A method for generating non-Hermitian three-photon correlations by multi-wave mixing

Abstract

The present invention relates to the field of quantum communication, and in particular to a method for generating non-Hermitian three-photon correlation by multi-wave mixing, the method comprising the following steps: providing a non-Hermitian system; under the action of a decoration field, applying a first polarized light, a second polarized light and a third polarized light after adjusting the incident parameters to the non-Hermitian system at the same time, causing a spontaneous six-wave mixing process, and generating entangled three-photons; by adjusting the ratio of the Rabi frequency and the out-of-phase rate of the decoration field of the non-Hermitian system, the change in the number of coherent channels of the real part and the imaginary part of the energy level eigenstate is determined, and the photon counting rate of the entangled three-photons when the number of coherent channels of the real part and the imaginary part of the energy level eigenstate is the largest is measured to obtain a correlation function. The method of the present invention improves the quantum information capacity by increasing the number of multi-channels dominated by real and imaginary, and solves the problems of low coupling degree of entangled three-photons, low generation efficiency, and low maximum resolution of counting modules in the existing method for generating entangled three-photons.

Description

Technical Field

[0001] The invention belongs to the field of quantum communication, and in particular relates to a method for generating non-Hermitian three-photon correlation by multi-wave mixing. Background Art

[0002] The non-Hermitian property of the photon entangled state refers to the property of the system exchanging energy with the surrounding environment.

[0003] The non-Hermitian phase transition of a three-photon entangled source refers to the degeneration of multiple eigenvalues ​​and corresponding eigenvectors in the system.

[0004] The study of quantum sources, especially multi-photon entangled states, will help promote the application of quantum technology in quantum computing and communication, such as quantum key distribution and multi-body quantum communication. As the demand for multi-body quantum information processes increases, the number of controllable photons is also increasing. Compared with two-photons, three-photon entangled sources have higher security, flexibility, and information capacity. Therefore, constructing three-photon correlation is a direction worth studying.

[0005] There are currently two methods for generating entangled three-photons, namely the crystal method and the rubidium atom cascade method. The crystal method uses the spontaneous parametric down-conversion process in nonlinear crystals, combined with a polarization beam splitter, to generate multi-body entangled photons. However, due to multiple repeated processes, further calibration is required, resulting in low efficiency and prone to loss problems, resulting in a low maximum resolution of the counting module. The rubidium atom cascade method uses a four-wave mixing nonlinear process in an atomic system to generate multi-body entangled photons by cascading. However, the cascade method also has problems such as low coupling degree of entangled three-photons, low generation efficiency, and long experimental measurement cycle.

[0006] Based on this, it is necessary to improve the existing method of generating entangled three-photons in order to enhance the coupling anti-interference capability and quantum information capacity. Summary of the invention

[0007] In order to solve the problems of low coupling degree of entangled three-photons, low generation efficiency and low maximum resolution of counting modules in existing methods for generating entangled three-photons, the purpose of the present invention is to provide a method for generating non-Hermitian three-photon correlations by multi-wave mixing.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows.

[0009] The present invention provides a method for generating non-Hermitian three-photon correlation by multi-wave mixing, comprising the following steps:

[0010] providing a non-Hermitian system having an energy level structure in which atomic spin states depend on atomic interactions;

[0011] Passing the three laser beams through corresponding half-wave plates and polarization beam splitters in sequence to generate first polarized light, second polarized light and third polarized light respectively;

[0012] Under the action of the decorated field, the first polarized light, the second polarized light and the third polarized light after adjusting the incident parameters are simultaneously applied to the non-Hermitian system, and a spontaneous six-wave mixing process occurs; in the spontaneous six-wave mixing process, the first polarized light, the second polarized light and the third polarized light are coupled through a nonlinear process to generate entangled three photons;

[0013] By adjusting the ratio of the Rabi frequency and the out-of-phase rate of the dressed field in the non-Hermitian system, the change in the number of coherent channels of the real and imaginary parts of the energy level eigenstates is determined, and the photon counting rate of the entangled three photons is measured when the number of coherent channels of the real and imaginary parts of the energy level eigenstates is maximum to obtain the correlation function.

[0014] The present invention adjusts the first polarized light, the second polarized light and the third polarized light of the incident parameters and applies them to a non-Hermitian system, causing a spontaneous six-wave mixing process to generate entangled three-photons, and realizes the conversion from real multi-channel to imaginary multi-channel by adjusting the ratio of the Rabi frequency and the out-of-phase rate of the decorated field, thereby increasing the number of multi-channels dominated by real and imaginary, and improving the quantum information capacity, thereby solving the problems of low coupling degree of entangled three-photons, low generation efficiency and low maximum resolution of the counting module in the existing method for generating entangled three-photons.

[0015] Preferably, the first polarized light and the second polarized light are both horizontally polarized light; and the third polarized light is vertically polarized light;

[0016] The method of adjusting the incident parameters of the first polarized light, the second polarized light and the third polarized light is:

[0017] The incident direction of the second polarized light is adjusted so that the second polarized light propagates in the non-Hermitian system in a direction opposite to that of the first polarized light; at the same time, the incident frequency of the second polarized light is adjusted so that the difference between the incident frequency of the second polarized light and the incident frequency of the first polarized light is 3 GHz; the incident direction of the third polarized light is adjusted so that the first polarized light and the third polarized light propagate in the non-Hermitian system in the same direction, and the angle between the first polarized light and the third polarized light is 0.48°; at the same time, the incident frequency of the third polarized light is adjusted so that the difference between the incident frequency of the third polarized light and the incident frequency of the first polarized light is 0.8 GHz.

[0018] Preferably, the non-Hermitian system is a 115°C system having a nonlinear polarizability. 85 Rb atomic vapor system; 85 The inner wall of the Rb atomic vapor system has a paraffin coating. 85In the Rb atomic vapor system, 85 Rb atomic vapor medium.

[0019] Preferably, the energy level structure of the non-Hermitian system includes a ground state energy level, a second excited state energy level, a third excited state energy level and a fourth excited state energy level;

[0020] The method for generating entangled three-photon by coupling the first polarized light, the second polarized light and the third polarized light through a nonlinear process is specifically:

[0021] The first polarized light is injected into the non-Hermitian system. 85 The electron clouds of Rb atoms interact with each other, and a transition from the ground state energy level to the third excited state energy level occurs, accompanied by the first detuning amount;

[0022] Injecting a second polarized light into the non-Hermitian system, the second polarized light is coupled with the first polarized light, and a transition occurs from the second excited state energy level to the fourth excited state energy level, accompanied by a second detuning amount;

[0023] A third polarized light is injected into the non-Hermitian system, the third polarized light is coupled with the first polarized light, a transition occurs from a ground state energy level to a fourth excited state energy level, accompanied by a third detuning amount, and a pair of Stokes light and anti-Stokes light is generated;

[0024] At the same time, the second polarized light is coupled with the anti-Stokes light to generate a fourth light beam, and the fourth light beam is coupled with the second polarized light and the third polarized light to generate three entangled signal lights, namely, the first signal light, the second signal light and the third signal light.

[0025] Preferably, the spontaneous six-wave mixing process includes two spontaneous parametric down-conversion processes, namely a first spontaneous parametric down-conversion process and a second spontaneous parametric down-conversion process;

[0026] In the first spontaneous parametric down-conversion process, the first polarized light and the third polarized light are 85 Coupling occurs in the Rb vapor medium, and two electromagnetically induced transparent windows are established during the coupling process, and a pair of Stokes light and anti-Stokes light are generated;

[0027] During the second spontaneous parametric down-conversion process, the second polarized light is coupled with the anti-Stokes light to generate a fourth light beam, and the fourth light beam is coupled with the second polarized light and the third polarized light to generate three photons in an entangled state, namely, a first signal light, a second signal light and a third signal light.

[0028] Preferably, the phase matching condition satisfied by the first spontaneous parametric down-conversion process is: 2k1=k S1 +k S2 ; Wherein, k1 is the wave vector of the first polarized light; k S1is the wave vector of the first signal light; k S2 is the wave vector of the second signal light;

[0029] The energy conservation condition satisfied by the conversion process under the first spontaneous parameter is: S1 =2ω1-ω S2 ; Wherein, ω1 is the frequency of the first polarized light; ω S1 is the frequency of the first signal light; ω S2 is the frequency of the second signal light.

[0030] Preferably, the energy conservation condition satisfied by the spontaneous six-wave mixing process is:

[0031] ω1+ω2+ω3=ω S1 +Δ1+ω S2 +Δ2+ω S3 +Δ3; where ω1 is the frequency of the first polarized light; ω2 is the frequency of the second polarized light; ω3 is the frequency of the third polarized light; ω S1 is the frequency of the first signal light; ω S2 is the frequency of the second signal light; ω S3 is the frequency of the third signal light; Δ1 is the first detuning amount; Δ2 is the second detuning amount; Δ3 is the third detuning amount;

[0032] The momentum conservation condition satisfied by the spontaneous six-wave mixing process is:

[0033] k1+k2+k3=k S1 +k S2 +k S3 ; Wherein, k1 is the wave vector of the first polarized light; k2 is the wave vector of the second polarized light; k3 is the wave vector of the third polarized light; k S1 is the wave vector of the first signal light; k S2 is the wave vector of the second signal light; k S3 is the wave vector of the third signal light.

[0034] Preferably, the method for measuring the photon count rate of the entangled three-photon when the number of coherent channels of the real part and the imaginary part of the eigenstate is maximum is specifically:

[0035] The splitting point of the energy level eigenstate is adjusted by adjusting the ratio of the Rabi frequency and the out-of-phase rate of the decorated field of the non-Hermitian system; and when the real part or the imaginary part of the energy level eigenstate becomes dominant, the number of coherent channels between the real part and the imaginary part of the energy level eigenstate is adjusted; the ratio point of the Rabi frequency and the out-of-phase rate of the decorated field when the number of coherent channels generated by the splitting of the real part and the imaginary part of the energy level eigenstate reaches the maximum is obtained, and the photon counting rate of the entangled three photons is measured at the ratio point.

[0036] Preferably, the method for obtaining the correlation function is specifically:

[0037] The entangled three photons pass through the corresponding single-photon detectors and output electrical signals. The electrical signal output by one of the single-photon detectors is divided into two signals by a power divider, and then input into the time-correlated single-photon counting module; by adjusting the Rabi frequency of the decorated field, the time correlation diagram of the three photons with entangled characteristics can be obtained.

[0038] Preferably, before obtaining the point where the ratio of the Rabi frequency and the out-of-phase rate of the decorated field reaches a maximum when the number of coherent channels generated by the splitting of the real and imaginary parts of the energy level eigenstates reaches the maximum, it also includes: obtaining the optimal experimental parameters for preparing the spin compression state by calculating the splitting of the real and imaginary parts of the energy level eigenstates.

[0039] Beneficial effects of the present invention:

[0040] 1. The present invention aims to achieve the conversion from real multi-channel to imaginary multi-channel by adjusting the ratio of the Rabi frequency and the out-of-phase rate of the decorated field to ensure the polarization mode and power regulation, so as to increase the number of multi-channels dominated by real and imaginary, thereby improving the quantum information capacity and achieving the purpose of system streamlining, and solving the problems of low coupling degree of entangled three-photons, low generation efficiency and low maximum resolution of the counting module in the existing method of generating entangled three-photons.

[0041] 2. The method of the present invention can achieve a high correlation time of entangled three-photon, enhance the coupling anti-interference capability, and improve the controllability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the principle of generating entangled three photons through a spontaneous six-wave mixing process in one embodiment of the present invention.

[0043] Among them, (a) and (b) are schematic diagrams from different perspectives, respectively. Figure 1 In the figure, SPDC1 represents the first spontaneous parametric down-conversion process; SPDC2 represents the second spontaneous parametric down-conversion process; SPDC3 represents the third spontaneous parametric down-conversion process; E1 represents the first polarized light; E2 represents the second polarized light; E3 represents the third polarized light; E S1 Indicates the first signal light; E S2 Indicates the second signal light; E S3 It is the third signal light.

[0044] Figure 2 FIG. 1 is an atomic energy level structure diagram of the entangled three-photon spontaneous six-wave mixing process in one embodiment of the present invention. Wherein, |1> represents the ground state energy level, and specifically {5S 1 / 2 , F=2}; |2> represents the second excited state energy level; and specifically {5S 1 / 2 ,F=3}; |3> represents the third excited state energy level; and specifically {5P 1 / 2}; |4> represents the third excited state energy level; and specifically {5P 2 / 3}.

[0045] Figure 3 The figure is a simulation result diagram of the three-photon coincidence counting rate of the single decoration effect in the case of damped Rabi oscillation in one embodiment of the present invention. Among them, (a1) is the three-dimensional function diagram of RCC dominated by the real part; (a2) is the simulation result diagram of the real part in the τ2 direction; (a3) ​​is the simulation result diagram of the real part in the τ3 direction; (b1) is the three-dimensional function diagram of RCC dominated by the imaginary part; (b2) is the simulation result diagram of the imaginary part in the τ2 direction; (b3) is the simulation result diagram of the imaginary part in the τ3 direction. τ represents the photon time; τ2 represents the second signal light time; τ3 represents the third signal light time. RCC, the full name in English is Reset and Clock Control, and the Chinese name is Reset and Clock Control.

[0046] Figure 4 1 and 2 are real multi-channel graphs and imaginary multi-channel graphs in one embodiment of the present invention. Among them, (a) is a real multi-channel graph in one embodiment of the present invention; (b) is an imaginary multi-channel graph in one embodiment of the present invention.

[0047] Figure 5 The graphs are the changes of cascade double decoration eigenvalues. Among them, (a1) is the change graph of the real part of the energy level eigenstate with the intensity of the main decoration field being 0.9EP; (a2) is the change graph of the real part of the energy level eigenstate with the intensity of the main decoration field being 1.0EP; (a3) ​​is the change graph of the real part of the energy level eigenstate with the intensity of the main decoration field being 1.1EP; (a4) is the change graph of the real part of the energy level eigenstate with the intensity of the main decoration field being 1.2EP; (b1) is the change graph of the imaginary part of the energy level eigenstate with the intensity of the main decoration field being 0.9EP; (b2) The graph showing the change of the imaginary part of the energy level eigenstate when the intensity of the main decoration field is 1.0EP; (b3) The graph showing the change of the imaginary part of the energy level eigenstate when the intensity of the main decoration field is 1.1EP; (b4) The graph showing the change of the imaginary part of the energy level eigenstate when the intensity of the main decoration field is 1.2EP; 0.9EP means 0.9 times of G2 at the EP point; 1.0EP means 1.0 times of G2 at the EP point; 1.1EP means 1.1 times of G2 at the EP point; 1.2EP means 1.2 times of G2 at the EP point. The ordinate is G2, which represents the intensity of the main decoration field; the abscissa is G3, which represents the intensity of the secondary decoration field. Re represents the real part; Im represents the imaginary part.

[0048] Figure 6The diagram shows the variation of nested double decoration eigenvalues. Among them, (a1) is the variation of the real part of the energy level eigenstate with the intensity of the main decoration field being 0.9EP; (a2) is the variation of the real part of the energy level eigenstate with the intensity of the main decoration field being 1.0EP; (a3) ​​is the variation of the real part of the energy level eigenstate with the intensity of the main decoration field being 1.1EP; (a4) is the variation of the real part of the energy level eigenstate with the intensity of the main decoration field being 1.2EP; (b1) is the variation of the imaginary part of the energy level eigenstate with the intensity of the main decoration field being 0.9EP; (b2) is the variation of the imaginary part of the energy level eigenstate with the intensity of the main decoration field being 1.0EP; (b3) is the variation of the imaginary part of the energy level eigenstate with the intensity of the main decoration field being 1.1EP; (b4) is the variation of the imaginary part of the energy level eigenstate with the intensity of the main decoration field being 1.2EP. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0051] In the following embodiments, EP point, also known as Exceptional Point in English and singular point in Chinese, is a special degenerate state unique to non-Hermitian systems (systems that exchange energy with the outside world), and usually energy level crossing and energy level repulsion occur near the EP point.

[0052] PT, the full English name is Parity-Time, and the Chinese name is Parity-Time.

[0053] PT symmetry, also known as space translation symmetry, states that the laws of physics do not depend on the choice of the origin of the spatial coordinate system. If the entire space is translated by one position, the laws of physics will not change.

[0054] PT symmetry breaking can be understood as the loss of symmetry elements, or the emergence of asymmetric factors in a system that originally had a higher symmetry, leading to a spontaneous decrease in the degree of symmetry.

[0055] EIT, the full name of which is Electromagnetic Induced Transparenc, is a physical phenomenon in which a laser beam, through the combined effects of electric and magnetic fields, affects the transition process between atomic energy levels, resulting in a significant reduction in the absorption rate of light at the atomic resonance absorption frequency, and even achieving completely transparent transmission of light at this frequency.

[0056] The SPDC process, whose full name is Spontaneous Parametric Down-Conversion in English, refers to the process of converting the frequency of a second-order nonlinear material into a state of flux. p The pump light interacts with the nonlinear material to generate a frequency of ω S The signal light and frequency are ω i The nonlinear process of idle light. This process needs to satisfy the energy conservation condition: ω p =ω S +ω i ; and the momentum conservation condition is satisfied: k p =k S +k i Among them, ω p is the frequency of the pump light; ω S is the frequency of the signal light; ω i is the frequency of idle light; k p is the wave vector of the signal light; k S is the wave vector of the pump light; k i is the wave vector of the idle light.

[0057] The present invention has previously studied the properties of two-photons in atomic systems, indicating that the cascade combination of multiple SPDCs can be used to obtain entangled three-photons, which is helpful for observing spontaneous four-wave mixing and spontaneous six-wave mixing processes. In the aforementioned study, the method used was to open two electromagnetically induced transparent windows at the same time in a nonlinear cold atomic system, and the six-wave mixing process generated entangled three-photons in a single step. The spontaneous six-wave mixing process is non-Hermitian, and the spatiotemporal characteristics of the entangled three-photons can be measured, and the number of coherent multi-channels of photons under different decoration fields can be calculated to improve the information capacity of the three-photons. However, the entangled three-photons generated by the aforementioned method have low coupling degree, weak nonlinear effect, and are not directly generated in one step, resulting in low efficiency. In addition, due to the use of a nonlinear cold atom system in the aforementioned cascade rubidium atomic pool, the noise generated by the entangled three-photons is large and there is much interference, so it cannot be directly applied to form a quantum device, and the three-photon count rate sampling resolution is low and the conversion efficiency is low.

[0058] Based on this, the present invention further studies the above method and obtains the 85 A spontaneous six-wave mixing process occurs in the Rb vapor medium, generating entangled three photons. By adjusting the intensity of the dressed field, the frequency coupling and wave-vector coupling of the coherent light are observed to induce nonlinear optical response.

[0059] During the parameter amplification process, nonlinear interactions occur between the laser beams, and effective optical pumping is achieved by extending the ground state coherence time. The first polarized light and the third polarized light propagate in the atomic medium in the same direction and the angle between the two is 0.48 degrees. The second polarized light propagates in the non-Hermitian system in the opposite direction to the first polarized light. The frequencies of the second polarized light and the third polarized light are obtained by shifting the first polarized light by 3 GHz and 0.8 GHz respectively through two acousto-optic modulators.

[0060] In order to achieve a high correlation time of three entangled photons, enhance the coupling anti-interference capability, improve the system controllability, and achieve the purpose of system simplification, the present invention increases the number of multi-channels dominated by real and virtual by adjusting the intensity of the decoration field, thereby improving the quantum information capacity.

[0061] The technical solution of the present invention is described in detail below, but it should not be understood as limiting the applicable scope of the present invention.

[0062] An embodiment of the present invention provides a method for generating non-Hermitian three-photon correlation by multi-wave mixing, comprising the following steps:

[0063] Step 1, providing a non-Hermitian system, wherein the non-Hermitian system has an energy level structure in which the atomic spin states depend on atomic interactions.

[0064] Step 2: Pass the three laser beams through corresponding half-wave plates and polarization beam splitters in sequence to generate a first polarized light, a second polarized light, and a third polarized light, respectively.

[0065] Step 3, under the action of the decorated field, the first polarized light, the second polarized light and the third polarized light after adjusting the incident parameters are simultaneously applied to the non-Hermitian system, and a spontaneous six-wave mixing process occurs; in the spontaneous six-wave mixing process, the first polarized light, the second polarized light and the third polarized light are coupled through a nonlinear process to generate entangled three photons.

[0066] Step 4, by adjusting the ratio of the Rabi frequency and the out-of-phase rate of the dressed field in the non-Hermitian system, the change in the number of coherent channels of the real and imaginary parts of the energy level eigenstates is determined, and the photon counting rate of the entangled three-photon when the number of coherent channels of the real and imaginary parts of the energy level eigenstates is maximum is measured to obtain the correlation function.

[0067] For step 1:

[0068] The non-Hermitian system has a nonlinear polarizability of 115 °C 85 Rb atomic vapor system; 85 The inner wall of the Rb atomic vapor system has a paraffin coating; 85 In the Rb atomic vapor system, 85Rb atomic vapor medium. In the parametric amplification process of the non-Hermitian system, nonlinear interaction occurs between laser beams, and effective optical pumping is achieved by extending the ground state coherence time.

[0069] The occurrence of spontaneous six-wave mixing is based on nonlinear 85 The rubidium atomic vapor medium is confined in an elongated cylindrical volume of length L. The three laser beams are coupled and focused by optical lenses. 85 In the Rb atomic vapor medium, the first polarized light is coupled with the third polarized light, and the second polarized light is coupled with the third polarized light.

[0070] For step 2:

[0071] In a preferred embodiment, three laser beams are generated by two lasers respectively, and the three laser beams are recorded as the first laser beam, the second laser beam and the third laser beam respectively. Among them, the first laser beam and the third laser beam are generated by the same semiconductor laser; the second laser beam is generated by another semiconductor laser. After the three laser beams come out of the corresponding semiconductor laser, they first pass through an isolator to filter out stray light and unstable components in the corresponding laser beams, and can prevent the generated reflected light from entering the corresponding semiconductor laser, so as to ensure the stable output of the corresponding semiconductor laser. Specifically:

[0072] After the first laser beam comes out of the first semiconductor laser, it first passes through the first isolator to filter out stray light and unstable components in the laser beam; then it passes through the first half-wave plate and the first polarization beam splitter prism to be divided into two beams of light, one of which is horizontally polarized light emitted by the first polarization beam splitter prism to obtain the first polarized light. The frequency of the first polarized light is denoted as ω1, the wave vector of the first polarized light is denoted as k1, the resonant transition frequency of the first polarized light is denoted as Ω1, the wavelength of the first polarized light is 780nm, and the first detuning amount is denoted as Δ1, which is -1.5GHz. The first detuning amount is obtained by scanning the first semiconductor laser. 85 The Rb atomic vapor system can be obtained before coupling, and the first detuning amount can be adjusted.

[0073] After the second laser beam comes out of the second semiconductor laser, it first passes through the second isolator to filter out stray light and unstable components in the laser beam; then it passes through the second half-wave plate and the second polarization beam splitter prism to be divided into two beams of light, one of which is horizontally polarized light and then emitted by the second polarization beam splitter prism to obtain the second polarized light. The frequency of the second polarized light is recorded as ω2, the wave vector of the second polarized light is recorded as k2, the resonant transition frequency of the second polarized light is recorded as Ω2, the wavelength of the second polarized light is 780nm, and the second detuning amount is recorded as Δ2, which is -4.5GHz.

[0074] After the third laser beam comes out of the first semiconductor laser, it first passes through the first isolator to filter out stray light and unstable components in the laser beam; then it passes through the third half-wave plate and the third polarization beam splitter prism to be divided into two beams of light, one of which is a vertically polarized light beam emitted by the third polarization beam splitter prism to obtain the third polarized light. The frequency of the third polarized light is recorded as ω3, the wave vector of the third polarized light is recorded as k3, the resonant transition frequency of the third polarized light is recorded as Ω3, the wavelength of the third polarized light is 795nm, and the third detuning amount is recorded as Δ3, which is -0.7GHz.

[0075] For step 3:

[0076] In a preferred embodiment, Figure 1 , the first polarized light and the second polarized light are both horizontally polarized light; and the third polarized light is vertically polarized light.

[0077] The method of adjusting the incident parameters of the first polarized light, the second polarized light and the third polarized light is:

[0078] The incident direction of the second polarized light is adjusted so that the second polarized light propagates in the non-Hermitian system in a direction opposite to that of the first polarized light; at the same time, the incident frequency of the second polarized light is adjusted so that the difference between the incident frequency of the second polarized light and the incident frequency of the first polarized light is 3 GHz; the incident direction of the third polarized light is adjusted so that the first polarized light and the third polarized light propagate in the non-Hermitian system in the same direction, and the angle between the first polarized light and the third polarized light is 0.48°; at the same time, the incident frequency of the third polarized light is adjusted so that the difference between the incident frequency of the third polarized light and the incident frequency of the first polarized light is 0.8 GHz.

[0079] Specifically, the first polarized light and the third polarized light generated by the first semiconductor laser are used as the first pump light and the third pump light respectively, and are transmitted along the same direction in 85 The second polarized light generated by the second semiconductor laser is transmitted in the opposite direction of the first polarized light as the second coupling light. 85 The second coupling light and the third pump light are propagated in the Rb atomic vapor medium. The frequencies of the second coupling light and the third pump light are obtained by shifting the first pump light by 3 GHz and 0.8 GHz respectively through two acousto-optic modulators.

[0080] In a preferred embodiment, the energy level structure of the non-Hermitian system includes a ground state energy level, a second excited state energy level, a third excited state energy level and a fourth excited state energy level; the first polarized light, the second polarized light and the third polarized light are coupled through a nonlinear process to generate entangled three photons, specifically:

[0081] The first polarized light is injected into the non-Hermitian system and 85 The electron clouds of Rb atoms interact, 85 The Rb atom transitions from the ground state energy level to the third excited state energy level, accompanied by a first detuning amount; the second polarized light is injected into the non-Hermitian system and coupled with the first polarized light, and a 85 The Rb atom transitions from the second excited state energy level to the fourth excited state energy level, accompanied by a second detuning amount; a third polarized light is injected into the non-Hermitian system and coupled with the first polarized light, resulting in 85 The transition of the Rb atom from the ground state energy level to the fourth excited state energy level, accompanied by the third detuning amount, produces a pair of Stokes light and anti-Stokes light; at the same time, the second polarized light is coupled with the anti-Stokes light to produce a fourth light beam, and the fourth light beam is coupled with the second polarized light and the third polarized light to produce entangled three photons.

[0082] In a preferred embodiment, the spontaneous six-wave mixing process includes two spontaneous parametric down-conversion processes, namely a first spontaneous parametric down-conversion process and a second spontaneous parametric down-conversion process:

[0083] In the first spontaneous parametric down-conversion process, the first polarized light and the third polarized light are 85 Coupling occurs in the Rb vapor medium, and two electromagnetically induced transparent windows are established during the coupling process, and a pair of Stokes light and anti-Stokes light are generated; specifically, the phase matching condition satisfied by the first spontaneous parametric down-conversion process is: 2k1 = k S1 +k S2 ; Wherein, k1 is the wave vector of the first polarized light; k S1 is the wave vector of the first signal light; k S2 is the wave vector of the second signal light; the energy conservation condition satisfied by the first spontaneous parametric down-conversion process is: ω S1 =2ω1-ω S2 ; Wherein, ω1 is the frequency of the first polarized light; ω S1 is the frequency of the first signal light; ω S2 is the frequency of the second signal light.

[0084] In the second spontaneous parametric down-conversion process, the second polarized light is coupled with the anti-Stokes light to generate a fourth light beam, and the fourth light beam is coupled with the second polarized light and the third polarized light to generate three entangled photons, namely, the first signal light, the second signal light and the third signal light. Specifically, the phase matching condition satisfied by the second spontaneous parametric down-conversion process is:

[0085] k1+k2+k3=k S1 +k S2 +k S3. Where k1 is the wave vector of the first polarized light; k2 is the wave vector of the second polarized light; k3 is the wave vector of the third polarized light; k S1 is the wave vector of the first signal light; k S2 is the wave vector of the second signal light; k S3 is the wave vector of the third signal light.

[0086] In a preferred embodiment, during the spontaneous six-wave mixing process, the energy conservation condition is: ω1+ω2+ω3=ω S1 +Δ1+ω S2 +Δ2+ω S3 +Δ3; where ω1 is the frequency of the first polarized light; ω2 is the frequency of the second polarized light; ω3 is the frequency of the third polarized light; ω S1 is the frequency of the first signal light; ω S2 is the frequency of the second signal light; ω S3 is the frequency of the third signal light; Δ1 is the first detuning amount; Δ2 is the second detuning amount; Δ3 is the third detuning amount.

[0087] In the second spontaneous parameter conversion process, the momentum conservation condition is satisfied:

[0088] k1+k2+k3=k S1 +k S2 +k S3 ; Wherein, k1 is the wave vector of the first polarized light; k2 is the wave vector of the second polarized light; k3 is the wave vector of the third polarized light; k S1 is the wave vector of the first signal light; k S2 is the wave vector of the second signal light; k S3 is the wave vector of the third signal light.

[0089] The entangled three-photon, that is, three photons in an entangled state, are the first signal light, the second signal light and the third signal light. The entangled three-photon not only affects the quantum properties, but also contributes to the high generation rate of the parameter amplification process in continuous frequency wavelength multiplexing.

[0090] The two mixing processes have the injection of the second coupling light, which will produce two pairs of amplified signals with quantum correlation, namely the first signal light and the third signal light, denoted as E S1 and E S3 , as well as the second signal light and the fourth light beam, denoted as E S2 and E S4 , a cascade six-wave mixing process occurs. The entangled three-photon not only affects the quantum properties but also contributes to the high generation rate of the parameter amplification process in continuous frequency wavelength multiplexing.

[0091] like Figure 2 and Figure 4In the spontaneous six-wave mixing process, in order to achieve pump regulation, the first polarized light, the second polarized light, and the third polarized light are respectively 85 Rb atoms interact with each other at different energy levels. The first polarized light achieves 85 The transition of Rb atoms from the ground state energy level to the third excited state energy level is respectively related to 85 The ground state energy level and the third excited state energy level of the Rb atom are coupled.

[0092] The second polarized light propagates in the direction toward the first polarized light and couples with the first polarized light to achieve 85 The Rb atom transitions from the second excited state energy level to the fourth excited state energy level; and 85 The second excited state energy level of the Rb atom is coupled to the fourth excited state energy level.

[0093] The third polarized light propagates along the direction of the first polarized light and couples with the first polarized light to achieve 85 The Rb atom transitions from the ground state energy level to the fourth excited state energy level; and 85 The fourth excited state energy level of the Rb atom is coupled to the fifth excited state energy level.

[0094] The fourth beam and 85 The second excited state energy level and the third excited state energy level of the Rb atom are coupled, such as Figure 1 As shown in Figure (b).

[0095] By adjusting the wavelengths of the first polarized light, the second polarized light and the third polarized light so that the three polarized lights can match the corresponding energy levels; and making the wavelength of the additionally generated fourth light beam also match the corresponding energy level, the designed transition between energy levels can be achieved.

[0096] For step 4:

[0097] The method for measuring the photon count rate of entangled three-photons when the number of coherent channels of the real and imaginary parts of the eigenstate is maximum is specifically: by adjusting the ratio of the Rabi frequency and the out-of-phase rate of the decorated field of the non-Hermitian system, the splitting point of the energy level eigenstate is adjusted; and when the real or imaginary part of the energy level eigenstate becomes dominant, the number of coherent channels between the real and imaginary parts of the energy level eigenstate is adjusted; the ratio point of the Rabi frequency and the out-of-phase rate of the decorated field is obtained when the number of coherent channels generated by the splitting of the real and imaginary parts of the energy level eigenstate reaches the maximum, and the photon count rate of the entangled three-photons is measured at the ratio point.

[0098] Preferably, the method for obtaining the correlation function is specifically as follows: the entangled three photons are respectively passed through corresponding single-photon detectors and output electrical signals, wherein the electrical signal output by one single-photon detector is divided into two signals by a power divider, and then input into a time-correlated single-photon counting module; by adjusting the Rabi frequency of the decorated field, a time correlation diagram of three photons with entanglement characteristics is obtained.

[0099] Preferably, before obtaining the point where the ratio of the Rabi frequency and the out-of-phase rate of the decorated field reaches a maximum when the number of coherent channels generated by the splitting of the real and imaginary parts of the energy level eigenstates reaches the maximum, it also includes: obtaining the optimal experimental parameters for preparing the spin compression state by calculating the splitting of the real and imaginary parts of the energy level eigenstates.

[0100] In a preferred embodiment, the real part or imaginary part of the energy level eigenstate becomes dominant, specifically: the real part or imaginary part of the energy level eigenstate is dominated by adjusting the ratio of the Rabi frequency and the out-of-phase rate of the decoration field. Specifically:

[0101] When the Rabi frequency of the dressing field is dominant, that is, the ratio of the Rabi frequency of the dressing field to the out-of-phase rate is greater than 1, the real part splits, resulting in in-phase structural dressing; when the out-of-phase rate is dominant, that is, the ratio of the Rabi frequency of the dressing field to the out-of-phase rate is less than 1, the imaginary part splits, resulting in out-of-phase destructive dressing.

[0102] However, no matter whether the real part is dominant or the imaginary part is dominant, the peak interpolation of the real eigenvalue is greater than the peak interpolation of the imaginary part; and the period of the real part is smaller than the period of the imaginary part. In the case where the real part is dominant or the imaginary part is dominant, the number of peaks and coherent channels that appear under different decoration fields corresponds one to one.

[0103] In the energy-level Hermitian coupling, different decoration combination states are considered, which will produce different coherent multi-channels of photons. For cascade double decoration and nested double decoration, under the main decoration field effect, cascade double decoration will experience second-order and third-order symmetry breaking, while nested double decoration will not produce such effect.

[0104] Cascade double decoration is in polarized light with 85 In a non-Hermitian system of Rb atoms interacting with each other, there are two or more dressing fields that affect the 85 The energy level structure of Rb atoms leads to more complex decorated states and dynamic behaviors.

[0105] Nested double dressing is to introduce one or more dressing fields into a non-Hermitian system that already has a dressing state. These newly introduced dressing fields interact with the original dressing state to form a more complex nested structure. Nested double dressing may make the energy level structure and dynamic behavior of the non-Hermitian system more complex and difficult to predict.

[0106] Under different dressing field strengths, the variation law of the eigenvalues ​​of cascaded double dressings and nested double dressings varies with the change of the strength of the main dressing field and the secondary dressing field. Among them, the influence of the main dressing field is more significant. In the non-Hermitian system of cascaded double dressings, the systematic order of the real and imaginary parts of the energy level eigenstates changes, and the signal width difference also changes. The variation law of the real and imaginary parts of the energy level eigenstates is opposite. In addition, the main dressing field and the secondary dressing field of cascaded double dressings and nested double dressings also have different effects on the eigenvalues, and there are also differences between the real and imaginary parts of the energy level eigenstates, which is reflected in the corresponding relationship between the first-order system and the second-order system, or in the transition from the Abelian group to the non-Abelian group.

[0107] Figure 5 It is a graph showing the change of cascade double decoration eigenvalues. When the intensity of the main decoration field is changed, the real and imaginary parts with the intensity of the secondary decoration field as the horizontal axis are observed to change, among which, (a1) is a graph showing the change of the real part of the energy level eigenstate when the intensity of the main decoration field is 0.9EP; (a2) is a graph showing the change of the real part of the energy level eigenstate when the intensity of the main decoration field is 1.0EP; (a3) ​​is a graph showing the change of the real part of the energy level eigenstate when the intensity of the main decoration field is 1.1EP; (a4) is a graph showing the change of the real part of the energy level eigenstate when the intensity of the main decoration field is 1.2EP; (b1) is a graph showing the change of the real part of the energy level eigenstate when the intensity of the main decoration field is 0.9EP. (b2) The imaginary part of the energy level eigenstate when the intensity of the main decoration field is 1.0EP; (b3) The imaginary part of the energy level eigenstate when the intensity of the main decoration field is 1.1EP; (b4) The imaginary part of the energy level eigenstate when the intensity of the main decoration field is 1.2EP; 0.9EP means 0.9 times G2 at the EP point; 1.0EP means 1.0 times G2 at the EP point; 1.1EP means 1.1 times G2 at the EP point; 1.2EP means 1.2 times G2 at the EP point. The ordinate is G2, which represents the intensity of the main decoration field; the abscissa is G3, which represents the intensity of the secondary decoration field. Re represents the real part; Im represents the imaginary part.

[0108] exist Figure 5 In Figures (a1) to (a4), the intensity of the main decoration field is taken as a multiple of G2 at the EP point to simulate the change process from the imaginary part to the real part, and the values ​​of the intensity of the main decoration field are 0.9EP, 1.0EP, 1.1EP and 1.2EP respectively. The ordinate is G2, which represents the intensity of the main decoration field; the abscissa is G3, which represents the intensity of the secondary decoration field. Re represents the real part; Im represents the imaginary part. According to the simulation in the figure, when G2 takes the real part, the order of the eigenvalues ​​changes, resulting in differentiation from the second-order system to the third-order system. In addition, the greater the intensity of the main decoration field, the greater the degree of differentiation, and the intensity ratio of the signal basically does not change.

[0109] exist Figure 5In Figures (b1) to (b4), the values ​​of G2 vary greatly, as mentioned above. As the strength of the secondary decoration field increases, the third-order system becomes a second-order system, indicating a transition from a non-Abelian group to an Abelian group. When the real part of G2 dominates, the order change of the eigenvalues ​​completely disappears and becomes an eigenvalue channel, which is consistent with the theoretical channel number. In addition, as the strength of the primary decoration field increases, the intensity ratio of the signal does not change substantially.

[0110] Figure 6 This is the nested double decoration eigenvalue change graph. As the intensity of the main decorating field changes, the changes in the real and imaginary parts with the secondary decorating intensity as the horizontal axis are observed, among which, (a1) is the change diagram of the real part of the energy level eigenstate when the intensity of the main decorating field is 0.9EP; (a2) is the change diagram of the real part of the energy level eigenstate when the intensity of the main decorating field is 1.0EP; (a3) ​​is the change diagram of the real part of the energy level eigenstate when the intensity of the main decorating field is 1.1EP; (a4) is the change diagram of the real part of the energy level eigenstate when the intensity of the main decorating field is 1.2EP; (b1) is the change diagram of the imaginary part of the energy level eigenstate when the intensity of the main decorating field is 0.9EP; (b2) is the change diagram of the imaginary part of the energy level eigenstate when the intensity of the main decorating field is 1.0EP; (b3) is the change diagram of the imaginary part of the energy level eigenstate when the intensity of the main decorating field is 1.1EP; (b4) is the change diagram of the imaginary part of the energy level eigenstate when the intensity of the main decorating field is 1.2EP.

[0111] exist Figure 6 In Figures (a1) to (a4), the size of the main decoration field is taken as a multiple of G2 at the EP point, and the change process from the imaginary part to the real part is observed. The intensity of the main decoration field is 0.9EP, 1.0EP, 1.1EP, and 1.2EP, respectively. The vertical axis is G2, which represents the intensity of the main decoration field; the horizontal axis is G3, which represents the intensity of the secondary decoration field. Re represents the real part; Im represents the imaginary part. According to Figure 6 In the results, when G2 takes the real part as the main factor, the order of eigenvalues ​​will not diverge. Figure 6 In the , all systems are third-order systems. The greater the intensity of the main decoration field, the greater the degree of fragmentation, and the intensity ratio of the signal will not change with the increase of the intensity of the main decoration field.

[0112] exist Figure 6 In Figures (b1) to (b4), the value of G2 varies greatly, as mentioned above. As the secondary decoration field increases, it is still a third-order system, showing an isomorphic mapping of the non-Abelian group. In addition, as the strength of the primary decoration field increases, the intensity ratio of the signal does not change substantially.

[0113] An embodiment of the present invention analyzes the distribution of eigenvalues, KAPPA and count rate intensity of single decoration, parallel double decoration, cascaded double decoration and nested double decoration under different decoration field strengths, as well as the correlation and difference between the real part and the imaginary part. The Chinese name of KAPPA is Kappa, which is a statistic that measures the consistency of test results. The count rate three-dimensional function is a three-dimensional graph that converts the frequency domain into the time domain by Laplace transforming the polarizability.

[0114] One embodiment of the present invention analyzes the changes in the number and intensity of eigenvalues ​​under the effect of the decorated field, and combines the analysis with the trend of the count rate oscillation period. It shows the transformation relationship of the influence of the decorated field on the PT system, time and space, real and imaginary parts, second and third orders, Abelian groups and non-Abelian groups.

[0115] The present invention adjusts the real and imaginary parts of the characteristic value by adjusting the Rabi frequency and loss. Figure 5 and Figure 6 , the present invention found that cascaded double decoration is an intermediate state. The reasons are as follows: first, the interaction strength of nested double decoration is greater than that of cascaded double decoration. In addition, in the case of single decoration and parallel double decoration, there is no interaction between the decoration fields, and there is interaction between the two decoration fields of cascaded double decoration and nested double decoration.

[0116] In addition, in one embodiment of the present invention, energy level decoration non-Hermitian control is performed by adjusting the ratio of the Rabi frequency and the out-of-phase rate of the decoration field of the non-Hermitian system, which is similar to the non-Hermitian control performed in microcavities / waveguides by the ratio of the coupling coefficient k and the loss / gain Γ. When the Rabi frequency of the decoration field is dominant, the real part splits, resulting in phase-consistent constructive decoration. When the dephasing rate is dominant, the imaginary part splits, resulting in phase-inconsistent destructive decoration. In a second-order system, the real part is local, non-degenerate, and has low symmetry, and its group is represented as an Abelian group. The imaginary part is non-local, degenerate, and has high symmetry, and the group is represented as a non-Abelian group. The peak interpolation of the real part eigenvalue is greater than the imaginary part, and the period is relatively small. In the double decoration field, the number of periods and coherent channels of the damped Rabi oscillation exceeds the case of only a single decoration field. When both the real and imaginary parts are dominant, the peaks and the number of coherent channels that appear under different decoration fields are one-to-one corresponding. However, the period of the real part is smaller than the period of the imaginary part.

[0117] In addition, for cascaded double decorations and nested double decorations, the present invention analyzes that under the action of the main decoration field, the cascaded double decoration will experience second-order and third-order symmetry breaking, while the nested double decoration will not produce this effect, which may be used in future quantum engine searches.

[0118] In a preferred embodiment, during the spontaneous six-wave mixing process, in a low-gain state, the entangled three photons are detected by three single-photon detectors, which are respectively denoted as SPCM1, SPCM2 and SPCM3.

[0119] In the spontaneous six-wave mixing process, the first polarized light, the second polarized light, and the third polarized light are focused onto the nonlinear coupler through an optical lens. 85 The center of the Rb atomic vapor medium is coupled, wherein the frequency of the incident first polarized light is ω1, and the first signal light and the first idle light are generated after spontaneous parametric down-conversion. The frequency of the incident second polarized light is ω2, and the second signal light and the second idle light are generated after spontaneous parametric down-conversion. The pump light frequency of the incident third polarized light is ω3, and the third signal light and the third idle light are generated after spontaneous parametric down-conversion, and detuning compensation is performed. In the process of spontaneous six-wave mixing, the energy conservation condition satisfied is ω1+ω2+ω3=ω S1 +Δ1+ω S2 +Δ2+ω S3 +Δ3; the momentum conservation condition is k1+k2+k3=k S1 +k S2 +k S3 . Among them, ω1 is the frequency of the first polarized light; ω2 is the frequency of the second polarized light; ω3 is the frequency of the third polarized light; ω S1 is the frequency of the first signal light; ω S2 is the frequency of the second signal light; ω S3 is the frequency of the third signal light; Δ1 is the first detuning amount; Δ2 is the second detuning amount; Δ3 is the third detuning amount.

[0120] The three-photon light is composed of the first signal light, the second signal light and the third signal light. The first signal light is denoted as E S1 , the second signal light is recorded as E S2 , the third signal light is recorded as E S3 , they pass through their corresponding single photon detectors and are detected by the corresponding single photon detectors, and output corresponding electrical signals. The single photon detector is denoted as SPCM, and the three single photon detectors are the first single photon detector, the second single photon detector and the third single photon detector, denoted as SPCM1, SPCM2, and SPCM3 respectively.

[0121] The second signal light directly outputs an electrical signal through the second single-photon detector; the third signal light directly outputs an electrical signal through the third single-photon detector. The electrical signal output by the first signal light through the first single-photon detector is divided into two signals through a power divider, and then input into the time-correlated single-photon counting module. By adjusting the Rabi frequency of the decorated field, the single-photon counting acquisition card is controlled by software to collect data and perform coincidence analysis operations to obtain a time correlation diagram of three photons with entanglement characteristics, which is consistent with the three-photon counting rate.

[0122] Figure 3 The figure is a simulation result diagram of the three-photon coincidence counting rate of the single decoration effect in the case of damped Rabi oscillation in one embodiment of the present invention. Among them, (a1) is the three-dimensional function diagram of RCC dominated by the real part; (a2) is the simulation result diagram of the real part in the τ2 direction; (a3) ​​is the simulation result diagram of the real part in the τ3 direction; (b1) is the three-dimensional function diagram of RCC dominated by the imaginary part; (b2) is the simulation result diagram of the imaginary part in the τ2 direction; (b3) is the simulation result diagram of the imaginary part in the τ3 direction. τ represents the photon time; τ2 represents the second signal light time; τ3 represents the third signal light time. RCC, the full name in English is Reset and Clock Control, and the Chinese name is Reset and Clock Control. Figure 3 In the figure, the Laplace transform of the polarizability is performed to convert the frequency domain into a three-dimensional graph in the time domain, and the three-dimensional function of the count rate is obtained, and the signal amplitude, period and coupling are simulated under different decoration field strengths. The two directions are τ2 and τ3. The highest signal point is usually located at the zero point. A signal change of 20ns is observed in the figure. When the real part occupies a dominant position, the count rate of τ2 is shown. When the real part occupies a dominant position, the τ2 eigenvalue has four peaks and can produce six cycles. Multi-cycle coupling produces a complex cosine signal.

[0123] When G3 is selected as 1.2EP, the real part dominates and τ3 has two distinct peaks, producing a period in which the signal decays over time. The RCC dominated by the imaginary part is shown, with the resonance position and linewidth swapped with the real part to analyze the case where G3 is 0.8EP. Figure 3 In Figure (b2), when the imaginary part dominates, dispersion and loss are exchanged. At this time, there are still four different peaks, resulting in six cycles. Figure 3 In (b3), the imaginary part of τ3 dominates and there is only one period. The reason is that there are two different peaks. This happens when G3 is 0.6 mW. When the dressing field deviates from the EP point, the period is relatively large.

[0124] In summary, the entangled three-photon generated by the spontaneous six-wave mixing process in the rubidium atomic vapor in the embodiment of the present invention induces nonlinear optical response by adjusting the frequency coupling and wave vector coupling of the coherent light observed by the decoration field intensity. In order to achieve the high correlation time of the entangled three-photon, improve the coupling anti-interference ability, and improve the controllability of the system, the present invention adjusts the decoration field intensity to increase the number of multi-channels dominated by real and virtual, thereby improving the quantum information capacity and achieving the purpose of system simplification, and solves the problems of low coupling degree of the entangled three-photon, low generation efficiency, and low maximum resolution of the counting module in the existing method of generating entangled three-photons.

[0125] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for generating non-Hermitian three-photon correlations by multi-wave mixing, characterized in that: The following steps are involved: A non-Hermitian system is provided, wherein the non-Hermitian system has an energy level structure in which the atomic spin states depend on the atomic interactions; the non-Hermitian system is 115°C with a nonlinear polarizability 85 Rb atomic steam system; Passing the three laser beams through corresponding half-wave plates and polarization beam splitters in sequence to generate first polarized light, second polarized light and third polarized light respectively; Under the effect of the decorated field, the first polarized light, the second polarized light and the third polarized light after adjusting the incident parameters are simultaneously applied to the non-Hermitian system, and a spontaneous six-wave mixing process occurs; In the spontaneous six-wave mixing process, the first polarized light, the second polarized light and the third polarized light are coupled through a nonlinear process to generate entangled three photons; By adjusting the ratio of the Rabi frequency and the out-of-phase rate of the decorated field in the non-Hermitian system, the change in the number of coherent channels of the real part and the imaginary part of the energy level eigenstate is determined, and the photon counting rate of the entangled three-photon when the number of coherent channels of the real part and the imaginary part of the energy level eigenstate is maximum is measured to obtain the correlation function; The method for measuring the photon counting rate of the entangled three-photon when the number of coherent channels of the real part and the imaginary part of the eigenstate is the largest is as follows: By adjusting the ratio of the Rabi frequency and the out-of-phase rate of the dressed field in the non-Hermitian system, the splitting point of the energy level eigenstate is adjusted; and when the real part or the imaginary part of the energy level eigenstate becomes dominant, the number of coherent channels between the real part and the imaginary part of the energy level eigenstate is adjusted; The ratio point of the Rabi frequency and the out-of-phase rate of the decorated field when the number of coherent channels generated by the splitting of the real and imaginary parts of the energy level eigenstate reaches a maximum is obtained, and the photon counting rate of the entangled three-photon is measured at the ratio point.

2. The method for generating non-Hermitian three-photon correlation by multi-wave mixing according to claim 1, characterized in that: The first polarized light and the second polarized light are both horizontally polarized light; the third polarized light is vertically polarized light; The method of adjusting the incident parameters of the first polarized light, the second polarized light and the third polarized light is: Adjusting the incident direction of the second polarized light so that the second polarized light propagates in the non-Hermitian system in a direction opposite to that of the first polarized light; and adjusting the incident frequency of the second polarized light so that the difference between the incident frequency of the second polarized light and the incident frequency of the first polarized light is 3 GHz; The incident direction of the third polarized light is adjusted so that the first polarized light and the third polarized light propagate in the non-Hermitian system in the same direction, and the angle between the first polarized light and the third polarized light is 0.48°; at the same time, the incident frequency of the third polarized light is adjusted so that the difference between the incident frequency of the third polarized light and the incident frequency of the first polarized light is 0.8 GHz.

3. The method for generating non-Hermitian three-photon correlation by multi-wave mixing according to claim 1, characterized in that: Said 85 The inner wall of the Rb atomic vapor system has a paraffin coating.

4. The method for generating non-Hermitian three-photon correlation by multi-wave mixing according to claim 3, characterized in that: The energy level structure of the non-Hermitian system includes a ground state energy level, a second excited state energy level, a third excited state energy level and a fourth excited state energy level; The method for generating entangled three-photon by coupling the first polarized light, the second polarized light and the third polarized light through a nonlinear process is specifically: The first polarized light is injected into the non-Hermitian system. 85 The electron clouds of Rb atoms interact with each other, and a transition occurs from the ground state energy level to the third excited state energy level, accompanied by the first detuning amount; Injecting a second polarized light into the non-Hermitian system, the second polarized light is coupled with the first polarized light, and a transition occurs from the second excited state energy level to the fourth excited state energy level, accompanied by a second detuning amount; A third polarized light is injected into the non-Hermitian system, the third polarized light is coupled with the first polarized light, a transition occurs from a ground state energy level to a fourth excited state energy level, accompanied by a third detuning amount, and a pair of Stokes light and anti-Stokes light is generated; At the same time, the second polarized light is coupled with the anti-Stokes light to generate a fourth light beam, and the fourth light beam is coupled with the second polarized light and the third polarized light to generate three entangled signal lights, namely, the first signal light, the second signal light and the third signal light.

5. The method for generating non-Hermitian three-photon correlation by multi-wave mixing according to claim 4, characterized in that: The energy conservation condition satisfied by the spontaneous six-wave mixing process is: ω1+ω2+ω3=ω S1 +Δ1+ω S2 +Δ2+ω S3 +Δ3; Wherein, ω1 is the frequency of the first polarized light; ω2 is the frequency of the second polarized light; ω3 is the frequency of the third polarized light; ω S1 is the frequency of the first signal light; ω S2 is the frequency of the second signal light; ω S3 is the frequency of the third signal light; Δ1 is the first detuning amount; Δ2 is the second detuning amount; Δ3 is the third detuning amount; The momentum conservation condition satisfied by the spontaneous six-wave mixing process is: k1+k2+k3=k S1 +k S2 +k S3 ; Wherein, k1 is the wave vector of the first polarized light; k2 is the wave vector of the second polarized light; k3 is the wave vector of the third polarized light; k S1 is the wave vector of the first signal light; k S2 is the wave vector of the second signal light; k S3 is the wave vector of the third signal light.

6. The method for generating non-Hermitian three-photon correlation by multi-wave mixing according to claim 1, characterized in that: The method to obtain the correlation function is: The entangled three photons pass through the corresponding single-photon detectors and output electrical signals. The electrical signal output by one of the single-photon detectors is divided into two signals by a power divider, and then input into the time-correlated single-photon counting module; by adjusting the Rabi frequency of the decorated field, the time correlation diagram of the three photons with entangled characteristics can be obtained.

7. The method for generating non-Hermitian three-photon correlation by multi-wave mixing according to claim 1, characterized in that: Before obtaining the ratio point of the Rabi frequency and the out-of-phase rate of the decorated field when the number of coherent channels generated by the splitting of the real and imaginary parts of the energy level eigenstate reaches the maximum, it also includes: obtaining the optimal experimental parameters for preparing the spin compressed state by calculating the splitting of the real and imaginary parts of the energy level eigenstate.

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