Integrated two-photon excited rydberg atom microwave detection system and working method thereof

Abstract

The application relates to the fields of quantum precision measurement and microwave detection technology, and discloses an integrated two-photon excited Rydberg atom microwave detection system and a working method thereof, which comprises a circuit control and signal processing module, a detection laser generation module, a coupling laser generation module, a frequency locking light path module and an integrated probe. The laser generation, frequency stabilization, atomic cell detection and signal processing functions are highly integrated in a case, without the need of complex optical path adjustment, so that the system is high in stability, small in size, light in weight and convenient to use, and is suitable for microwave electric field measurement in various field environments.

Description

Technical Field

[0001] This invention relates to the field of quantum precision measurement and microwave detection technology, and in particular to an integrated two-photon excited Rydberg atom microwave detection system and its working method. Background Technology

[0002] Rydberg atoms are highly excited-state atoms with very large principal quantum numbers n, which possess extremely large electric dipole moments (within the range of n). 4 (proportional to n) and polarizability (with n) 7 The response to microwave electric fields is directly proportional to the electromagnetic field strength. Microwave detection technology based on Rydberg atoms utilizes the electromagnetically induced transparency (EIT) effect to achieve self-calibration and high-sensitivity measurement of microwave electric field strength. The measurement results can be directly traced back to the atomic constant without the need for external calibration.

[0003] Traditional two-photon excited Rydberg atom microwave detection systems typically consist of multiple independent devices, including: at least two independent lasers (a probe laser and a coupling laser), a complex free-space optical path system, a laser frequency stabilization system, an atomic gas cell, a microwave signal source, a photodetector, an oscilloscope, a lock-in amplifier, and a computer control system. These devices are bulky and heavy, requiring complex optical path adjustments and system calibrations by professionals. The systems suffer from poor stability and are highly susceptible to environmental vibrations, temperature changes, and other factors, making them unsuitable for practical use.

[0004] While there have been some attempts to miniaturize the Rydberg atomic microwave detection system in existing technologies, such as coupling the atomic gas cell with optical fiber to make the probe portable, or integrating the laser and frequency stabilization system into a single chassis, these solutions still do not achieve complete integration of the entire system. The laser system, integrated gas cell, and signal processing system remain independent devices, which cannot fundamentally solve the problems of large system size, poor stability, and inconvenience of use.

[0005] Therefore, there is an urgent need to develop a highly integrated two-photon excited Rydberg atom microwave detection system that integrates all functional modules into a single chassis, achieving system miniaturization, high stability, and ease of use to meet the needs of on-site microwave measurements. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention provides an integrated two-photon excited Rydberg atom microwave detection system and its operating method. This system highly integrates laser generation, frequency stabilization, atomic gas cell detection, and signal processing functions into a single chassis, eliminating the need for complex optical path adjustments. The system is highly stable, small in size, lightweight, and easy to use, making it suitable for microwave electric field measurements in various field environments.

[0007] The technical solution adopted in this invention is as follows: An integrated two-photon excited Rydberg atom microwave detection system includes a circuit control and signal processing module, a detection laser generation module, a coupling laser generation module, a frequency-locked optical path module, and an integrated probe; The circuit control and signal processing module is electrically connected to the detection laser generation module, the coupling laser generation module, the frequency-locked optical path module, and the integrated probe, respectively. The detection laser generation module generates a detection laser, which is divided into two paths. One path enters the frequency-locking optical path module for frequency stabilization, and the other path enters the integrated probe for two-photon excitation of Rydberg atoms. The coupled laser generation module generates coupled laser, which is divided into two paths. One path enters the frequency-locking optical path module for frequency stabilization, and the other path enters the integrated probe for two-photon excitation of Rydberg atoms. The frequency-locking optical path module locks the frequencies of the probe laser and the coupling laser, respectively. The integrated probe is used to receive the microwave field to be measured, and to realize the interaction between the Rydberg atom and the microwave field by two photons. It outputs a probe light signal carrying microwave information to the circuit control and signal processing module for microwave parameter demodulation.

[0008] Furthermore, the circuit control and signal processing module, the detection laser generation module, the coupling laser generation module, and the frequency-locked optical path module are all integrated into a single chassis. This chassis is optically connected to the integrated probe via optical fiber and electrically connected via radio frequency cable.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses a frequency-locked optical path module to independently lock the frequencies of the probe laser and the coupling laser, effectively suppressing laser frequency drift and ensuring the long-term stability of the two-photon excitation process, thereby significantly improving the frequency resolution and sensitivity of microwave detection.

[0010] This invention employs a two-photon excitation scheme for Rydberg atoms, which, compared to single-photon excitation, can effectively reduce stray light background and atomic recoil effect, improve the signal-to-noise ratio of the probe light signal, and thus enhance the dynamic range and accuracy of microwave field strength measurement.

[0011] This invention integrates the circuit control and signal processing module, the detection laser generation module, the coupling laser generation module, and the frequency-locked optical path module into a single chassis. The chassis is optically connected to the integrated probe via optical fiber and electrically connected via radio frequency cable. This eliminates the need for complex optical path adjustments, resulting in a highly stable system that is small in size, lightweight, and easy to use, making it suitable for microwave electric field measurements in various field environments. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is an overall architecture block diagram of an integrated two-photon excited Rydberg atom microwave detection system provided in one embodiment. Detailed Implementation

[0014] The technical solution of the present invention will now be clearly and completely described through specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0015] Figure 1 This is an overall structural block diagram of an integrated two-photon excited Rydberg atom microwave detection system provided in one embodiment. The integrated two-photon excited Rydberg atom microwave detection system includes a circuit control and signal processing module 11, a detection laser generation module 12, a coupling laser generation module 13, a frequency-locked optical path module 14, and an integrated probe 15. The circuit control and signal processing module 11 is electrically connected to the detection laser generation module 12, the coupling laser generation module 13, the frequency-locked optical path module 14, and the integrated probe 15 via electrical signal links shown by dashed lines. The detection laser generation module 12 and the coupling laser generation module 13 are optically connected to the frequency-locked optical path module 14 and the integrated probe 15 via optical path links shown by solid lines. The frequency-locked optical path module 14 and the integrated probe 15 are electrically and optically connected to the circuit control and signal processing module 11 via electrical signal links and optical links, respectively.

[0016] The circuit control and signal processing module 11 is electrically connected to the detection laser generation module 12, the coupling laser generation module 13, the frequency-locked optical path module 14, and the integrated probe 15, respectively.

[0017] The detection laser generation module 12 generates a detection laser, which is divided into two paths. One path enters the frequency-locked optical path module 14 for frequency stabilization, and the other path enters the integrated probe 15 for two-photon excitation of Rydberg atoms. The coupled laser generation module 13 generates a coupled laser, which is divided into two paths. One path enters the frequency-locked optical path module 14 for frequency stabilization, and the other path enters the integrated probe 15 for two-photon excitation of Rydberg atoms. The frequency-locked optical path module 14 locks the frequencies of the probe laser and the coupling laser, respectively. The integrated probe 15 is used to receive the microwave field to be measured, and to realize the interaction between the Rydberg atom and the microwave field by two photons. It outputs a probe light signal carrying microwave information to the circuit control and signal processing module 11 for microwave parameter demodulation.

[0018] Specifically, the circuit control and signal processing module 11 outputs a probe laser control signal 111 to the probe laser generation module 12 for controlling and frequency locking of the probe laser. The circuit control and signal processing module 11 also outputs a coupling laser control signal 112 to the coupling laser generation module 13 for controlling and frequency locking of the coupling laser.

[0019] The probe laser generation module 12 outputs the probe laser frequency stabilization branch 121 to the frequency-locked optical path module 14 to generate a frequency-locked reference signal, and outputs the probe laser detection branch 122 to the integrated probe 15 to excite atoms in the first stage.

[0020] The coupled laser generation module 13 outputs the coupled laser frequency stabilization branch 131 to the frequency locking optical path module 14 to generate a frequency locking reference signal, and outputs the coupled laser detection branch 132 to the integrated probe 15 to excite atoms in the second stage. The frequency-locked optical path module 14 outputs a photoelectric detection signal 141 to the circuit control and signal processing module 11 to generate an error signal. Simultaneously, the circuit control and signal processing module 11 outputs a modulation and feedback signal 114 to the frequency-locked optical path module 14 to control the frequency-locked optical path. The frequency-locked optical path module 14 can lock the frequency based on a reference spectrum or using a reference resonant cavity, respectively, to lock the frequencies of the detection laser and the coupling laser.

[0021] The integrated probe 15 outputs a detection light signal 151 carrying microwave information to the circuit control and signal processing module 11 for signal processing to achieve microwave parameter demodulation. In addition, the circuit control and signal processing module 11 can also output a microwave local oscillator signal 113 to the integrated probe 15 depending on the strength of the detected microwave field signal.

[0022] The working principle of this invention is based on the electromagnetically induced transparency (EIT) effect of two-photon excited Rydberg atoms. Specifically, the working method of the integrated two-photon excited Rydberg atom microwave detection system includes the following steps: After the system is powered on, the circuit control and signal processing module 11 first controls the temperature control module to start working, stabilizing the temperature of the atomic gas chamber and the probe laser generation module 12 and the coupling laser generation module 13 at the corresponding set values. The circuit control and signal processing module 11 outputs a control signal to start the probe laser and the coupling laser in the probe laser generation module 11 and the coupling laser generation module 12, respectively, to generate the required probe laser and coupling laser; The frequency-locking optical path module 14 locks the frequency of the probe laser and the coupling laser respectively, locking the frequency of the probe laser to the transition line from the ground state to the intermediate state of the atom, and locking the frequency of the coupling laser to the transition line from the intermediate state to the desired Rydberg state. After frequency locking, the probe laser and the coupling laser are transmitted to the integrated probe 15, propagate in opposite directions in the atomic gas cell and coincide precisely; under two-photon resonance conditions, the atoms are excited to the corresponding Rydberg states, forming the EIT effect; When the microwave field to be measured enters the atomic gas cell through the microwave window, the microwave field interacts with the Rydberg atoms, causing the Rydberg energy level to split at AT or shift at Stark, and the EIT spectral line to split or shift accordingly. The photodetector detects the detection light signal passing through the atomic gas cell and converts it into an electrical signal, which is then input to the circuit control and signal processing module 11. The circuit control and signal processing module 11 acquires and processes the electrical signal, retrieves the microwave information of the external microwave field to be measured, and outputs the measurement results.

[0023] Furthermore, the circuit control and signal processing module 11 outputs the measurement results to an external computer for display and storage via a data interface.

[0024] To eliminate common-mode noise caused by relative frequency jitter between the probe laser and the coupling laser, and to suppress random fluctuations in two-photon detuning caused by environmental vibration and temperature drift, thereby improving the long-term stability and signal-to-noise ratio of microwave electric field measurement, a two-photon detuning cooperative locking unit is further added between the frequency-locked optical path module 14 and the circuit control and signal processing module 11. The two-photon detuning cooperative locking unit acquires the Rydberg atomic electromagnetic induction transparency (EIT) signal output by the integrated probe 15 in real time. Through the digital proportional-integral-derivative (PID) controller in the circuit control and signal processing module 11, it synchronously calculates the deviation between the actual frequency difference between the probe laser and the coupling laser and the theoretical Rydberg resonant frequency, and generates two feedback correction signals based on the deviation value. One signal is fed back to the probe laser generation module 12, and the other is fed back to the coupling laser generation module 13, so that the output frequencies of the probe laser generation module 12 and the coupling laser generation module 13 remain relatively locked. This scheme can suppress the long-term drift of the two-photon resonance frequency from the megahertz level to the sub-kilohertz level, effectively suppress the common-mode relative noise between the probe laser and the coupling laser, and keep the minimum detectable sensitivity of the microwave electric field stable for several hours of continuous operation. This is at least an order of magnitude better than the traditional independent frequency locking method.

[0025] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0026] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

[0027] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An integrated two-photon excited Rydberg atom microwave detection system, characterized in that, It includes a circuit control and signal processing module, a detection laser generation module, a coupling laser generation module, a frequency-locked optical path module, and an integrated probe; The circuit control and signal processing module is electrically connected to the detection laser generation module, the coupling laser generation module, the frequency-locked optical path module, and the integrated probe, respectively. The detection laser generation module generates a detection laser, which is divided into two paths. One path enters the frequency-locking optical path module for frequency stabilization, and the other path enters the integrated probe for two-photon excitation of Rydberg atoms. The coupled laser generation module generates coupled laser, which is divided into two paths. One path enters the frequency-locking optical path module for frequency stabilization, and the other path enters the integrated probe for two-photon excitation of Rydberg atoms. The frequency-locking optical path module locks the frequencies of the probe laser and the coupling laser, respectively. The integrated probe is used to receive the microwave field to be measured, and to realize the interaction between the Rydberg atom and the microwave field by two photons. It outputs a probe light signal carrying microwave information to the circuit control and signal processing module for microwave parameter demodulation.

2. The integrated two-photon excited Rydberg atom microwave detection system according to claim 1, characterized in that, The circuit control and signal processing module outputs a probe laser control signal to the probe laser generation module for probe laser control and frequency locking. The circuit control and signal processing module outputs a coupling laser control signal to the coupling laser generation module for coupling laser control and frequency locking.

3. The integrated two-photon excited Rydberg atom microwave detection system according to claim 1, characterized in that, The frequency-locking optical path module is frequency-locked based on a reference spectrum or using a reference resonant cavity.

4. The integrated two-photon excited Rydberg atom microwave detection system according to claim 1, characterized in that, The frequency-locked optical path module outputs a photoelectric detection signal to the circuit control and signal processing module to generate an error signal; at the same time, the circuit control and signal processing module outputs a modulation and feedback signal to the frequency-locked optical path module to control the frequency-locked optical path.

5. The integrated two-photon excited Rydberg atom microwave detection system according to claim 1, characterized in that, The circuit control and signal processing module also selectively outputs microwave local oscillator signals to the integrated probe based on the strength of the detected microwave field signal.

6. The integrated two-photon excited Rydberg atom microwave detection system according to any one of claims 1 to 5, characterized in that, The circuit control and signal processing module, the detection laser generation module, the coupling laser generation module, and the frequency-locked optical path module are all integrated in a single chassis. The chassis is optically connected to the integrated probe via optical fiber and electrically connected via radio frequency cable.

7. The operating method of the integrated two-photon excited Rydberg atom microwave detection system as described in claim 1, characterized in that, Includes the following steps: After the system is powered on, the circuit control and signal processing module first controls the temperature control module to start working, stabilizing the temperature of the atomic gas chamber and the probe laser generation module, the probe laser and the coupling laser in the coupling laser generation module at the corresponding set values. The circuit control and signal processing module outputs control signals to start the probe laser and the coupling laser in the probe laser generation module and the coupling laser generation module, respectively generating the required probe laser and coupling laser; The frequency-locking optical path module locks the frequency of the probe laser and the coupling laser respectively, locking the frequency of the probe laser to the transition line from the ground state to the intermediate state of the atom, and locking the frequency of the coupling laser to the transition line from the intermediate state to the desired Rydberg state. After frequency locking, the probe laser and the coupling laser are transmitted to the integrated probe, propagate in opposite directions in the atomic gas cell and precisely coincide; under two-photon resonance conditions, the atoms are excited to the corresponding Rydberg states, forming the EIT effect; When the microwave field to be measured enters the atomic gas cell through the microwave window, the microwave field interacts with the Rydberg atoms, causing the Rydberg energy level to split at the AT level or shift at the Stark level. The EIT spectral line also splits or shifts accordingly. The photodetector detects the detection light signal passing through the atomic gas cell and converts it into an electrical signal, which is then input to the circuit control and signal processing module. The circuit control and signal processing module acquires and processes the electrical signal, retrieves the microwave information of the external microwave field to be measured, and outputs the measurement results.

8. The operating method of the integrated two-photon excited Rydberg atom microwave detection system as described in claim 7, characterized in that, The circuit control and signal processing module outputs the measurement results to an external computer for display and storage via a data interface.

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