Laser multi-parameter collaborative feedback stabilization system for quantum sensing

Abstract

The invention relates to the technical field of laser control, and particularly discloses a quantum sensing laser multi-parameter cooperative feedback stabilization system, which comprises a medium intrinsic probe module, a multi-parameter error decoupling and fusion module, a cooperative feedback control module and a laser execution module. The stable system is effective laser parameters which are crucial to quantum state control and reading, but not isolated parameters of a laser, so that long-term accurate matching of laser and a medium energy level structure is ensured, and the fidelity and long-time stability of quantum storage are improved. An intrinsic error signal is directly obtained from the interior of a medium, a cooperative error vector is generated through decoupling fusion, and an execution module is driven to perform cooperative feedback control on laser frequency, phase and power, so that accurate matching of laser parameters and medium dynamic requirements is realized, and quantum storage fidelity and long-term stability of a system are improved.

Description

Technical Field

[0001] This invention belongs to the field of laser control technology, specifically relating to a multi-parameter collaborative feedback stabilization system for lasers used in quantum sensing. Background Technology

[0002] Quantum precision measurement and sensing technology is a core driving force for advancing cutting-edge physics exploration and the development of next-generation high-precision metrology standards. It achieves sensitivity beyond the classical limit by manipulating and measuring quantum states. Sensing schemes based on quantum systems such as atoms, ions, or solid-state defects have performance limits that are highly dependent on the stability of the laser source used for pumping and detection.

[0003] Quantum storage, as a key interface technology connecting quantum communication and quantum computing, relies on the high-fidelity storage and retrieval of photon states using media such as atomic ensembles or rare-earth-doped crystals. This process requires long-term and precise matching between multiple parameters of the pump laser, such as frequency, phase, and power, and the energy level structure of the storage medium.

[0004] Independent laser frequency and phase stabilization systems are employed, such as frequency locking via saturable absorption spectroscopy or Fabry-Perot cavities, or phase noise suppression via electronic feedback loops. However, these methods have significant limitations: they primarily stabilize the laser's own parameters, neglecting the dynamic frequency shifts and phase changes in the storage medium caused by environmental temperature fluctuations, external magnetic field disturbances, or internal relaxation processes. This mismatch between laser parameters and the actual requirements of the medium introduces uncontrollable decoherence during long-term storage or high-fidelity operation, directly leading to degradation of storage fidelity and sensing signal-to-noise ratio. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-parameter collaborative feedback stabilization system for lasers used in quantum sensing, so as to solve the technical contradiction in the prior art where the mismatch between the laser parameter stabilization system and the dynamic characteristics of the quantum storage medium leads to the degradation of quantum storage fidelity and sensing signal-to-noise ratio.

[0006] To achieve the above objectives, this invention proposes a multi-parameter cooperative feedback stabilization system for lasers used in quantum sensing. This system includes a medium intrinsic probe module, a multi-parameter error decoupling and fusion module, a cooperative feedback control module, and a laser execution module. The medium intrinsic probe module is used to acquire, in real time, the intrinsic physical quantities related to the laser interaction within the quantum storage medium; the multi-parameter error decoupling and fusion module receives signals from the medium intrinsic probe module and calculates the cooperative error vector of the laser frequency, phase, and power relative to the current optimal operating point of the medium; the cooperative feedback control module generates multi-dimensional composite control commands based on the cooperative error vector; and the laser execution module responds to the composite control commands and cooperatively adjusts the laser's frequency, phase, and power output.

[0007] The intrinsic probe module of the medium specifically includes a quantum state preparation unit, a weak measurement unit, and an intrinsic signal extraction unit. The quantum state preparation unit uses the laser to be stabilized to prepare a specific reference quantum state in the quantum storage medium that is sensitive to changes in laser parameters. This reference quantum state is either a coherently populated trapped state or a Raman memory state. The weak measurement unit performs non-destructive measurements on the prepared reference quantum state, either by detecting the fluorescence intensity emitted by the auxiliary energy level coupled to the reference quantum state or by detecting the polarization rotation angle of the probe light passing through the medium. The intrinsic signal extraction unit receives the output signal from the weak measurement unit and, through lock-in amplification and digital signal processing, extracts three independent intrinsic error signals characterizing the laser frequency detuning, phase accumulation error, and effective light intensity actually experienced within the medium.

[0008] The multi-parameter error decoupling and fusion module specifically includes an error decoupling algorithm unit and an error fusion decision unit. The error decoupling algorithm unit incorporates a pre-calibrated medium response Jacobian matrix. This matrix describes the linear mapping between the three intrinsic error signals output by the intrinsic probe module and the input disturbances at the three independent control ports of the laser: frequency, phase, and power. The error decoupling algorithm unit decouples the three intrinsic error signals into three independent error components corresponding to the laser's frequency control, phase control, and power control ports by solving for the inverse of this Jacobian matrix. The error fusion decision unit receives the three decoupled independent error components and generates a 3D cooperative error vector according to a preset error fusion strategy. The error fusion strategy is as follows: when the absolute value of any error component is less than its corresponding first threshold, the component retains its original value in the cooperative error vector; when the absolute value of any error component is greater than or equal to its corresponding first threshold but less than the second threshold, the value of the component in the cooperative error vector is multiplied by a decay coefficient between 0 and 1; when the absolute value of any error component is greater than or equal to its corresponding second threshold, the error fusion decision unit triggers a global relocking protocol, and the cooperative error vector is reset to the initial setting value given by the medium calibration data.

[0009] The cooperative feedback control module specifically includes a multi-input multi-output (MIMO) controller and an instruction synthesis unit. The MIMO controller receives a 3D cooperative error vector from the error fusion decision unit. This controller employs a state-space feedback control algorithm, and its state variables include the current value of the cooperative error vector, its integral, and its derivative. The controller's transfer function matrix is ​​designed to actively suppress coupling between the three control loops of the laser frequency, phase, and power, while ensuring a stability margin for the system within a preset bandwidth. The instruction synthesis unit vector-superimposes the three preliminary control voltages output from the MIMO controller with programmed scanning or modulation instructions from outside the system to generate the final three composite control instructions.

[0010] The laser execution module specifically includes a frequency execution unit, a phase execution unit, and a power execution unit. The frequency execution unit receives the frequency control component from the composite control command. This unit, composed of a piezoelectric ceramic-driven external cavity grating or an electro-optic modulator, is used to adjust the output light frequency of the laser. The phase execution unit receives the phase control component from the composite control command. This unit, composed of a high-speed electro-optic phase modulator or an acousto-optic modulator, is used to adjust the phase of the laser beam. The power execution unit receives the power control component from the composite control command. This unit, composed of an acousto-optic modulator or an electroabsorption modulator, is used to adjust the output power of the laser beam. The response bandwidth of each of the three execution units is more than twice the closed-loop bandwidth of the cooperative feedback control module.

[0011] In one embodiment of the present invention, the weak measurement unit in the intrinsic probe module of the medium employs a dual-color light detection scheme. Specifically, while preparing a reference quantum state using pump light, a weak probe light with a fixed frequency mistuning from the pump light is introduced. The polarization direction of this probe light is orthogonal to the pump light. When the laser parameters match the energy level of the medium, the medium is transparent to the probe light; when mismatch exists, the electromagnetically induced transparency window of the medium shifts, causing the polarization plane of the probe light to rotate. The intrinsic signal extraction unit analyzes the magnitude and direction of the polarization state rotation angle of the probe light and simultaneously demodulates the frequency and phase error information.

[0012] Furthermore, the global relocking protocol executed by the error fusion decision unit in the multi-parameter error decoupling and fusion module includes a media relaxation waiting period lasting from 10 milliseconds to 100 milliseconds. During this waiting period, the cooperative feedback control module suspends outputting control commands, while the laser execution module maintains its previous state. After the waiting period ends, the system reinitializes the cooperative error vector based on the media calibration data and uses a proportional-integral control algorithm for rapid coarse locking. Once all error components are below their corresponding first thresholds, the system automatically switches back to the normal operation mode of the multi-input multi-output controller.

[0013] Furthermore, the state observer of the state-space feedback control algorithm in the multi-input multi-output controller of the collaborative feedback control module is implemented using a Kalman filter. This Kalman filter uses the output signal of the intrinsic probe module of the medium and the driving current of the laser actuation module as observation inputs to estimate the state variables that cannot be directly measured inside the system, including the dynamic perturbations of the laser parameter requirements caused by the instantaneous temperature fluctuations and local magnetic field fluctuations of the quantum storage medium.

[0014] Furthermore, the system also includes a system health monitoring and adaptive module. This module monitors in real time the signal-to-noise ratio of the intrinsic probe module, the error vector norm calculated by the multi-parameter error decoupling and fusion module, and the output saturation of the collaborative feedback control module. When the signal-to-noise ratio is detected to be lower than a preset threshold, the error vector norm continuously exceeds the warning value, or the time percentage of any control channel output reaching saturation exceeds 5%, the module determines that the system health has declined and automatically adjusts the attenuation coefficient in the error fusion decision unit or the integral time constant of the multi-input multi-output controller to optimize the system's stability under non-ideal operating conditions.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention directly senses changes in intrinsic physical quantities within the quantum storage medium through an intrinsic probe module, shifting the reference standard for feedback control from the external optical cavity to the subject of the quantum sensing process itself. This resolves the core contradiction of mismatch between laser parameters and the dynamic requirements of the medium. The system stabilizes the effective laser parameters crucial for quantum state manipulation and reading, rather than the isolated parameters of the laser itself. This ensures long-term precise matching between the laser and the medium's energy level structure, improving the fidelity and long-term stability of quantum storage.

[0016] 2. This invention achieves joint calculation and coordinated control of multiple parameter errors (frequency, phase, and power) through the collaborative design of a multi-parameter error decoupling and fusion module and a collaborative feedback control module. This system not only eliminates crosstalk between traditional independent control loops but also intelligently handles disturbances of different magnitudes through an error fusion strategy, and initiates an orderly global relocking protocol in the event of a large lock-out. This approach endows the system with high precision, strong robustness, and rapid recovery capability, effectively coping with complex dynamic frequency shifts and phase changes caused by environmental temperature fluctuations and magnetic field disturbances.

[0017] 3. The system health monitoring and adaptive module introduced in this invention endows the system with the ability to self-diagnose and optimize parameters. By monitoring key performance indicators and adaptively adjusting control parameters, the system can maintain optimal closed-loop stability even under conditions of slow drift in medium properties or continuous deterioration of the external environment. This greatly enhances the long-term reliability and maintenance-free operation of the system in real experimental environments or practical quantum sensing devices, providing crucial hardware support for the transition of quantum precision measurement technology from the laboratory to practical applications. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall technical architecture of the multi-parameter collaborative feedback stabilization system for quantum sensing lasers proposed in this invention; Figure 2 This is a schematic diagram of the core principle framework of the multi-parameter error decoupling and fusion module in this invention; Figure 3 This is a logical flow diagram of the collaborative feedback control module in this invention; Figure 4 This is a schematic diagram of the multi-level interaction relationship and data flow between the laser execution module and the quantum storage medium in this invention. Detailed Implementation

[0019] The overall technical architecture of the multi-parameter cooperative feedback stabilization system for quantum sensing lasers proposed in this invention is shown in the attached figure. Figure 1 As shown in the figure, the system consists of four core functional units: a medium intrinsic probe module, a multi-parameter error decoupling and fusion module, a collaborative feedback control module, and a laser execution module. These units are interconnected via a high-speed digital signal link and an analog control channel, forming an adaptive and stable system based on the dynamic response within the quantum storage medium as the feedback benchmark. Please refer to the appendix. Figure 1 To be continued Figure 4 Throughout the entire system operation, all data processing, instruction generation, and execution actions revolve around the fundamental goal of improving the fidelity of laser-medium interaction in the quantum sensing process.

[0020] First, the specific implementation structure and workflow of the intrinsic probe module of the medium are detailed. This module is the sensing front end of the entire feedback system, and its function is to convert the intrinsic response of the quantum storage medium to changes in laser parameters into a measurable and processable electrical signal. The intrinsic probe module of the medium consists of three sub-units: a quantum state preparation unit, a weak measurement unit, and an intrinsic signal extraction unit. The quantum state preparation unit uses the main laser beam to be stabilized to excite and prepare a specific reference quantum state in a quantum storage medium such as a cold atom ensemble or a solid-state doped crystal placed in a temperature-controlled magnetically shielded cavity. This reference quantum state is preferably a coherent population trapped state or a Raman memory state, because it is highly sensitive to laser frequency detuning, phase drift, and light intensity fluctuations, and has good non-destructive readout characteristics under weak detection conditions. In specific operation, one path of the main laser is led out as pump light through an optical fiber beam splitter and injected into the quantum storage medium. When the laser frequency precisely matches the two-photon resonance condition between the two ground state energy levels of the medium, the system enters the dark state, and the atomic population is trapped in the non-radiative transition channel, thereby forming a stable reference quantum state.

[0021] A weak measurement unit follows, used for non-destructive detection of the aforementioned reference quantum state. In this embodiment, the weak measurement unit employs a dual-color light detection scheme, introducing an orthogonally polarized weak probe light simultaneously with the pump light. The frequency of this probe light has a fixed, preset detuning relative to the pump light, typically set at the edge region of the electromagnetically induced transparent window. When the laser parameters perfectly match the energy level structure of the medium, the medium exhibits high transparency to the probe light, and its polarization state remains unchanged. Once the laser frequency or phase shifts, the electromagnetically induced transparent window moves accordingly, causing the probe light to undergo partial absorption or dispersion effects, thereby causing a measurable rotation of its polarization plane. The magnitude and direction of this polarization rotation angle encode information about the frequency detuning and phase accumulation error, respectively. After passing through the medium, the probe light enters a polarization analysis system, which consists of a quarter-wave plate, a polarization beam splitter, and two balanced photodetectors, capable of converting minute changes in the polarization state into differential current signals. This differential signal is the original output of the weak measurement unit. Its signal-to-noise ratio is better than 60 dB, and its bandwidth covers 0 to 10 kHz, which is sufficient to capture slow and fast changes caused by environmental disturbances.

[0022] The intrinsic signal extraction unit receives the differential current signal from the weak measurement unit and performs high-precision signal conditioning and feature extraction. This unit first converts the current signal into a voltage signal through a transimpedance amplifier, and then sends it to a lock-in amplifier for coherent demodulation. The reference signal for the lock-in amplifier is synchronously provided by the modulation source of the main laser, ensuring that the demodulation process is in phase and frequency with the laser parameter disturbances. The demodulated baseband signal is then sampled by a 24-bit high-resolution analog-to-digital converter at a sampling rate set to 100 kHz to meet the Nyquist sampling theorem requirement for a 10 kHz signal bandwidth. The digital signal processor performs real-time filtering, detrending, and normalization on the sampled data, ultimately separating three independent intrinsic error signals: the first signal characterizes the actual detuning of the laser frequency relative to the two-photon resonance point of the medium, in megahertz; the second signal reflects the phase error accumulated along the laser propagation path in the medium, in radians; and the third signal represents the effective light intensity actually felt by the medium, after deducting the effects of background scattering and probe crosstalk, in milliwatts per square centimeter. These three intrinsic error signals constitute the original input for subsequent error decoupling and fusion processing, with an update cycle of 10 microseconds, ensuring that the system has sufficient dynamic response capability.

[0023] Please refer to the attached document. Figure 2 The multi-parameter error decoupling and fusion module receives the three intrinsic error signals mentioned above and performs decoupling and fusion operations. This module consists of two parts: an error decoupling algorithm unit and an error fusion decision unit. The core of the error decoupling algorithm unit is a 3×3 medium response Jacobian matrix pre-calibrated experimentally. The elements of this matrix Indicates the first One laser control port ( =1 corresponds to the frequency. =2 corresponds to the phase, When a unit step disturbance is applied to the power corresponding to =3, at the first... The steady-state response amplitudes generated on each intrinsic error signal channel. The calibration process is completed during the system initialization phase: small signal perturbations of known amplitudes are sequentially applied to the frequency, phase, and power execution units, while the output response of the intrinsic signal extraction unit is recorded. The matrix is ​​then obtained through least-squares fitting. All nine elements. During normal operation, the error decoupling algorithm unit calculates in real time. inverse matrix And the eigenvector at the current time. The decoupled independent error component vectors are obtained. ,in This is the correction amount that needs to be applied to the frequency control terminal. This is the correction amount for the phase control terminal. This is the calibration value for the power control terminal. This is a transpose. , , These correspond to the original, undecoupled frequency error, phase error, and power error components, respectively. This decoupling process effectively eliminates cross-channel interference caused by laser physical structure coupling (such as intensity fluctuations caused by piezoelectric ceramics driving external cavity gratings) or nonlinear response of the medium.

[0024] Error fusion decision unit receives The vector is used to generate the final collaborative error vector based on a preset nonlinear fusion strategy. This strategy is based on a triple threshold judgment mechanism: for each error component... ( =1,2,3), set the first threshold. With the second threshold ,in The typical value is the first threshold of the frequency error. =0.1 MHz, the second threshold for frequency error =1 MHz; the first threshold for phase error =0.01 radians, the second threshold for phase error =0.1 radians; the first threshold for power error =0.5 milliwatts per square centimeter, the second threshold for power error =5 milliwatts per square centimeter. When hour, ( for The i-th component) of the system is in the high-precision fine-tuning region; when hour, The attenuation coefficient A typical value of 0.7 is used to suppress overshoot response under moderate disturbances; when When a large-scale loss of lock is detected, the error fusion decision unit immediately triggers the global relock protocol. After this protocol is initiated, the cooperative feedback control module suspends all control command output for 50 milliseconds (between 10 and 100 milliseconds). During this period, the laser execution module maintains its previous valid state to allow the quantum storage medium to complete the relaxation process and eliminate the non-equilibrium population distribution caused by strong disturbances. After 50 milliseconds, the system reads the pre-stored medium calibration data from the non-volatile memory and... Reset to initial settings ( This is the initial value for the frequency error; This is the initial value for the phase error; (Assuming an initial power error value) and switching to proportional-integral control mode for coarse locking. The proportional gain of the coarse locking controller is set to 5 times that of normal mode, and the integral time constant is shortened to 1 millisecond to achieve fast convergence. When all Lower than their respective Afterwards, the system seamlessly switches back to the normal operation mode of the MIMO controller.

[0025] The collaborative feedback control module is attached. Figure 3 As shown, it is responsible for converting the cooperative error vector. This is translated into specific execution instructions. This module includes a multiple-input multiple-output (MIMO) controller and an instruction synthesis unit. The MIMO controller is implemented using a discrete-time state-space model, and its state equation is: ; ; in It is the state vector at the "next sampling time" in discrete time. The dimension is 9 (3 error components and their integrals and derivatives); input The initial control voltage vector output by the controller; output This represents the initial control voltage vector for the final output. System matrix. , , , Through quantitative indicators The design of robust control synthesis methods aims to minimize the impact of loop slack while ensuring that the closed-loop poles are located within the unit circle (ensuring stability). arrive The transfer function matrix The norm is used to suppress inter-loop coupling and improve anti-interference capability. The controller's sampling period is synchronized with the intrinsic signal extraction unit, which is 10 microseconds, and the closed-loop bandwidth is designed to be 5 kHz.

[0026] To improve the accuracy of state estimation, the controller's built-in state observer employs a Kalman filter. The filter's observation input consists of two parts: first, three intrinsic error signals output from the intrinsic probe module of the medium; and second, the drive current feedback signals from each execution unit in the laser execution module. By fusing these two types of information, the Kalman filter can estimate latent state variables that cannot be directly measured online, such as the equivalent perturbation of the energy level Stark frequency shift caused by ambient temperature fluctuations in the quantum storage medium, or the Zeeman splitting shift caused by local residual magnetic field fluctuations. These estimates are fed back into the state vector for feedforward compensation, thereby significantly improving the system's ability to suppress slowly varying environmental disturbances.

[0027] The instruction synthesis unit receives three preliminary control voltages from the multiple-input multiple-output controller. ( The initial control voltage for the frequency channel output by the multi-input multi-output controller. The initial control voltage for the phase channel output by the multiple-input multiple-output controller. This involves vector-superimposing the initial control voltage of the power channel output by the MIMO controller with programmed instructions from an external host computer. These external instructions may include frequency sweep ramps, phase-modulated sine waves, or power step sequences to perform specific operations in quantum sensing tasks (such as Raman transition pulses, Ramsey interference, etc.). The synthesis rule is as follows: Each component is independently superimposed. The output from the 16-bit digital-to-analog converter drives the laser actuation module. The step control voltage is in vector form. The voltage vector is an external command. This is the synthesized composite control voltage vector. yes The three channel control commands, which are split off, correspond to the frequency, phase, and power dimensions, respectively, and are the final control signals output to the hardware.

[0028] Laser actuation module as attached Figure 4 As shown, the control directly acts on the laser body to achieve real-time control of the output light field. This module consists of a frequency execution unit, a phase execution unit, and a power execution unit, which are physically independent but coordinated in control. The frequency execution unit adopts a piezoelectric ceramic-driven external cavity grating structure. The piezoelectric ceramic has a telescoping stroke of 10 micrometers, corresponding to a frequency tuning range of ±500 MHz and a response bandwidth of 20 kHz, far exceeding the 5 kHz closed-loop bandwidth of the coordinated feedback control module.

[0029] The phase actuator employs a lithium niobate electro-optic phase modulator with a half-wave voltage of 4 volts, a phase modulation depth of up to 2π radians, and a 3 dB bandwidth of 50 MHz, ensuring hysteresis-free phase control. The power actuator uses an acousto-optic modulator with a diffraction efficiency greater than 85%, insertion loss less than 1 dB, and a modulation bandwidth of 1 MHz, enabling continuous power regulation from 0 to 100 milliwatts. The drive circuits of all three actuators are equipped with overvoltage and overcurrent protection and feature local feedback loops to compensate for device nonlinearities. The response delay of all actuators is controlled within 1 microsecond, ensuring a phase margin of greater than 45 degrees for the entire closed-loop system.

[0030] In addition, this system also integrates a system health monitoring and adaptive module, although this module is not included in the appendix. Figure 1 Although highlighted separately, its function permeates the entire control process. This module continuously collects three key indicators: first, the signal-to-noise ratio of the output signal from the intrinsic probe module, obtained by calculating the ratio of signal power to floor noise power; second, the cooperative error vector norm output by the multi-parameter error decoupling and fusion module. Thirdly, the percentage of time during which the output voltage of any control channel in the collaborative feedback control module reaches its hardware saturation limit (e.g., ±10 volts). The system's preset health thresholds are as follows: signal-to-noise ratio below 40 dB. For a continuous 5-second duration, the composite unit exceeds 3 MHz·radians·mW / cm², and the saturation time percentage of any channel exceeds 5%. Once any indicator exceeds the limit, the system determines that its health has declined and automatically triggers an adaptive adjustment mechanism: if the control jitter is caused by a decrease in signal-to-noise ratio, the attenuation coefficient in the error fusion decision unit is increased. To reduce control sensitivity, the value is reduced to 0.9. If the steady-state error increases due to medium drift, the integral time constant of the MIMO controller is increased from 10 milliseconds to 50 milliseconds to enhance low-frequency disturbance suppression. All adjustments are made smoothly to avoid introducing new transient disturbances.

[0031] The entire system executes a complete initialization sequence upon startup: first, optical pumping and magneto-optical trap cooling are performed on the quantum storage medium (if it is an atomic ensemble), or optical pump polarization is performed (if it is a solid-state medium); then, the online calibration of the medium response Jacobian matrix J is performed; next, the pre-stored initial settings are loaded; finally, closed-loop control is initiated. During steady-state operation, the system completes a full sensing-calculation-control cycle every 10 microseconds, ensuring that the laser parameters always track the optimal operating point of the medium.

[0032] Example 2: In another embodiment, the weak measurement unit of the intrinsic probe module uses fluorescence detection instead of polarization rotation detection. Specifically, after the quantum state preparation unit prepares a coherent population trapped state in a cold rubidium 87 atom ensemble, the weak measurement unit collects the quantum states coupled with the reference quantum state through a high numerical aperture objective lens. (Energy level symbol for rubidium-87 atom) 780 nm fluorescence from spontaneous emission of the auxiliary energy level. The fluorescence intensity exhibits a Lorentzian linear relationship with the laser-medium detuning, with its peak position corresponding to the two-photon resonance point. The intrinsic signal extraction unit uses a single-photon counting module to count the fluorescence photons. After Poisson statistical correction, the frequency detuning is demodulated in real time by fitting a Lorentz curve. The phase error is indirectly obtained by introducing a known phase modulation into the pump light and measuring the sideband response amplitude of the fluorescence intensity. This scheme is suitable for isotropic media where polarization detection is not feasible, such as certain erbium-doped crystals.

[0033] Meanwhile, the error fusion strategy in the multi-parameter error decoupling and fusion module can be replaced with a fuzzy logic-based decision-making mechanism. This mechanism divides the three error components into five linguistic variables: negative large, negative small, zero, positive small, and positive large, establishing a 3D fuzzy rule base. For example, if the frequency error is positive large and the phase error is zero, the frequency component in the cooperative error vector takes an attenuated value, while the phase component retains its original value. The fuzzy inference result is generated after defuzzification using the centroid method. This strategy is more robust in scenarios with strong nonlinearity or where the Jacobian matrix is ​​difficult to calibrate accurately.

[0034] The multi-input multi-output controller of the collaborative feedback control module can also use a neural network adaptive controller instead of the state-space model. This neural network has a three-layer feedforward structure, with the input layer receiving... The network uses historical values ​​and hidden layers containing 20 sigmoid-activated neurons, with the output layer generating the control voltage. Network weights are updated via online backpropagation to minimize the sum of squared control errors. This approach is suitable for long-term operation scenarios where the dynamic characteristics of the medium change significantly over time.

[0035] In the laser actuation module, the power actuation unit can be replaced with an electro-absorption modulator, which is particularly suitable for semiconductor laser integration solutions. This modulator is directly integrated into the laser chip pigtail, with a modulation bandwidth of up to 10 GHz, but temperature control is required to compensate for absorption spectrum drift. The frequency actuation unit can also adopt a direct current tuning method, implemented through a high-speed laser diode drive circuit, with a tuning efficiency of 100 MHz per milliampere. However, it should be noted that current tuning introduces additional phase noise, so it must be modeled and compensated for in the error decoupling algorithm.

[0036] In this embodiment, the system health monitoring and adaptive module adds monitoring of the population inversion degree of the quantum storage medium. By periodically inserting probe pulses and measuring their absorption linewidth, the coherence time of the medium can be determined. ,when When the degradation rate exceeds 20%, it is determined that the decoherence of the medium is intensifying. The system automatically reduces the control bandwidth to 1 kHz and increases the attenuation coefficient to prevent high-frequency control from exacerbating decoherence. This mechanism significantly extends the effective operating life of the system under medium aging conditions.

[0037] The two implementation methods described above maintain the same core architecture and strictly follow the technical route of intrinsic medium sensing, multi-parameter decoupling and fusion, and collaborative feedback control. They are only optimized and adapted in terms of specific implementation methods according to the application scenario, which fully reflects the universality and scalability of the present invention.

Claims

1. A multi-parameter cooperative feedback stabilization system for lasers used in quantum sensing, characterized in that, include: The intrinsic probe module is used to acquire intrinsic physical quantities related to laser interaction within the quantum storage medium in real time. A multi-parameter error decoupling and fusion module is used to receive signals from the intrinsic probe module of the medium and calculate the cooperative error vector of laser frequency, phase and power relative to the current optimal operating point of the medium. A collaborative feedback control module is used to generate multi-dimensional composite control commands based on the collaborative error vector; The laser actuator module is used to respond to the composite control command and coordinately adjust the frequency, phase and power output of the laser.

2. The multi-parameter cooperative feedback stabilization system for quantum sensing lasers according to claim 1, characterized in that, The intrinsic probe module of the medium includes a quantum state preparation unit, a weak measurement unit, and an intrinsic signal extraction unit; The quantum state preparation unit uses the laser to be stabilized to prepare a reference quantum state that is sensitive to changes in laser parameters in a quantum storage medium. The weak measurement unit performs a non-destructive measurement on the reference quantum state by detecting the fluorescence intensity emitted by the auxiliary energy level coupled to the reference quantum state or by detecting the polarization state rotation angle of the probe light passing through the medium. The intrinsic signal extraction unit receives the output signal from the weak measurement unit and extracts three independent intrinsic error signals, which characterize the actual laser frequency detuning, phase accumulation error, and effective light intensity, through lock-in amplification and digital signal processing.

3. The multi-parameter cooperative feedback stabilization system for quantum sensing lasers according to claim 2, characterized in that, The multi-parameter error decoupling and fusion module includes an error decoupling algorithm unit and an error fusion decision unit; The error decoupling algorithm unit has a built-in medium response Jacobian matrix that has been pre-calibrated through experiments. This matrix describes the linear mapping relationship between the three intrinsic error signals output by the intrinsic probe module and the input disturbances of the three independent control ports of the laser: frequency, phase, and power. The error decoupling algorithm unit decouples the three intrinsic error signals into three independent error components corresponding to the laser frequency control end, phase control end, and power control end by solving the inverse matrix of the Jacobian matrix. The error fusion decision unit receives the three independent error components after decoupling and generates a 3-dimensional collaborative error vector according to the preset error fusion strategy. The error fusion strategy is as follows: when the absolute value of any error component is less than its corresponding first threshold, the component retains its original value in the cooperative error vector; when the absolute value of any error component is greater than or equal to its corresponding first threshold but less than the second threshold, the value of the component in the cooperative error vector is multiplied by a decay coefficient between 0 and 1; when the absolute value of any error component is greater than or equal to its corresponding second threshold, the error fusion decision unit triggers a global relocking protocol, and the cooperative error vector is reset to the initial setting value given by the medium calibration data.

4. The multi-parameter cooperative feedback stabilization system for quantum sensing lasers according to claim 3, characterized in that, The collaborative feedback control module includes a multi-input multi-output controller and an instruction synthesis unit; The multiple input multiple output controller receives a 3-dimensional cooperative error vector from the error fusion decision unit and generates three preliminary control voltages using a state-space feedback control algorithm. The state variables of the state-space feedback control algorithm include the current value of the cooperative error vector and its integral and differential components. The instruction synthesis unit vector superimposes the three preliminary control voltages output by the MIMO controller with programmed scanning instructions or modulation instructions from outside the system to generate the final three composite control instructions.

5. The multi-parameter cooperative feedback stabilization system for quantum sensing lasers according to claim 4, characterized in that, The laser execution module includes a frequency execution unit, a phase execution unit, and a power execution unit; The frequency execution unit receives the frequency control component in the composite control command and uses it to adjust the output light frequency of the laser. The phase execution unit receives the phase control component in the composite control command and uses it to adjust the phase of the laser beam; The power execution unit receives the power control component in the composite control command and uses it to adjust the output power of the laser beam; The response bandwidth of the frequency execution unit, phase execution unit, and power execution unit is more than twice that of the closed-loop bandwidth of the collaborative feedback control module.

6. The multi-parameter cooperative feedback stabilization system for quantum sensing lasers according to claim 5, characterized in that, The weak measurement unit adopts a dual-color light detection scheme; The dual-color light detection scheme involves introducing a weak detection light whose frequency is fixedly detuned to the pump light while preparing the reference quantum state using pump light, and the polarization direction of the detection light is orthogonal to the pump light. The intrinsic signal extraction unit analyzes the magnitude and direction of the polarization state rotation angle of the probe light, and simultaneously demodulates the error information of frequency and phase.

7. The multi-parameter cooperative feedback stabilization system for quantum sensing lasers according to claim 6, characterized in that, The global relock protocol includes a media relaxation wait period with a duration of 10 milliseconds to 100 milliseconds; During the medium relaxation waiting period, the cooperative feedback control module suspends the output of control commands, and the laser execution module maintains the state of the previous moment. After the medium relaxation waiting period ends, the system reinitializes the cooperative error vector based on the medium calibration data and uses a proportional-integral control algorithm for fast coarse locking. Once all error components are below their corresponding first threshold, the system automatically switches back to the normal operation mode of the MIMO controller.

8. The multi-parameter cooperative feedback stabilization system for quantum sensing lasers according to claim 7, characterized in that, The state observer of the state-space feedback control algorithm is implemented using a Kalman filter. The Kalman filter uses the output signal of the intrinsic probe module of the medium and the driving current of the laser actuation module as observation inputs to estimate the state variables that cannot be directly measured inside the system.

9. The multi-parameter cooperative feedback stabilization system for quantum sensing lasers according to claim 1, characterized in that, It also includes a system health monitoring and adaptive module; The system health monitoring and adaptive module monitors in real time the signal-to-noise ratio of the intrinsic probe module, the error vector norm calculated by the multi-parameter error decoupling and fusion module, and the output saturation of the collaborative feedback control module. When the signal-to-noise ratio is detected to be lower than the preset threshold, the error vector norm continues to exceed the warning value, or the time percentage of any control channel output reaching saturation exceeds 5%, the system health monitoring and adaptive module determines that the system health has declined and automatically adjusts the attenuation coefficient in the error fusion decision unit or the integral time constant of the multi-input multi-output controller.

10. The multi-parameter cooperative feedback stabilization system for quantum sensing lasers according to claim 1, characterized in that, The reference quantum state is a coherently populated trapped state or a Raman memory state.

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