Rydberg atom electromagnetic signal detection device based on correlated photon coincidence measurement

Abstract

The invention provides a Rydberg atomic electromagnetic signal detection device based on correlated photon coincidence measurement, and the device comprises a correlated photon source assembly which is used for enabling single-polarization and frequency-stable laser to generate polarization orthogonal correlated photon pairs; the Rydberg atom preparation system is in communication connection with the associated photon source assembly, and associated photon pairs emitted by the associated photon source assembly enter the Rydberg atom preparation system; the correlation detection assembly is in communication connection with the Rydberg atom preparation system and is used for counting transmission photons of the EIT-AT split transmission spectrum signals, and when the difference value between the reference photon arrival time and the transmission photon arrival time is within a preset range, the EIT-AT split transmission spectrum signals are regarded as coincidence events and coincidence counts are recorded. According to the invention, the problem of low sensitivity caused by the defects of optical readout noise, weak off-resonance field response, sensitive temperature drift vibration environment and the like in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of quantum precision measurement technology, specifically to a Rydberg atom electromagnetic signal detection device based on correlated photon coincidence measurement. Background Technology

[0002] Electromagnetic signal detection devices are equipment that capture, convert, and process electromagnetic wave signals such as radio waves and microwaves in space through antennas, ultimately outputting identifiable data information. They are widely used in professional monitoring fields such as spectrum analysis, partial discharge, radar, and deep space communication. Existing electromagnetic signal receiving devices generally rely on metal antennas and electronic front-ends, and their electric field sensitivity is typically greater than 1 μV / cm / Hz due to limitations imposed by the thermal noise of electronic components. 1 / 2 This approach struggles to meet the demands of weak signal detection scenarios in professional monitoring fields. To address this low sensitivity, current electromagnetic signal detection devices attempt to improve sensitivity by measuring changes in the intensity of transmitted light passing through the atomic gas cell. Specifically, this involves employing electromagnetically induced transparency (EIT) and the Autler-Townes (AT) splitting effect, directly retrieving parameters such as electric field strength and polarization by measuring the spectral splitting distance induced by the microwave field. However, this detection method is constrained by factors such as shot noise in the probe light, thermal noise in the amplifier within the photodetector, and the number of Rydberg atoms involved in the interaction, preventing it from achieving a decisive advantage over traditional electromagnetic detection methods in terms of limiting sensitivity. Therefore, how to modify the detection mechanism to improve detection sensitivity is a crucial technical challenge that existing detection devices based on the Rydberg atom receiving system need to address. Summary of the Invention

[0003] This invention provides a Rydberg atom electromagnetic signal detection device based on correlated photon coincidence measurement. By using a collaborative detection method combining correlated photon coincidence measurement, Rydberg atom energy level modulation, and integrated optical path, it achieves the detection of electromagnetic signals such as microwaves and effectively improves the detection sensitivity. This solves the problem of low sensitivity caused by defects in the prior art, such as optical readout noise, weak non-resonant field response, and sensitivity to temperature drift and vibration environment.

[0004] The technical solution provided by this invention is as follows: A Rydberg atom electromagnetic signal detection device based on correlated photon coincidence measurement includes: Correlated photon source components are used to generate orthogonally correlated photon pairs from single-polarization and frequency-stable laser light. The Rydberg atom preparation system is communicatively connected to a correlated photon source component. Correlated photon pairs emitted from the correlated photon source component are incident on the Rydberg atom preparation system. The Rydberg atom preparation system forms a dual-wavelength laser field by using one photon from the correlated photon pair and a coupled light from the other photon pair. The dual-wavelength laser field interacts with the energy levels of cesium atoms to prepare Rydberg atoms. Then, after receiving electromagnetic wave signals incident along the polarization of the correlated photons, it outputs an EIT-AT split transmission spectrum signal carrying photon information and a reference light signal. The correlation detection component is connected in communication with the Rydberg atom preparation system. It is used to count reference photons in the received reference optical signal and to count transmitted photons in the EIT-AT split transmission spectrum signal. If the difference between the arrival time of the reference photon and the arrival time of the transmitted photon is within a preset range, it is considered a coincidence event and the coincidence count is recorded.

[0005] Preferably, the associated photon source component includes: The laser control module is used to stabilize the laser frequency and output the stabilized near-infrared laser. The quantum signal generation module is connected to the laser control module. Near-infrared laser emitted from the laser control module is incident on the quantum signal generation module. After the quantum signal generation module converts the near-infrared laser into ultraviolet laser, it generates polarization orthogonally correlated photon pairs in the nonlinear crystal through spontaneous parametric downconversion.

[0006] Preferably, the Reedberg atom preparation system includes: The probe optical channel is optically connected to the quantum signal generation module. A beam of vertically polarized light split from the polarized orthogonally correlated photon pair emitted by the quantum signal generation module serves as the probe light. After being parallel to a coupled light beam in the probe channel, the alkali metal atoms in the probe channel transition from the ground state to the Rydberg state. After the microwave signal is incident into the probe channel in the direction parallel to the probe light, the probe channel outputs an EIT-AT split transmission spectrum signal with information. The reference optical channel is optically connected to the quantum signal generation module. A horizontally polarized beam of light split from the polarization orthogonally correlated photon pairs emitted by the quantum signal generation module is used as the reference light and output through the reference optical channel.

[0007] Preferably, the correlation detection component includes: The detection module includes a first photon detection unit connected to the detection optical channel and a second photon detection unit connected to the reference optical channel. The EIT-AT split transmission spectrum signal emitted from the detection optical channel is incident on the first photon detection unit, which converts the vertically polarized photons of the EIT-AT split transmission spectrum signal into a first electrical pulse. The reference optical signal emitted from the reference optical channel is incident on the second photon detection unit, which converts the horizontally polarized photons in the reference optical signal into a second electrical pulse. The timestamp module is communicatively connected to the single-photon detection module and is used to time-stamp the arrival times of the first and second electric pulses. The conformity determination module is connected to the timestamp module and is used to determine the time difference between the arrival time of the first electrical pulse and the arrival time of the second electrical pulse. When the time difference is within a preset range, it is confirmed as a conformity event and the conformity count is output.

[0008] Preferably, the laser control module includes: The first laser is used to generate near-infrared laser with a wavelength of 852nm; The frequency stabilization unit is connected to the first laser via optical fiber. The 852nm near-infrared laser emitted from the first laser is incident on the third polarization beam splitter inside the frequency stabilization unit. The low-power probe light split by the third polarization beam splitter is incident on the cesium atom gas cell. The high-power pump light split by the third polarization beam splitter is reflected by multiple third mirrors and then incident parallel to the low-power probe light in the opposite direction to the cesium atom gas cell. The cesium atom gas cell emits a saturated absorption spectrum signal. The control unit is connected in communication with the frequency stabilization unit. It is used to modulate the saturated absorption spectrum signal and generate a frequency discrimination error signal. After passing through the PID control circuit, the error correction signal is output to the first laser, which controls the first laser to lock its output laser frequency to the atomic transition frequency of alkali metal atoms in the detection channel to the first excited state.

[0009] Preferably, the quantum signal generation module includes: The frequency doubling unit is connected to the frequency stabilizing unit via optical fiber. The near-infrared laser with a wavelength of 852nm emitted from the frequency stabilizing unit is split into vertically polarized light by the first polarizing beam splitter and then incident on the frequency doubling unit. The frequency doubling unit converts the near-infrared laser into an ultraviolet laser with a wavelength of 426nm by using a periodically polarized nonlinear crystal and controlling the temperature at the phase matching point. The temperature range controlled at the phase matching point is 190℃ to 210℃. An integrated optical path unit is connected to a frequency doubling unit via an optical fiber. The ultraviolet laser emitted from the frequency doubling unit is incident on the integrated optical path unit through a first reflecting mirror. The integrated optical path unit generates a quantum correlated state in the nonlinear crystal through spontaneous parametric downconversion. It outputs polarization orthogonally correlated photon pairs with horizontal and vertical polarization directions through dual-channel spatial separation. The wavelength matching of the polarization orthogonally correlated photon pairs detects the transition line of cesium atoms from the ground state to the first excited state in the optical channel.

[0010] Preferably, the detection optical channel includes: A microwave resonant cavity with a built-in cesium atom gas cell is connected to an integrated optical circuit unit via an optical fiber. The polarization-orthogonally correlated photon pairs emitted from the integrated optical circuit unit are separated into vertically polarized correlated photons by a second polarization beam splitter and then incident on the cesium atom gas cell. The cesium atoms in the cesium atom gas cell transition from the ground state (6S1 / 2) to the first excited state (6P3 / 2). A dichroic mirror is connected to the microwave resonant cavity via an optical fiber. A frequency-locked coupled beam is reflected by the dichroic mirror and incident on the cesium atom gas cell in the opposite direction of polarization-correlated photons. Cesium atoms in the cesium atom gas cell transition from the first excited state (6P3 / 2) to the Rydberg state with a principal quantum number greater than or equal to 50. The cesium atom gas cell receives electromagnetic wave signals incident in the same direction as the polarization-correlated photons and transmits them through the dichroic mirror as EIT-AT split transmission spectrum signals carrying photon quantity information.

[0011] The beneficial effects of this invention are: 1. The Rydberg atom electromagnetic signal detection device based on correlated photon coincidence measurement described in this invention generates orthogonally polarized correlated photon pairs from a single-polarized laser using a correlated photon source component. The Rydberg atom preparation system forms a dual-wavelength laser field by having one polarized correlated photon from the correlated photon pair interact with a coupled light source. The dual-wavelength laser field interacts with the energy levels of cesium atoms to prepare Rydberg atoms. Then, after receiving electromagnetic wave signals incident along the polarized correlated photon direction, it outputs an EIT-AT split transmission spectrum signal and a reference light signal to the correlated detection component. Finally, the correlated detection component performs coincidence counting on the correlated photon pairs to detect electromagnetic signals such as microwaves, and greatly improves the detection sensitivity.

[0012] 2. This invention achieves the detection of electromagnetic signals such as microwaves by using a correlated photon source component, a Rydberg atom preparation system, a correlated detection component, and their connection. Compared with the traditional electromagnetic signal detection method of the Rydberg transmission intensity method, this invention, based on correlated photon coincidence measurement, can greatly improve the detection sensitivity.

[0013] 3. This invention utilizes the temporal correlation of 852 nm correlated photon pairs and filters valid events of correlated photon pairs by conforming to time windows. It can effectively filter out environmental noise such as dark counting and ambient stray light, and effectively improve the signal-to-noise ratio compared with the traditional transmission intensity method.

[0014] 4. This invention ensures efficient excitation of Rydberg states by having 852 nm vertically polarized photons and 509 nm coupled light incident in opposite directions in the Rydberg atom preparation system; at the same time, the laser frequency stabilization module locks to the cesium atom transition line to ensure the stability of the EIT window. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the Rydberg atom electromagnetic signal detection device based on correlated photon coincidence measurement according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the associated photon source component according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the Rydberg atom preparation system described in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the first electrical pulse, the second electrical pulse, photons, and coincidence count statistics of correlated photon pairs in the absence of a microwave signal, as described in an embodiment of the present invention; wherein: Figure 4 a is a schematic diagram of the signal of the first electrical pulse detected by the correlation detection component when there is no microwave signal. Figure 4 b is a schematic diagram of the second electrical pulse detected by the correlation detection component when there is no microwave signal. Figure 4 c is the same as Figure 4 a. Schematic diagram of photon statistics corresponding to the vertical polarization state. Figure 4 d is with Figure 4 Schematic diagram of photon statistics for the horizontal polarization state corresponding to b. Figure 4 e is a schematic diagram of the coincidence count statistics output by the correlated detection component when there is no microwave signal; Figure 5 This is a schematic diagram illustrating the first electrical pulse, the second electrical pulse, photons, and coincidence counting statistics when a microwave signal is present, as described in an embodiment of the present invention; wherein: Figure 5 a is a schematic diagram of the first electrical pulse detected by the associated detection component when there is a microwave signal. Figure 5 b is a schematic diagram of the second electrical pulse detected by the associated detection component when there is a microwave signal. Figure 5 c is the same as Figure 5 a. Schematic diagram of photon statistics corresponding to the vertical polarization state. Figure 5 d is with Figure 5 Schematic diagram of photon statistics for the horizontal polarization state corresponding to b. Figure 5e is a schematic diagram of the coincidence count statistics output by the associated detection component when there is a microwave signal. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0017] As attached Figure 1 To be continued Figure 3 As shown, a Rydberg atom electromagnetic signal detection device based on correlated photon coincidence measurement includes a correlated photon source component, a Rydberg atom preparation system, and a correlated detection component.

[0018] The correlated photon source component is used to generate wavelength-complementary orthogonally correlated photon pairs from a single-polarization, frequency-stable laser. The correlated photon source component includes a laser control module and a quantum signal generation module.

[0019] The laser control module is used to stabilize the laser frequency and output the stabilized near-infrared laser. The laser control module includes a first laser, a frequency stabilization unit, and a control unit. The frequency stabilization unit is connected to the first laser via optical fiber, and the control unit is communicatively connected to the frequency stabilization unit.

[0020] Preferably, the first laser is used to generate near-infrared laser with a wavelength of 852nm, i.e., 852nm laser. The wavelength of the 852nm laser matches the transition frequency of cesium atoms from the first excited state to the Rydberg state, resulting in high wavelength accuracy. The frequency stabilization unit locks the laser frequency of the first laser to the cesium atom resonance frequency through PID feedback control, forming a saturated absorption effect and eliminating frequency drift caused by environmental disturbances. The frequency stabilization unit includes a third polarizing beam splitter, multiple third reflecting mirrors, and a cesium atom gas chamber.

[0021] The 852nm laser emitted from the first laser is incident on the third polarization beam splitter inside the frequency stabilization unit. The third polarization beam splitter splits the 852nm laser into a high-power pump beam and a low-power probe beam. The low-power probe beam is incident on the cesium atom gas chamber, while the high-power pump beam, after being reflected by two third mirrors, is incident on the cesium atom gas chamber in the opposite direction to the low-power probe beam. The cesium atoms change from their ground state (6S) to their 652nm state. 1 / 2 Transition to the first excited state (6P) 3 / 2Because cesium atoms have a weakened ability to absorb probe light, a saturation absorption effect occurs. The saturation absorption spectrum signal emitted from the cesium atom gas cell is converted into an electrical signal by a photodetector and sent to the control unit. In this embodiment, if the pump light power is too low, the signal-to-noise ratio of the saturation absorption peak will be insufficient. Therefore, the probe light power must be much lower than the pump light power to avoid disturbing the atomic level arrangement.

[0022] The control unit modulates the saturated absorption spectrum signal and generates a frequency discrimination error signal. After passing through the PID control circuit, it outputs a correction signal to the first laser, controlling the first laser to lock its output laser frequency to the atomic transition frequency of cesium atoms in the detection channel to the first excited state. In this embodiment, the saturated absorption spectrum signal is ultimately converted into voltage waveform data and output to the control unit. The frequency discriminator in the control unit performs frequency discrimination processing on the voltage waveform data, generates frequency discrimination data, and inputs the frequency discrimination data as an error input value to the PID control unit. The PID control unit generates a laser power adjustment signal based on the error input value and outputs it to the first laser. The laser power adjustment signal is a correction signal formed by the superposition of the offset voltage signal and the triangular wave signal.

[0023] Preferably, the quantum signal generation module is communicatively connected to the laser control module. Near-infrared laser emitted from the laser control module is incident on the quantum signal generation module. After converting the near-infrared laser into ultraviolet laser, the quantum signal generation module generates polarization-orthogonally correlated photon pairs in the nonlinear crystal through spontaneous parametric down-conversion (SPDC). The quantum signal generation module includes a frequency doubling unit and an integrated optical path unit. The frequency doubling unit is connected to the frequency stabilization unit via optical fiber, and the integrated optical path unit is connected to the frequency doubling unit via optical fiber. The frequency doubling module is used to convert 852nm vertically polarized light into 426nm vertically polarized ultraviolet light, avoiding correlation degradation caused by polarization crosstalk during SPDC, and is directly coupled to the integrated optical path module.

[0024] An integrated optical path unit is used to efficiently convert the input 426nm pump light into polarization orthogonally correlated photon pairs with wavelengths of 852nm. The internal structure enables dual-channel spatial separation, providing a quantum-pure and precisely controllable correlated photon source for Rydberg atom sensing. The near-infrared laser with a frequency of 852nm emitted from the frequency stabilization unit is split into vertically polarized light by the first polarization beam splitter 10 and then incident on the frequency doubling unit. The frequency doubling unit converts the near-infrared laser into ultraviolet laser with a wavelength of 426nm by using a periodically polarized nonlinear crystal and controlling the crystal temperature at the phase matching point. In this embodiment, the nonlinear crystal in the frequency doubling unit is PPKTP (Periodically Poled Potassium Titanyl Phosphate). The 426nm ultraviolet light is still vertically polarized light, and its wavelength is half that of the input 852nm laser.

[0025] The ultraviolet laser emitted from the frequency doubling unit is incident on the integrated optical path unit, triggering the spontaneous parametric downconversion module in the nonlinear crystal and generating polarization orthogonally correlated photon pairs with horizontal and vertical polarization states. The wavelength of the polarization orthogonally correlated photon pairs is 852 nm, which matches the transition line of cesium atoms from the ground state to the first excited state in the probe optical channel.

[0026] The Rydberg atom preparation system is communicatively connected to the correlated photon source component. The correlated photon pair emitted from the correlated photon source component is incident on the Rydberg atom preparation system. The Rydberg atom preparation system forms a dual-wavelength laser field by one polarized correlated photon and one coupled light in the correlated photon pair. The dual-wavelength laser field interacts with the energy level of cesium atoms to prepare Rydberg atoms. Then, after receiving the electromagnetic wave signal incident along the direction of the polarized correlated photon, it outputs an EIT-AT split transmission spectrum signal carrying photon quantity information and a reference light signal.

[0027] Specifically, the Rydberg atom preparation system includes a probe optical channel and a reference optical channel. Both the probe optical channel and the reference optical channel are optically connected to the quantum signal generation module. The probe optical channel includes a microwave resonant cavity 1 with a built-in cesium atom gas cell 3 and a dichroic mirror 2. The microwave resonant cavity 1 is connected to the integrated optical path unit via an optical fiber, and the dichroic mirror 2 is connected to the microwave resonant cavity 1 via an optical fiber; the reference optical channel includes a second reflector 6 connected to a second polarizing beam splitter 4 via an optical fiber.

[0028] As attached Figure 3 As shown, the polarized orthogonally correlated photon pairs emitted from the integrated optical path unit are reflected by the first reflecting mirror 9 and then incident on the Rydberg atom preparation system. The vertically polarized correlated photons |V> separated by the second polarizing beam splitter 4 are incident on the cesium atom gas chamber 3. The cesium atoms in the cesium atom gas chamber 3 change from the ground state (6S) 1 / 2 Transition to the first excited state (6P) 3 / 2A frequency-locked 509nm coupled light beam, after being reflected by dichroic mirror 2, is incident on the cesium atom gas cell 3 in the direction opposite to the vertically polarized correlated photon |V>. The cesium atoms in the cesium atom gas cell 3 then change from the first excited state (6P) to the first excited state (6P). 3 / 2 The cesium atom gas cell 3 receives electromagnetic wave signal 5 incident in the same direction as the vertically polarized correlated photon |V>. The Autler-Townes (AT) splitting effect occurs in the cesium atom gas cell 3, and then the EIT-AT splitting transmission spectrum signal carrying the photon quantity information is transmitted to the correlated detection component through the dichroic mirror 2.

[0029] Within the reference optical channel, a beam of horizontally polarized correlated photons |H>, split from the pair of orthogonally polarized correlated photons emitted by the quantum signal generation module, is reflected by the second mirror 6 and output to the correlated detection component.

[0030] The correlation detection component is communicatively connected to the Rydberg atom preparation system. It performs coincidence counting on the received horizontally polarized correlated photons |H> (reference photons) and coincidence counting on the transmitted photons |V> (transmitted photons). If the difference between the arrival time of the reference photon and the arrival time of the transmitted photon is less than a preset value, a coincidence event is confirmed, the coincidence event is counted, and the coincidence count is output. In this embodiment, the correlation detection component includes a detection module, a timestamp module, and a coincidence determination module.

[0031] The detection module includes a first photon detection unit 7 connected to the detection optical channel and a second photon detection unit 8 connected to the reference optical channel. The EIT-AT split transmission spectrum signal emitted from the detection optical channel, i.e., the vertically polarized correlated photon |V>, is incident on the first photon detection unit, which converts the vertically polarized photon of the EIT-AT split transmission spectrum signal into a first electric pulse. The reference optical signal emitted from the reference optical channel, i.e., the horizontally polarized correlated photon |H>, is incident on the second photon detection unit, which converts the horizontally polarized photon in the reference optical signal into a second electric pulse.

[0032] Preferably, both the first photon detection unit and the second photon detection unit are single-photon detectors, mainly used to detect atomically modulated 852nm transmitted photons and unmodulated correlated photons; the 852nm transmitted photons and correlated photons are converted at the moment of arrival and output as a first electrical pulse and a second electrical pulse, respectively.

[0033] A timestamp module, communicatively connected to the detection module, is used to time-stamp the arrival times of the first and second electrical pulses. In this embodiment, the timestamp module is a time-to-digital converter, used to receive the first and second electrical pulses, convert their arrival times into digital signals, and output them to the compliance determination module. Preferably, in this embodiment, the first and second electrical pulses are respectively multiplied by the number of transition nodes in the delay chain and the time resolution to obtain two timestamp information channels, which are then sent to the compliance determination module.

[0034] A conformity determination module, communicatively connected to a timestamp module, is used to determine the time difference between the arrival times of the first and second electrical pulses. If the time difference is within a preset range, it is confirmed as a conformity event, and the conformity event is counted, outputting the conformity count. Preferably, in this embodiment, the conformity determination module first sets a preset value for a time window, then receives two timestamps and calculates the difference between them. It then compares the difference with the preset value of the time window. If the difference is within the preset range of the time window, it is confirmed as a conformity event, and the conformity event is counted, outputting the conformity count.

[0035] In this embodiment, in the absence of microwaves, within the probe light channel, the highly transmissive probe light in a vertically polarized state penetrates the cesium atom gas cell and propagates in the opposite direction to the horizontally coupled light, thereby inducing the EIT effect (electromagnetic induction transparency). Meanwhile, within the reference light channel, the horizontally polarized reference light propagates stably. The two link photons arrive synchronously at the associated detection component. The first and second electrical pulses are output by the first photon detection unit and the second photon detection unit within the associated detection component, respectively, as shown in the attached diagram. Figure 4 a and Figure 4 As shown in Figure b, it can be seen that due to the aforementioned EIT effect, the arrival time of the first electrical pulse is significantly delayed compared to the arrival time of the second electrical pulse; as shown in the attached figure. Figure 4 As shown in c and 4d, without microwaves, the photon number of the vertically polarized probe light exhibits a single-peak Gaussian distribution, reflecting the atomic resonance transmission characteristics under the EIT effect; without microwaves, the photon number of the horizontally polarized reference light, serving as the system stability benchmark, shows a horizontal straight line, verifying that the reference channel is not affected by atomic interactions. (See attached diagram) Figure 4 As shown in e, in the compliance count statistics output by the compliance determination module, relative to... Figure 4 c. The consistent single-peak shape effectively suppresses background noise.

[0036] In this embodiment, when a microwave scene is present, the microwave frequency and electric field strength are first set. Within the probe light channel, when the microwave signal is input to the cesium atom gas cell, the Autler-Townes (AT) splitting effect occurs, causing the probe light to be absorbed by the atoms and disrupting the correlation of photon pairs, as shown in the attached diagram. Figure 5 As shown in a and 5b, relative to Figure 4 The first pulse signal shown in a Figure 5 The latter half of the first pulse signal shown in a disappears, while Figure 5 The second pulse signal shown in b remains unchanged, correspondingly as shown in the attached diagram. Figure 5 As shown in Figure c, due to the aforementioned AT splitting effect, the photon number of the vertically polarized probe light, which previously exhibited a single-peak Gaussian distribution, splits into two peaks, allowing the splitting distance between the two peaks to be directly obtained. In the presence of microwaves, as shown in the attached figure... Figure 5 As shown in Figure d, the photon count of the reference light in the horizontal polarization state serves as the system stability benchmark and forms a horizontal straight line; as shown in the attached figure. Figure 5 As shown in Figure e, the coincidence count of correlated photon pairs is performed by the coincidence determination module, and the minimum change in the coincidence count is obtained under a fixed signal-to-noise ratio. Furthermore, it can be seen that the coincidence count of photon pairs located at the trough is relatively... Figure 5 The photon count in c, located at the trough, shows a decrease; this aligns with the overall bimodal pattern of the count statistics. Figure 5 The bimodal shape in c remains consistent.

[0037] In this embodiment, the electric field intensity of the microwave signal is obtained by multiplying Planck's constant by the splitting distance between the two peaks and then dividing by the dipole moment of the Rydberg state of the cesium atom. Simultaneously, the detection sensitivity is obtained based on Planck's constant, the minimum change in coincidence count under a fixed signal-to-noise ratio, and the dipole moment of the Rydberg state of the cesium atom. Therefore, the Rydberg atom electromagnetic signal detection device based on correlated photon coincidence measurement described in this embodiment generates orthogonally polarized correlated photon pairs from a single-polarized laser using a correlated photon source component. The Rydberg atom preparation system forms a dual-wavelength laser field by combining one polarized correlated photon from the correlated photon pair with a coupled light source. The dual-wavelength laser field interacts with the energy levels of the cesium atom to prepare Rydberg atoms. Then, after receiving the electromagnetic wave signal incident along the polarized correlated photon direction, it outputs the EIT-AT split transmission spectrum signal and a reference light signal to the correlated detection component. Finally, the correlated detection component performs coincidence counting on the correlated photon pairs to achieve the detection of electromagnetic signals such as microwaves and improves the electric field sensitivity.

Claims

1. A Rydberg atom electromagnetic signal detection device based on correlated photon coincidence measurement, characterized in that, The application relates to a quantum communication system, which comprises the following components: a correlated photon source assembly, which is used for generating a polarized-orthogonal correlated photon pair from single-polarization and frequency-stable laser; a Rydberg atom preparation system, which is connected with the correlated photon source assembly, and the correlated photon pair emitted from the correlated photon source assembly is incident to the Rydberg atom preparation system; the Rydberg atom preparation system forms a dual-wavelength laser field by using one of the correlated photon pairs and one coupled light, the dual-wavelength laser field interacts with cesium atom energy levels to prepare a Rydberg atom, and then, after receiving an electromagnetic wave signal incident along the direction of the polarized correlated photon, the Rydberg atom preparation system outputs an EIT-AT split transmission spectrum signal carrying photon quantity information and a reference light signal; a correlated detection assembly, which is connected with the Rydberg atom preparation system, and is used for counting reference photons of the received reference light signal and counting transmission photons of the EIT-AT split transmission spectrum signal; if the difference between the arrival time of the reference photon and the arrival time of the transmission photon is within a preset range, the difference is regarded as a coincidence event and a coincidence count is recorded.

2. The Rydberg atom electromagnetic signal probing apparatus based on correlated photon coincidence measurement of claim 1, wherein, The correlated photon source assembly comprises: a laser control module, which is used for stabilizing and controlling the laser frequency and outputting the frequency-stabilized near-infrared laser; a quantum signal generation module, which is connected with the laser control module, and the near-infrared laser emitted from the laser control module is incident to the quantum signal generation module; the quantum signal generation module converts the near-infrared laser into ultraviolet laser, and then generates the polarized-orthogonal correlated photon pair in a nonlinear crystal through a spontaneous parametric down-conversion method.

3. The Rydberg atom electromagnetic signal probing apparatus based on correlated photon coincidence measurement of claim 1 or 2, wherein, The Rydberg atom preparation system comprises: a detection light channel, which is connected with the quantum signal generation module, and a vertical polarized light beam split from the polarized-orthogonal correlated photon pair emitted from the quantum signal generation module is used as detection light; after the vertical polarized light beam is parallelly incident to a coupled light beam in the detection light channel, alkali metal atoms in the detection light channel are transitioned from a ground state to a Rydberg state; after a microwave signal is incident to the inside of the detection light channel in the parallel direction of the detection light, the detection light channel outputs an EIT-AT split transmission spectrum signal carrying information; a reference light channel, which is connected with the quantum signal generation module, and a horizontal polarized light beam split from the polarized-orthogonal correlated photon pair emitted from the quantum signal generation module is used as reference light and output through the reference light channel.

4. The Rydberg atom electromagnetic signal probing apparatus based on correlated photon coincidence measurement of claim 3, wherein, The correlated detection assembly comprises: a detection module, which comprises a first photon detection unit connected with the detection light channel and a second photon detection unit connected with the reference light channel; the EIT-AT split transmission spectrum signal emitted from the detection light channel is incident to the first photon detection unit, the first photon detection unit converts the vertical polarized photons of the EIT-AT split transmission spectrum signal into a first electric pulse, and the reference light signal emitted from the reference light channel is incident to the second photon detection unit, the second photon detection unit converts the horizontal polarized photons in the reference light signal into a second electric pulse. A timestamp module, which is in communication connection with the single-photon detection module, is configured to time mark the arrival time of the first electric pulse and the arrival time of the second electric pulse; A coincidence determination module, which is in communication connection with the timestamp module, is configured to determine the time difference between the first electric pulse arrival time and the second electric pulse arrival time, and when the time difference is within a preset range, a coincidence event is confirmed, and a coincidence count is output.

5. The Rydberg atom electromagnetic signal probing apparatus based on correlated photon coincidence measurement of claim 2, wherein, The laser control module comprises: A first laser for generating near-infrared laser with a wavelength of 852 nm; A frequency stabilization unit, which is connected with the first laser through an optical fiber, and the 852 nm near-infrared laser emitted by the first laser is incident to a third polarization beam splitter inside the frequency stabilization unit. The third polarization beam splitter splits the near-infrared laser into a small-power detection light incident to a cesium atomic cell, and a large-power pump light incident to the cesium atomic cell in the opposite direction of the small-power detection light after being reflected by a plurality of third mirrors. The cesium atomic cell emits a saturated absorption spectrum signal; A control unit, which is in communication connection with the frequency stabilization unit and the first laser, is configured to modulate the saturated absorption spectrum signal and generate a frequency discrimination error signal, and output a correction signal to the first laser after a PID control circuit to control the first laser to lock the output laser frequency to the atomic transition frequency of the alkali metal atom transition to the first excited state in the detection channel.

6. The Rydberg atom electromagnetic signal probing apparatus based on correlated photon coincidence measurement of claim 2, wherein, The quantum signal generation module comprises: A frequency doubling unit, which is connected with the frequency stabilization unit through an optical fiber, and the near-infrared laser with a wavelength of 852 nm emitted by the frequency stabilization unit is incident to the frequency doubling unit after being split by a first polarization beam splitter. The frequency doubling unit converts the near-infrared laser into ultraviolet laser with a wavelength of 426 nm by a periodically poled nonlinear crystal and controlling the temperature at a phase matching point, wherein the temperature range at the phase matching point is 190℃ to 210℃; An integrated optical path unit, which is connected with the frequency doubling unit through an optical fiber, and the ultraviolet laser emitted by the frequency doubling unit is incident to the integrated optical path unit. The integrated optical path unit generates a polarization orthogonal correlated photon pair in a nonlinear crystal by spontaneous parametric down-conversion, and outputs the polarization orthogonal correlated photon pair in horizontal and vertical polarization directions by a double-channel spatial separation, wherein the wavelength of the polarization orthogonal correlated photon pair matches the transition line from the ground state to the first excited state of the cesium atom in the detection light channel.

7. The Rydberg atom electromagnetic signal probing apparatus based on correlated photon coincidence measurement of claim 3, wherein, The detection light channel comprises: The microwave resonant cavity with cesium atom gas chamber is connected with the integrated optical path unit through an optical fiber, a polarization orthogonal correlated photon pair emitted from the integrated optical path unit is incident to a polarization correlated photon in a vertical polarization state which is split by a second polarization beam splitter, and cesium atoms in the cesium atom gas chamber are transitioned from a ground state (6S 1 / 2 ) to a first excited state (6P 3 / 2 ). A dichroic mirror is connected with a microwave resonance cavity through an optical fiber, a bundle of frequency-locked coupled light is reflected by the dichroic mirror and then is incident to a cesium atom cell in the opposite direction of the polarization correlation photon, and then the cesium atoms in the cesium atom cell are transitioned from a first excited state (6P 3 / 2 ) to a Rydberg state with a principal quantum number greater than or equal to 50; the cesium atom cell receives an electromagnetic wave signal incident in the same direction as the polarization correlation photon, and the EIT-AT split transmission spectrum signal carrying information is transmitted out through the dichroic mirror.

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