A Laser Frequency Stabilization Method Applied to a Rydberg Atom Detection System

Abstract

The present application relates to a laser frequency stabilization method applied to a Rydberg atom detection system. The method includes: the laser frequency stabilization device includes a detection laser frequency stabilization unit and a coupling laser frequency stabilization unit. A modulated detection laser and a modulation signal are output from the detection laser frequency stabilization unit to the coupling laser frequency stabilization unit to achieve the frequency stabilization of the coupling laser frequency stabilization unit. Among them, a modulated detection laser is separated from the saturated absorption spectrum of the detection laser frequency stabilization unit and acts together with the coupling laser to generate a Rydberg EIT spectrum. At the same time, the saturated absorption spectrum signal and the Rydberg EIT spectrum signal are mixed with the modulation signal generated by the signal source to generate respective phase discrimination signals, which are respectively used for the frequency stabilization of the detection laser and the coupling laser. The present invention can achieve the frequency stabilization of the detection laser and the coupling laser at room temperature by only using one signal source and laser modulation device, with good frequency stabilization effect, and reduces the cost and complexity of the entire frequency stabilization system.

Description

Technical Field

[0001] This application relates to the technical field of laser frequency stabilization, and particularly to a laser frequency stabilization method applied to a Rydberg atom detection system. Background Technique

[0002] A Rydberg atom refers to a highly excited atom with the principal quantum number n much greater than 1, and its radiative lifetime is proportional to n 3 in direct proportion, the electric dipole moment is proportional to n 4 in direct proportion, and the polarizability is proportional to n 7 in direct proportion. These characteristics make Rydberg atoms an excellent physical platform for researching fields such as quantum storage, quantum computing, and quantum precision measurement.

[0003] Three-level ladder-type electromagnetically induced transparency (EIT) is one of the most widely used Rydberg atom detection means. A weak probe light excites alkali metal atoms from the ground state to an intermediate state, and at the same time, a strong coupling light excites the atoms from the intermediate state to the required Rydberg state. Locking the laser frequency to the corresponding atomic transition energy level is crucial for achieving precise measurement of Rydberg atoms.

[0004] In the prior art, laser frequency stabilization methods can be divided into two categories: one is the PDH (Pound–Drever–Hall) frequency locking method based on an ultrastable cavity; the other is the frequency locking method based on atomic transition spectroscopy. The PDH frequency locking method does not rely on an external frequency reference and does not require adding low-frequency perturbations to the laser frequency. Moreover, the signal-to-noise ratio of the phase-locking curve of this method is very high, and the laser linewidth can be narrowed. However, this method requires extremely high mechanical and temperature stability, and requires additional means to shift the laser frequency to the atomic transition. The frequency locking method based on atomic transition spectroscopy can accurately lock the laser frequency to the atomic transition frequency, has lower requirements for the external experimental environment, and is more likely to achieve practical application and miniaturization of the laser frequency stabilization system. For example, Jiao Yuechun et al. disclosed a laser frequency stabilization method based on Rydberg EIT (Jiao Y, Li J, Wang L, et al. Laser frequency locking based on Rydberg electromagnetically induced transparency [J]. Chinese Physics B: English Edition, 2016 (5): 3.). This method obtains the phase-comparison signal by modulating the piezoelectric ceramic voltage of the detection laser. The optical path is simple, but the modulated detection light will broaden the laser linewidth, affecting the measurement accuracy of the Rydberg atom. Jia Fengdong et al. disclosed a Rydberg laser frequency stabilization method using Zeeman modulation (Jia F, Zhang J, Zhang L, et al. Frequency Stabilization Method for Transition to Rydberg State using Zeeman Modulation [J]. Applied Optics, 2020, 59 (7).). This method uses the Zeeman effect to modulate the three-level stepped Rydberg EIT energy level to lock the detection light and the coupling light, but the entire frequency stabilization system requires two magnetic field coils to modulate the detection light and the coupling light respectively, which increases the complexity of the system. Both of the above methods modulate the detection light and the coupling light separately, which increases the cost and complexity of the entire frequency stabilization system, limiting its application in practical engineering. Summary of the Invention

[0005] Based on this, it is necessary to provide a laser frequency stabilization method and device for a Rydberg atomic detection system that can reduce system complexity in order to address the above technical problems.

[0006] A laser frequency stabilization method applied to a Rydberg atomic detection system, the method comprising:

[0007] Building a detection laser frequency stabilization unit, and achieving frequency stabilization of the detection laser through the detection laser frequency stabilization unit;

[0008] Build a coupled laser frequency stabilization unit; the coupled laser frequency stabilization unit includes an EIT spectral unit and a coupled light phase discrimination feedback unit;

[0009] Output a modulated probe laser through the saturated absorption spectral unit in the probe laser frequency stabilization unit, and input the frequency-stabilized modulated probe laser into the EIT spectral unit to generate an EIT spectral signal;

[0010] Output a modulation signal through the probe light phase discrimination feedback unit in the probe laser frequency stabilization unit, perform mixing through the coupled light phase discrimination feedback unit according to the EIT spectral signal and the modulation signal to obtain a phase discrimination signal at the target position of the coupled laser, and achieve the frequency stabilization of the coupled laser through the phase discrimination signal at the target position of the coupled laser.

[0011] In one embodiment, it further includes: building a probe laser frequency stabilization unit; the probe laser frequency stabilization unit includes a probe laser generating device, a probe beam splitting unit, a saturated absorption spectral unit, a first photodetector, and a probe light phase discrimination feedback unit;

[0012] Emit a probe laser through the probe laser generating device, and obtain a probe laser for frequency stabilization through the probe beam splitting unit;

[0013] Generate a saturated absorption spectral signal according to the probe laser for frequency stabilization through the saturated absorption spectral unit;

[0014] Convert the saturated absorption spectral signal into an electrical signal through the first photodetector as a reference signal to generate a phase discrimination signal of the probe laser in the probe light phase discrimination feedback unit;

[0015] Real-time feedback the phase discrimination signal voltage of the probe laser to the probe laser generating device to achieve the frequency stabilization of the probe laser.

[0016] In one embodiment, it further includes: building a coupled laser frequency stabilization unit; the coupled laser frequency stabilization unit includes a coupled laser generating device, a coupled beam splitting unit, an EIT spectral unit, a second photodetector, and a coupled light phase discrimination feedback unit.

[0017] In one embodiment, it further includes: emit a coupled laser through the coupled laser generating device, obtain a coupled laser for frequency stabilization through the coupled beam splitting unit, and input it into the EIT spectral unit;

[0018] Output a modulated probe laser through the saturated absorption spectral unit in the probe laser frequency stabilization unit, and input the frequency-stabilized modulated probe laser into the EIT spectral unit;

[0019] The EIT spectrum unit generates an EIT spectrum signal based on the frequency-stabilized coupling laser and the modulated probe laser.

[0020] In one embodiment, it further includes: converting the EIT spectrum signal into an electrical signal through the second photodetector as a reference signal;

[0021] An FM signal is output through the probe light phase discrimination feedback unit in the probe laser frequency stabilization unit;

[0022] A phase discrimination signal of the coupling laser is generated in the coupling light phase discrimination feedback unit according to the reference signal and the FM signal.

[0023] In one embodiment, it further includes: the phase discrimination signal voltage at the target position of the coupling laser is fed back to the coupling laser generating device in real time to achieve frequency stabilization of the coupling laser.

[0024] In one embodiment, it further includes: the laser frequency of the probe laser frequency stabilization unit is stabilized at the transition frequency from the ground state to the intermediate state of the alkali metal atom; the laser frequency of the coupling laser frequency stabilization unit is stabilized at the transition frequency from the intermediate state of the alkali metal atom to the preset Rydberg state.

[0025] In one embodiment, it further includes: the probe beam splitting unit is further used to obtain the experimental probe laser, and the power ratio between the experimental probe laser and the frequency-stabilized probe laser can be adjusted by the probe beam splitting unit.

[0026] In one embodiment, it further includes: the coupling beam splitting unit is further used to obtain the experimental coupling laser, and the power ratio between the experimental coupling laser and the frequency-stabilized coupling laser can be adjusted by the coupling beam splitting unit.

[0027] A laser frequency stabilization device applied to a Rydberg atom detection system, the device includes:

[0028] A probe laser frequency stabilization unit and a coupling laser frequency stabilization unit;

[0029] The probe laser frequency stabilization unit includes a saturation absorption spectrum unit and a probe light phase discrimination feedback unit;

[0030] The coupling laser frequency stabilization unit includes an EIT spectrum unit and a coupling light phase discrimination feedback unit;

[0031] The saturation absorption spectrum unit is used to output a modulated probe laser, and after frequency stabilization, it is input into the EIT spectrum unit;

[0032] The EIT spectrum unit is used to generate an EIT spectrum signal;

[0033] The detection light phase discrimination feedback unit is used to output a modulation signal;

[0034] The coupled light phase discrimination feedback unit is used to mix the EIT spectral signal and the modulation signal to obtain a phase discrimination signal at the position of the coupled laser target, so as to realize the frequency stabilization of the coupled laser.

[0035] The above laser frequency stabilization method and device applied to the Rydberg atom detection system, the laser frequency stabilization device includes a detection laser frequency stabilization unit and a coupled laser frequency stabilization unit, and a modulated detection laser and a modulation signal are output from the detection laser frequency stabilization unit to the coupled laser frequency stabilization unit to realize the frequency stabilization of the coupled laser frequency stabilization unit. Among them, in the saturation absorption spectrum of the detection laser frequency stabilization unit, a modulated detection laser is separated to act together with the coupled laser to generate a Rydberg EIT spectrum. At the same time, the saturation absorption spectrum signal and the Rydberg EIT spectrum signal are mixed with the modulation signal generated by the signal source to generate respective phase discrimination signals for the frequency stabilization of the detection laser and the coupled laser. The present invention can realize the frequency stabilization of the detection laser and the coupled laser only by using one signal source and laser modulation device at room temperature, has a good frequency stabilization effect, and reduces the cost and complexity of the entire frequency stabilization system. Description of the Drawings

[0036] Figure 1 It is a schematic flow chart of a laser frequency stabilization method applied to a Rydberg atom detection system in an embodiment;

[0037] Figure 2 It is a schematic structural diagram of a laser frequency stabilization device applied to a Rydberg atom detection system in an embodiment;

[0038] Figure 3 It is a schematic structural diagram of a laser frequency stabilization device applied to a Rydberg atom detection system in a specific embodiment;

[0039] Figure 4 It is a result diagram of the saturation absorption spectrum and the detection light phase discrimination curve in a specific embodiment of the laser frequency stabilization technology applied to the Rydberg atom detection system provided by the present invention;

[0040] Figure 5 It is a result diagram of the EIT spectrum and the coupled light phase discrimination curve in a specific embodiment of the laser frequency stabilization technology applied to the Rydberg atom detection system provided by the present invention;

[0041] Figure 6 It is a comparison diagram of the detection light frequency before and after frequency stabilization in a specific embodiment of the laser frequency stabilization technology applied to the Rydberg atom detection system provided by the present invention;

[0042] Figure 7It is a comparison diagram before and after the frequency stabilization of the coupling light in a specific embodiment of the laser frequency stabilization technology applied to the Rydberg atom detection system provided by the present invention. Detailed implementation manners

[0043] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0044] In one embodiment, as Figure 1 shown, a laser frequency stabilization method applied to a Rydberg atom detection system is provided, including the following steps:

[0045] Step 102, build a detection laser frequency stabilization unit to achieve the frequency stabilization of the detection laser through the detection laser frequency stabilization unit.

[0046] The existing detection laser frequency stabilization technology is relatively mature, but there is less research on the coupling laser frequency stabilization. In order to reduce the complexity and system cost of the laser frequency stabilization device applied to the Rydberg atom detection system, the present invention proposes to establish the association between the detection laser frequency stabilization unit and the coupling laser frequency stabilization unit on the basis of the detection laser frequency stabilization unit to achieve the frequency stabilization of the coupling laser frequency stabilization unit.

[0047] Step 104, build a coupling laser frequency stabilization unit.

[0048] The coupling laser frequency stabilization unit includes an EIT spectroscopy unit and a coupling light phase discrimination feedback unit.

[0049] Step 106, output a modulated detection laser through the saturation absorption spectroscopy unit in the detection laser frequency stabilization unit, and input the frequency-stabilized modulated detection laser into the EIT spectroscopy unit to generate an EIT spectroscopy signal.

[0050] One of the technical means of the present invention is to separate a modulated detection laser from the saturation absorption spectrum and act together with the coupling laser to generate a Rydberg EIT spectrum.

[0051] Step 108, output a modulation signal through the detection light phase discrimination feedback unit in the detection laser frequency stabilization unit, mix the EIT spectroscopy signal and the modulation signal through the coupling light phase discrimination feedback unit to obtain a phase discrimination signal at the target position of the coupling laser, and achieve the frequency stabilization of the coupling laser through the phase discrimination signal at the target position of the coupling laser.

[0052] On the other hand, the detection laser frequency stabilization unit also outputs a modulation signal to the coupling laser frequency stabilization unit. The Rydberg EIT spectroscopy signal generates a phase discrimination signal through mixing with the modulation signal generated by the signal source for the frequency stabilization of the coupling laser.

[0053] In the above laser frequency stabilization method applied to the Rydberg atom detection system, the laser frequency stabilization device includes a detection laser frequency stabilization unit and a coupling laser frequency stabilization unit. A modulated detection laser and a modulation signal are output from the detection laser frequency stabilization unit to the coupling laser frequency stabilization unit to achieve the frequency stabilization of the coupling laser frequency stabilization unit. Among them, a modulated detection laser is separated from the saturated absorption spectrum of the detection laser frequency stabilization unit and acts together with the coupling laser to generate a Rydberg EIT spectrum. At the same time, the saturated absorption spectrum signal and the Rydberg EIT spectrum signal are mixed with the modulation signal generated by the signal source to generate respective phase discrimination signals, which are respectively used for the frequency stabilization of the detection laser and the coupling laser. In the present invention, at room temperature, only one signal source and laser modulation device are used to achieve the frequency stabilization of the detection laser and the coupling laser, with good frequency stabilization effect, and the cost and complexity of the entire frequency stabilization system are reduced.

[0054] In one of the embodiments, as Figure 2 shown, a laser frequency stabilization device 10 applied to the Rydberg atom detection system is provided, including a detection laser frequency stabilization unit 11 and a coupling laser frequency stabilization unit 12. It is characterized in that the detection laser frequency stabilization unit 11 outputs a modulated detection laser 1131 and a modulation signal 1152 to the coupling laser frequency stabilization unit 12. The technical path is to first stabilize the frequency of the detection laser and then stabilize the frequency of the coupling laser.

[0055] The detection laser frequency stabilization unit 11 includes a detection laser generating device 111, a detection light beam splitting unit 112, a saturated absorption spectrum unit 113, a photodetector 114, and a detection light phase discrimination feedback unit 115. The modulated detection laser generates a saturated absorption spectrum signal in the saturated absorption spectrum unit 113. The saturated absorption spectrum signal is converted into an electrical signal by the photodetector 114 and used as a reference signal to generate a phase discrimination signal in the detection light phase discrimination feedback unit 115. The phase discrimination signal voltage at the target position of the detection laser is fed back to the detection laser generating device 111 in real time to achieve the frequency stabilization of the detection laser.

[0056] Specifically, the detection laser generating device 111 generates a detection laser 1111. The detection laser 1111 is divided by the detection light beam splitting unit 112 into an experimental detection laser 1121 and a frequency stabilization detection laser 1122, and the detection light beam splitting unit 112 can adjust the power ratio between the experimental detection laser 1121 and the frequency stabilization detection laser 1122. The frequency stabilization detection laser 1122 is input into the saturated absorption spectroscopy unit 113 to generate a saturated absorption spectrum. The saturated absorption spectroscopy unit 113 generates a modulated detection laser under the action of the modulation signal 1151 input by the detection light phase discrimination feedback unit 115. A part of the modulated detection laser 1131 is input into the EIT spectroscopy unit 123 for coupling light frequency stabilization. The output optical signal 1132 of the saturated absorption spectroscopy unit 113 is converted into an electrical signal 1141 by the photodetector 114, and the electrical signal 1141 is input into the detection light phase discrimination feedback unit 115 to generate a detection light phase discrimination feedback signal 1153. At the same time, the detection light phase discrimination feedback unit 115 generates another modulation signal 1152 and inputs it into the coupling light phase discrimination feedback unit 125 for coupling light frequency stabilization. The detection light phase discrimination feedback signal 1153 acts on the piezoelectric ceramic voltage of the detection laser generating device 111 to stabilize the detection laser frequency at the transition frequency from the ground state to the intermediate state of the alkali metal atom.

[0057] The coupling laser frequency stabilization unit 12 includes a coupling laser generating device 121, a coupling light beam splitting unit 122, an EIT spectroscopy unit 123, a photodetector 124, and a coupling light phase discrimination feedback unit 125. The frequency-stabilized modulated detection laser and the coupling laser generate an EIT spectral signal in the EIT spectroscopy unit 123. The EIT spectral signal is converted into an electrical signal by the photodetector 124 and used as a reference signal to generate a phase discrimination signal in the coupling light phase discrimination feedback unit 125. The phase discrimination signal voltage at the target position of the coupling laser is fed back to the coupling laser generating device 121 in real time to achieve the frequency stabilization of the coupling laser.

[0058] Specifically, the coupled laser generating device 121 generates a coupled laser 1211. The coupled laser 1211 is divided by the coupled light beam splitting unit 122 into an experimental coupled laser 1221 and a frequency stabilization coupled laser 1222, and the coupled light beam splitting unit 122 can adjust the power ratio between the experimental coupled laser 1221 and the frequency stabilization coupled laser 1222. The frequency stabilization coupled laser 1222 and the modulated probe laser 1131 act together on the EIT spectral unit 123 to generate a Rydberg EIT spectrum. The output optical signal 1232 of the EIT spectral unit 123 is converted into an electrical signal 1241 by the photodetector 124, and the electrical signal 1241 and the modulation signal 1152 act together on the coupled optical phase discrimination feedback unit 125 to generate a coupled optical phase discrimination feedback signal 1253. The coupled optical phase discrimination feedback signal 1253 acts on the piezoelectric ceramic voltage of the coupled laser generating device 121 to stabilize the coupled laser frequency at the transition frequency from the intermediate state of the alkali metal atom to the desired Rydberg state.

[0059] In another specific embodiment, as Figure 3 shown, a schematic structural diagram of a laser frequency stabilization device applied to a Rydberg atom detection system is provided. The laser frequency stabilization device 20 applied to the Rydberg atom detection system includes a probe laser frequency stabilization device 21 and a coupled laser frequency stabilization device 22.

[0060] Specifically, the probe laser phase discrimination feedback device 215 controls the piezoelectric ceramic voltage of the 852 nm laser to generate a beam of laser with a frequency scanning range covering the cesium atom ground state (6S 1 / 2 , F = 4) to the intermediate state (6P 3 / 2, the probe laser 2111 for detecting the transition frequency of (6S 1 / 2 , F = 4) to (6P 3 / 2 , F’=5). The probe laser 2111 is split by a probe light splitting device 212 composed of a half-wave plate 2121 and a polarization beam splitting prism 2122 into an experimental probe laser 2123 and a frequency stabilization probe laser 2124. Further, by changing the angle between the fast axis or slow axis of the half-wave plate 2121 and the polarization direction of the probe laser 2111, the power ratio between the experimental probe laser 2123 and the frequency stabilization probe laser 2124 can be changed. The frequency stabilization probe laser 2124 generates a saturated absorption spectrum signal 2136 in the saturated absorption spectroscopy device 213. Specifically, after being split by a white glass plate 2131, 4% of the energy of 2124 enters the cesium atomic gas cell 2135, and 96% of the energy of 2124 enters the electro-optic modulator (EOM) 2132 after being reflected by a mirror. A modulation signal with a frequency of 100 kHz and an amplitude of 10 V is generated in the signal source 2152 of the probe laser phase discrimination feedback device 215, and an amplified modulation signal 2157 is generated by a high-voltage amplifier 2151 with a voltage amplification factor of 20 times and acts on the EOM 2132 to modulate the input probe laser. The modulated probe laser 2133 is split into two beams by a beam splitter 2134. One transmitted beam 2137 enters the coupled laser frequency stabilization device 22 to participate in the coupled laser frequency stabilization, and the other reflected beam enters the cesium atomic gas cell 2135 to act together with the unmodulated probe laser to generate a saturated absorption spectrum signal 2136. After passing through the beam splitter 2134, 2136 enters the photodetector 214. The photodetector 214 converts the saturated absorption spectrum signal 2136 into an electrical signal 2141 and inputs it into one input port of the mixer 2154 in the probe laser phase discrimination feedback device 215. Another modulation signal with a frequency of 100 kHz and an amplitude of 2 V is generated in the signal source 2152 of the probe laser phase discrimination feedback device 215, and after being phase-shifted by a phase shifter 2153, it enters the other input port of the mixer 2154. By adjusting the phase shift amount of the phase shifter 2153, the amplitude of the probe light phase discrimination feedback signal 2159 can be changed. The down-converted signal after mixing enters the low-pass filter 2155 from the output port of the mixer 2154 for low-pass filtering and then inputs into the feedback device (PID) 2156. The PID 2156 outputs the probe light phase discrimination feedback signal 2159 to act on the piezoelectric ceramic voltage of the 852 nm laser, so that the probe laser frequency is stabilized at the transition frequency from the ground state (6S 1 / 2 , F = 4) to the intermediate state (6P 3 / 2 , F’=5).

[0061] Further, the coupled laser phase discrimination feedback device 225 controls the piezoelectric ceramic voltage of the 510 nm laser to generate a beam of laser with a frequency scanning range covering the cesium atomic intermediate state (6P 3 / 2, the coupling laser 2211 for the transition frequency to a certain Rydberg state (F’ = 5). The coupling laser 2211 is divided by the coupling light beam splitting device 222 composed of a half-wave plate 2221 and a polarization beam splitting prism 2222 into the experimental coupling laser 2223 and the frequency stabilization coupling laser 2224. Further, by changing the angle between the fast axis or the slow axis of the half-wave plate 2221 and the polarization direction of the coupling laser 2211, the power ratio between the experimental coupling laser 2223 and the frequency stabilization coupling laser 2224 can be changed. The frequency stabilization coupling laser 2224 generates an EIT spectral signal 2232 in the EIT spectral device 223. Specifically, the coupling laser 2224 enters the cesium atomic vapor cell 2233 after being reflected by the dichroic mirror 2231. A modulated probe laser beam 2137 split from the probe laser frequency stabilization device 21 enters the cesium atomic vapor cell 2233 after passing through the attenuation sheet 2234, and jointly acts with the coupling laser to generate the EIT spectral signal 2232. Among them, the attenuation sheet 2234 is used to adjust the power of the probe laser 2137 entering the cesium atomic vapor cell 2233 and thus adjust the spectral width of the EIT spectral signal 2232. The EIT spectral signal 2232 passes through the dichroic mirror 2231 and then enters the photodetector 224. The photodetector 224 converts the EIT spectral signal 2232 into an electrical signal 2241 and inputs it into one input port of the mixer 2252 in the coupling laser phase discrimination feedback device 225. A modulation signal 2158 with a frequency of 100 kHz and an amplitude of 2 V generated in the probe laser frequency stabilization device 21 enters another input port of the mixer 2252 after being phase-shifted by the phase shifter 2251 in the coupling laser phase discrimination feedback device 225. By adjusting the phase shift amount of the phase shifter 2251, the amplitude of the coupling light phase discrimination feedback signal 2255 can be changed. The down-converted signal after mixing enters the low-pass filter 2253 from the output port of the mixer 2252 for low-pass filtering and then inputs into the feedback device (PID) 2254. The coupling light phase discrimination feedback signal 2255 output by 2254 acts on the piezoelectric ceramic voltage of the 510 nm laser, so that the probe laser frequency is stabilized at the transition frequency from the intermediate state (6P 3 / 2 , F’ = 5) to a certain Rydberg state.

[0062] Figure 4 It is the result diagram of the saturated absorption spectrum and the probe light phase discrimination curve of a specific embodiment of the laser frequency stabilization technology applied to the Rydberg atom detection system provided by the present invention. Figure 4 (a) is the cesium atom saturated absorption spectral signal detected by the photodetector. The saturated absorption peak of the transition from the ground state (6S 1 / 2 , F = 4) to the intermediate state (6P 3 / 2 , F’ = 5) is at the 401 frequency. Figure 4 (b) is the corresponding probe light phase discrimination feedback signal. The corresponding probe light phase discrimination feedback signal at the 401 frequency is at the zero point position.

[0063] Figure 5 This is the result diagram of the EIT spectrum and the phase discrimination curve of the coupling light in a specific embodiment of the laser frequency stabilization technology applied to the Rydberg atom detection system provided by the present invention. Figure 5 (a) is the EIT spectrum signal of cesium atoms detected by a photodetector. The EIT transmission peak of the transition from the intermediate state (6P 3 / 2 , F’ = 5) to the Rydberg state (42D 5 / 2 ) of cesium atoms is at the 501 frequency. Figure 5 (b) is the corresponding phase discrimination feedback signal of the coupling light. The corresponding phase discrimination feedback signal of the coupling light is at the zero position at the 501 frequency.

[0064] Figure 6 This is the comparison diagram before and after the frequency stabilization of the probe light in a specific embodiment of the laser frequency stabilization technology applied to the Rydberg atom detection system provided by the present invention. 601 is the frequency change curve of the probe laser when the probe laser frequency stabilization device is not working, and 602 is the frequency change curve of the probe laser after the probe laser frequency stabilization device works.

[0065] Figure 7 This is the comparison diagram before and after the frequency stabilization of the coupling light in a specific embodiment of the laser frequency stabilization technology applied to the Rydberg atom detection system provided by the present invention. 701 is the frequency change curve of the coupling laser when the coupling laser frequency stabilization device is not working, and 702 is the frequency change curve of the coupling laser after the coupling laser frequency stabilization device works.

[0066] It should be understood that although Figure 1 the steps in the flowchart are shown in sequence according to the indication of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise clearly stated in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, Figure 1 at least a part of the steps in

[0067] can include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or sub-steps or stages of other steps.

[0068] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A laser frequency stabilization method applied to a Rydberg atom detection system, characterized in that, The method includes: Construct a frequency stabilization unit for the probing laser, and achieve frequency stabilization of the probing laser through the frequency stabilization unit for the probing laser; Construct a frequency stabilization unit for the coupling laser; the frequency stabilization unit for the coupling laser includes an EIT spectral unit and a coupling light phase discrimination feedback unit; Output a modulated probing laser through the saturated absorption spectral unit in the frequency stabilization unit for the probing laser, and input the frequency-stabilized modulated probing laser into the EIT spectral unit to generate an EIT spectral signal; Output a modulation signal through the probing light phase discrimination feedback unit in the frequency stabilization unit for the probing laser, perform frequency mixing through the coupling light phase discrimination feedback unit according to the EIT spectral signal and the modulation signal to obtain a phase discrimination signal at the target position of the coupling laser, and achieve frequency stabilization of the coupling laser through the phase discrimination signal at the target position of the coupling laser.

2. The method according to claim 1, wherein Construct a frequency stabilization unit for the probing laser, and achieve frequency stabilization of the probing laser through the frequency stabilization unit for the probing laser, including: Construct a frequency stabilization unit for the probing laser; the frequency stabilization unit for the probing laser includes a probing laser generating device, a probing beam splitting unit, a saturated absorption spectral unit, a first photodetector, and a probing light phase discrimination feedback unit; Emit a probing laser through the probing laser generating device, and obtain a probing laser for frequency stabilization through the probing beam splitting unit; Generate a saturated absorption spectral signal according to the probing laser for frequency stabilization through the saturated absorption spectral unit; Convert the saturated absorption spectral signal into an electrical signal through the first photodetector as a reference signal to generate a phase discrimination signal for the probing laser in the probing light phase discrimination feedback unit; Real-time feedback the phase discrimination signal voltage of the probing laser to the probing laser generating device to achieve frequency stabilization of the probing laser.

3. The method according to claim 2, wherein Construct a frequency stabilization unit for the coupling laser; the frequency stabilization unit for the coupling laser includes an EIT spectral unit and a coupling light phase discrimination feedback unit, including: Construct a frequency stabilization unit for the coupling laser; the frequency stabilization unit for the coupling laser includes a coupling laser generating device, a coupling beam splitting unit, an EIT spectral unit, a second photodetector, and a coupling light phase discrimination feedback unit.

4. The method according to claim 3, wherein Output a modulated probing laser through the saturated absorption spectral unit in the frequency stabilization unit for the probing laser, and input the frequency-stabilized modulated probing laser into the EIT spectral unit to generate an EIT spectral signal, including: Emit a coupling laser through the coupling laser generating device, obtain a coupling laser for frequency stabilization through the coupling beam splitting unit, and input it into the EIT spectral unit; Output a modulated probing laser through the saturated absorption spectral unit in the frequency stabilization unit for the probing laser, and input the frequency-stabilized modulated probing laser into the EIT spectral unit; Generate an EIT spectral signal according to the coupling laser for frequency stabilization and the modulated probing laser through the EIT spectral unit.

5. The method according to claim 4, wherein Perform frequency mixing through the coupling light phase discrimination feedback unit according to the EIT spectral signal and the modulation signal to obtain a phase discrimination signal at the target position of the coupling laser, including: Convert the EIT spectral signal into an electrical signal through the second photodetector as a reference signal; Output a modulation signal through the detection light phase discrimination feedback unit in the detection laser frequency stabilization unit; A phase detection signal of the coupled laser is generated in the coupled optical phase detection feedback unit according to the reference signal and the modulation signal.

6. The method according to claim 5, characterized in that, The frequency stabilization of the coupled laser is achieved by using a phase discrimination signal at a target position of the coupled laser, comprising: The phase-discrimination signal voltage at the target position of the coupled laser is fed back to the coupled laser generating device in real time to achieve frequency stabilization of the coupled laser.

7. The method according to claim 1, characterized in that The laser frequency of the detection laser frequency stabilization unit is stabilized at the transition frequency from the ground state to the intermediate state of the alkali metal atom; the laser frequency of the coupling laser frequency stabilization unit is stabilized at the transition frequency from the intermediate state to the preset Rydberg state of the alkali metal atom.

8. The method according to claim 2, wherein The detection beam splitting unit is further used to obtain the detection laser for experiment. The power ratio between the detection laser for experiment and the detection laser for frequency stabilization can be adjusted by the detection beam splitting unit.

9. The method according to claim 4, characterized in that, The coupling split beam unit is further used to obtain coupled laser light for experiment. The power ratio between the coupled laser light for experiment and the coupled laser light for frequency stabilization can be adjusted by the coupling split beam unit.

10. A laser frequency stabilization device applied to a Rydberg atom detection system, characterized in that, The device comprises: a detection laser frequency stabilization unit and a coupling laser frequency stabilization unit; The detection laser frequency stabilization unit includes a saturation absorption spectrum unit and a detection light phase discrimination feedback unit; The coupled laser frequency stabilization unit includes an EIT spectrum unit and a coupled optical phase discrimination feedback unit; The saturated absorption spectrum unit is used to output a modulated detection laser, which is input into the EIT spectrum unit after the frequency is stabilized; The EIT spectrum unit is used to generate an EIT spectrum signal; The detection light phase discrimination feedback unit is used to output a modulation signal; The coupled optical phase-discrimination feedback unit is used to perform frequency mixing based on the EIT spectrum signal and the modulation signal to obtain a phase-discrimination signal at a target position of the coupled laser, thereby achieving frequency stabilization of the coupled laser.

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