conversion from any polarization state to any polarization state can be realized by adjusting the phase difference of the equal-arm Mach-Zehnder interferometer 42 in front of the phase of the two waveguides, that is, any measurement basis vector can be constructed, so as to realize polarization state analysis. At this time, the hyperentangled state is the tensor product of two entangled states, which can be expressed as:

[0048] The present application is based on the integrated optical platform to prepare hyperentangled states, and the polarization rotation beam splitter is used to convert the polarization information of the entangled state into path information, so that in the analysis process, the light field can be transmitted in the waveguide in a stable TE mode, avoiding the rotation of the polarization of the light field in the transmission process, and ensuring that the polarization information does not affect the analysis process of the energy-time degree of freedom; for energy-time degree of freedom analysis, the light delay line waveguide structure can significantly reduce the area of the unbalanced interferometer; after the energy-time degree of freedom analysis is completed, the path information is restored to the polarization information through the waveguide cross structure and the equal-arm Mach-Zehnder interferometer structure, and the polarization degree of freedom analysis is realized. The above entangled state preparation and analysis optical path can analyze the two degrees of freedom of the hyperentangled state at the same time, effectively improving the analysis efficiency of the hyperentangled state.

[0049] In the description of the present application, it should be noted that the terms "upper", "lower", and the like are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise expressly specified and limited, the terms "mounting", "connecting", "connecting" should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0050] It should be noted that in the present application, relational terms such as "first" and "second" and the like are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the sentence "including a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0051] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A photonic super-entangled state analysis device, characterized in that, include: The super-entangled state generation optical path (1) has a pump light input terminal on one side and a signal-idle photon pair output terminal on the other side. The pump light enters the super-entangled state generation optical path (1) through the pump light input terminal to generate a signal-idle photon pair. The signal-idle photon separation optical path (2) is provided with an input end and an output end. Its input end is connected to the signal-idle photon pair output end of the super-entangled state generation optical path. The signal-idle photon pair is separated into signal photons and idler photons by the signal-idle photon separation optical path (2). The energy-time degree of freedom analysis optical path (3) has an input end and an output end. Its input end is connected to the output end of the super-entangled state generation optical path. The separated signal photon and idler photon are analyzed by energy-time degree of freedom through the energy-time degree of freedom analysis optical path (3). The polarization degree of freedom resolution optical path (4) has an input end, which is connected to the output end of the energy-time degree of freedom resolution optical path. The signal photon and idler photon after energy-time degree of freedom resolution are polarized degree of freedom resolution through the polarization degree of freedom resolution optical path (4).

2. The photonic super-entangled state analysis device according to claim 1, characterized in that, The optical path for generating the super-entangled state includes: A polarization rotating beam splitter (11) is provided with an input end and an output end. Its input end is connected to the pump light input end of the super-entangled state generation optical path (1). The polarization rotating beam splitter (11) is used to rotate and separate the pump light into a clockwise light field and a counterclockwise light field. The micro-ring (12) has an input end and an output end. Its input end is connected to the output end of the polarization rotation beam splitter (11), and its output end is connected to the signal-idle photon pair output end of the super-entangled state generation optical path (1). The micro-ring (12) is used to generate signal-idle photon pairs by exciting nonlinear effects in the separated clockwise and counterclockwise light fields.

3. The photonic super-entangled state analysis device according to claim 2, characterized in that, The super-entangled state generation optical path (1) further includes: A first thermo-optical phase shifter (13) is disposed between the polarization rotating beam splitter (11) and the micro-ring (12), and the first thermo-optical phase shifter (13) is used to change the phase of the clockwise optical field; The first photodetector (14), which is connected in parallel with the first thermo-optical phase shifter (13), is located between the polarization rotating beam splitter (11) and the micro-ring (12). The first photodetector (14) is used to monitor the light field intensity in the counterclockwise direction.

4. The photonic super-entangled state analysis device according to claim 1, characterized in that, The signal-idle photon separation optical path (2) includes: Two first unequal arm Mach-Zehnder interferometers (21) have their input ends connected to the output end of the signal-idle photon pair of the super-entangled state generation optical path (1), and their output ends connected to the input end of the energy-time degree of freedom analytical optical path (3).

5. The photonic super-entangled state analysis device according to claim 4, characterized in that, The first unequal-arm Mach-Zehnder interferometer (21) includes: One long-arm waveguide and one short-arm waveguide; A second thermo-optical phase shifter (22) is disposed on one long-arm waveguide or one short-arm waveguide; or two second thermo-optical phase shifters (22) are disposed on one long-arm waveguide and one short-arm waveguide, respectively. The first multimode interferometer (51) is a 1×2 multimode interferometer. One of its input terminals is connected to the output terminal of the signal-idle photon pair of the super-entangled state generation optical path (1), and its two output terminals are respectively connected to one end of the long arm waveguide and one end of the short arm waveguide. The second multimode interferometer (52) is a 2×2 multimode interferometer. Its two input ends are connected to the other ends of the long arm waveguide and the short arm waveguide, respectively, and its two output ends are connected to the input ends of the polarization degree of freedom analytical optical path (4).

6. The photonic super-entangled state analysis device according to claim 1, characterized in that, The energy-time degree of freedom analytical optical path (3) includes: Four second unequal-arm Mach-Zehnder interferometers (32) are provided, each including a long-arm waveguide, a short-arm waveguide, a third multimode interferometer (53), a fourth multimode interferometer (54), an input port, and two output ports. The input port is connected to the signal-idle photon separation optical path (2). The third multimode interferometer (53) is a 1×2 multimode interferometer and is located between the input port and the long-arm waveguide and the short-arm waveguide. The fourth multimode interferometer (54) is a 2×2 multimode interferometer and is located between the long-arm waveguide, the short-arm waveguide, and the two output ports. Four optical delay line waveguides (31) are respectively disposed on the long arm waveguides of multiple second unequal arm Mach-Zehnder interferometers (32); Multiple second photodetectors (33) are respectively located at one output port of each second unequal-arm Mach-Zehnder interferometer (32); The other output port of the second unequal-arm Mach-Zehnder interferometer (32) is connected to the input of the polarization degree of freedom analytical optical path (4).

7. The photonic super-entangled state analysis device according to claim 6, characterized in that, The second unequal-arm Mach-Zehnder interferometer (32) includes: A third thermo-optical phase shifter (34) is disposed on one long-arm waveguide or one short-arm waveguide; or two third thermo-optical phase shifters (34) are disposed on one long-arm waveguide and one short-arm waveguide, respectively.

8. The photonic super-entangled state analysis device according to claim 5, characterized in that, The polarization degree of freedom analytical optical path (4) includes: Two equal-arm Mach-Zehnder interferometers (42) are provided with two input ports respectively; Two fourth thermo-optical phase shifters (41) are respectively located at one input end of each of the equal-arm Mach-Zehnder interferometers (42), and the input ends are connected to the other output ports of the two second unequal-arm Mach-Zehnder interferometers (32) in the energy-time degree-of-freedom analytical optical path (3).

9. The photonic super-entangled state analysis device according to claim 8, characterized in that, The equal-arm Mach-Zehnder interferometer (42) also includes: Two waveguides of equal length; The fifth multimode interferometer (55) is a 2×2 multimode interferometer, which is located between the input port of the equal-arm Mach-Zehnder interferometer (42) and two waveguides of equal length; The sixth multimode interferometer (56), which is a 2×2 multimode interferometer, is located between the output port of the equal-arm Mach-Zehnder interferometer (42) and two waveguides of equal length; A fifth thermo-optical phase shifter (43) is disposed on one of the waveguides; or two fifth thermo-optical phase shifters (43) are disposed on the two waveguides respectively.

10. The photonic super-entangled state analysis device according to claim 8, characterized in that: After the other input ports of the two equal-arm Mach-Zehnder interferometers (42) cross, they are respectively connected to the other output ports of the other two second unequal-arm Mach-Zehnder interferometers (32) in the energy-time degree of freedom analytical optical path (3).

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