Phase demodulation method and system in weak measurement system

Abstract

The present invention provides a phase demodulation method and system for a weak-phase measurement system, comprising: Step 1: constructing a fully polarization-maintaining quantum weak-phase measurement optical system using polarization-maintaining fiber; Step 2: generating a carrier wave in the optical phase through internal modulation using a frequency-tunable laser; Step 3: performing light intensity detection using a dual-path light intensity detection structure; and Step 4: receiving the optical signal via a balanced detector and demodulating it using a phase demodulation algorithm to obtain amplified phase information. This method can overcome signal fluctuations caused by low-frequency slow-drift signals or slow-drift initial phases due to environmental vibrations, temperature, and other factors, achieving high-precision and high-sensitivity measurement of time-varying parameters.

Description

Technical Field

[0001] The present invention relates to the field of weak measurement technology, and in particular to a phase demodulation method and system in a weak measurement system. Background Art

[0002] Quantum sensing exploits the properties of quantum mechanics to overcome the limitations of classical sensing and circumvent the Heisenberg uncertainty principle, enabling more sensitive and accurate measurements of physical quantities. Its performance far surpasses that of classical sensing in many technological applications. Weak measurement, as a quantum measurement, differs from strong measurement in that it minimally perturbs the system and can only obtain limited quantum state information. However, when preselection and postselection work together, weak measurement can achieve astonishing results far exceeding the eigenvalues. Since its discovery by Aharonov et al. in 1988, weak measurement has been applied to various fields and yielded numerous research results, most notably the ultra-sensitive measurement of the spin Hall effect. Despite the significant advancements in the application of weak measurement technology, current research primarily focuses on the high-precision detection of a single weak physical quantity. Addressing the adverse effects of phase drift caused by the external environment and the initial phase drift on phase demodulation has been understudied. To expand the practical application of weak measurement technology, it is necessary to eliminate the effects of initial phase drift and environmental factors on the detection sensitivity of weak measurement systems. Therefore, a signal detection method suitable for weak measurement systems is one approach to address this issue.

[0003] Patent document CN111811636A (application number: CN202010719439.5) discloses a broadband vibration measurement system and method for a multi-wavelength weak anti-structure sensing fiber. The first measurement system includes a multi-wavelength weak anti-structure sensing fiber and a multi-wavelength light source. The multi-wavelength light source is sequentially connected to the first port of a first wavelength division multiplexer, an acousto-optic modulator, an optical amplifier, and a circulator. The second port and the third port of the circulator are respectively connected to the multi-wavelength weak anti-structure sensing fiber and the second wavelength division multiplexer; the output of the second wavelength division multiplexer is connected to a phase demodulation module. The second measurement system includes a multi-wavelength weak anti-structure sensing fiber and a pulsed light source. The pulsed light source is connected to the first port of several circulators, the second port of each circulator is connected to the multi-wavelength weak anti-structure sensing fiber, and the third ports of all circulators are connected to the phase demodulation module. However, this patent cannot solve the existing technical problems and cannot meet the needs of the present invention. Summary of the Invention

[0004] In view of the defects in the prior art, an object of the present invention is to provide a phase demodulation method and system in a weak measurement system.

[0005] The phase demodulation method in a weak measurement system provided by the present invention includes:

[0006] Step 1: Use polarization-maintaining fiber to build a fully polarization-maintaining quantum weak measurement optical system;

[0007] Step 2: Generate a carrier in the optical phase by internal modulation of a frequency-tunable laser;

[0008] Step 3: Use a dual-path light intensity detection structure to perform light intensity detection;

[0009] Step 4: Receive the optical signal through a balanced detector and demodulate it through a phase demodulation algorithm to obtain the amplified phase information.

[0010] Preferably, the step 1 comprises:

[0011] Step 1.1: The light transmission fibers in the quantum weak measurement optical system are all made of polarization-maintaining fibers. The high birefringence of polarization-maintaining fibers is used to keep the polarization state of light stable, thus suppressing the introduction of polarization noise.

[0012] Step 1.2: The pre-selected state of the weak measurement system is selected as the 45° linear polarization state, represented by |i>; the measured signal introduced in the interaction Low-frequency slow drift signals caused by vibration and temperature in the environment Respectively expressed as and in It is one of the Pauli operators, |H> and |V> represent the horizontal and vertical polarization states, respectively.

[0013] Preferably, step 2 includes: the interferometer in the system is a non-equal arm structure, assuming that the interferometer arm length difference is l, the optical fiber refractive index is n, and the optical frequency is cosine modulation v0cosω0t, where v0 is the optical frequency modulation amplitude and ω0 is the light source modulation angular frequency, then the phase modulation generated by the interferometer is: Expressed as in is the modulation depth; t is the modulation time; n=1,2; c is the speed of light.

[0014] Preferably, step 3 includes: the system uses two post-selection optical paths to perform light intensity detection, and both post-selections select a polarization state that is orthogonal to the pre-selection state and differs by a small angle ε, the difference being that one is +ε and the other is -ε, which are represented by |f1> and |f2> respectively;

[0015] The output light intensity is expressed as: Where I0 is the initial light intensity, specifically:

[0016]

[0017]

[0018] in is the initial phase;

[0019] The modulated optical phase includes the zero frequency, first harmonic frequency and infinite high-order harmonic frequency of the carrier signal frequency ω0. As k increases, the kth order Bessel function J k The overall trend of (C) becomes smaller, and the first and second frequencies of the carrier signal are selected for correlation detection during detection.

[0020] Preferably, step 4 includes:

[0021] Step 4.1: Perform differential calculation on the dual-path light intensity. The expression is:

[0022]

[0023]

[0024] in

[0025] Step 4.2: Select the single frequency and double frequency of the carrier signal for correlation detection, that is, multiply ΔI1 and ΔI2 by Gcosω0t and Hcos2ω0t respectively, and pass through low-pass filtering, then:

[0026] ΔI1 part:

[0027]

[0028]

[0029] ΔI2 part:

[0030]

[0031]

[0032] Step 4.3: After differentiating the two components (3) and (4) of the ΔI2 part, we get:

[0033]

[0034]

[0035] Step 4.4: Cross-multiply and subtract the four components (3), (4), (5), and (6), i.e. (4) × (5) - (3) × (6), and we get:

[0036]

[0037] Step 4.5: Pass the above components (7) through the integrator, and we have:

[0038]

[0039] Step 4.6: Cross-multiply and subtract the four components (1), (2), (3), and (4), i.e., (2) × (3) - (1) × (4), to obtain:

[0040] GHABJ1(C)J2(C) (31)

[0041] Step 4.7: Divide the above two components (8) and (9) by a divider, i.e. (8) ÷ (9), and we get:

[0042]

[0043] Step 4.8: Pass the above component (10) through a high-pass filter to obtain:

[0044]

[0045] The signal to be measured is demodulated without distortion, and the coefficients are amplified by a factor of cot2ε.

[0046] The phase demodulation system in the weak measurement system provided by the present invention includes:

[0047] Module M1: Use polarization-maintaining fiber to build a fully polarization-maintaining quantum weak measurement optical system;

[0048] Module M2: Generates a carrier wave in the optical phase by internal modulation of a frequency-tunable laser;

[0049] Module M3: uses a dual-path light intensity detection structure for light intensity detection;

[0050] Module M4: Receives the optical signal through a balanced detector and demodulates it through a phase demodulation algorithm to obtain the amplified phase information.

[0051] Preferably, the module M1 includes:

[0052] Module M1.1: The light transmission fibers in the quantum weak measurement optical system are all made of polarization-maintaining fibers. The high birefringence of polarization-maintaining fibers is used to stabilize the polarization state of light and suppress the introduction of polarization noise.

[0053] Module M1.2: The preselected state of the weak measurement system is selected as the 45° linear polarization state, represented by |i>; the measured signal introduced in the interaction Low-frequency slow drift signals caused by vibration and temperature in the environment Respectively expressed as and in is one of the Pauli operators, |H> and |V> represent the horizontal and vertical polarization states, respectively.

[0054] Preferably, the module M2 includes: the interferometer in the system is a non-equal arm structure, assuming that the interferometer arm length difference is l, the optical fiber refractive index is n, and the optical frequency is cosine modulation v0cosω0t, where v0 is the optical frequency modulation amplitude and ω0 is the light source modulation angular frequency, then the phase modulation generated by the interferometer is: Expressed as in is the modulation depth; t is the modulation time; n=1,2; c is the speed of light.

[0055] Preferably, the module M3 includes: the system uses two post-selection optical paths for light intensity detection, and the two post-selection paths both select a polarization state that is orthogonal to the pre-selection state and differs by a small angle ε, the difference being that one is +ε and the other is -ε, which are represented by |f1> and |f2> respectively;

[0056] The output light intensity is expressed as: Where I0 is the initial light intensity, specifically:

[0057]

[0058]

[0059] in is the initial phase;

[0060] The modulated optical phase includes the zero frequency, first harmonic frequency and infinite high-order harmonic frequency of the carrier signal frequency ω0. As k increases, the kth order Bessel function J k The overall trend of (C) becomes smaller, and the first and second frequencies of the carrier signal are selected for correlation detection during detection.

[0061] Preferably, the module M4 includes:

[0062] Module M4.1: Perform differential calculation on the dual-path light intensity. The expression is:

[0063]

[0064]

[0065] in

[0066] Module M4.2: Select the single and double frequencies of the carrier signal for correlation detection. That is, multiply ΔI1 and ΔI2 by G cos ω0t and H cos 2ω0t respectively, and pass them through low-pass filtering. Then:

[0067] ΔI1 part:

[0068]

[0069]

[0070] ΔI2 part:

[0071]

[0072]

[0073] Module M4.3: After the two components (3) and (4) of the ΔI2 part are passed through the differentiator, we have:

[0074]

[0075]

[0076] Module M4.4: Cross-multiply and subtract the four components (3)(4)(5)(6), i.e. (4)×(5)-(3)×(6), and we get:

[0077]

[0078] Module M4.5: Pass the above components (7) through the integrator, and we have:

[0079]

[0080] Module M4.6: Cross-multiply and subtract the four components (1), (2), (3), and (4), i.e., (2) × (3) - (1) × (4), to obtain:

[0081] GHABJ1(C)J2(C) (42)

[0082] Module M4.7: Divide the two components (8) and (9) above by a divider, i.e. (8)÷(9), and we get:

[0083]

[0084] Module M4.8: Pass the above component (10) through a high-pass filter to obtain:

[0085]

[0086] The signal to be measured is demodulated without distortion, and the coefficients are amplified by a factor of cot2ε.

[0087] Compared with the prior art, the present invention has the following beneficial effects:

[0088] (1) The present invention overcomes the signal fluctuation caused by low-frequency slow drift signals or slow drift of initial phase due to vibration, temperature, etc. in the environment;

[0089] (2) The present invention achieves high-precision and high-sensitivity measurement of time-varying parameters;

[0090] (3) The present invention ensures good consistency of passband sensitivity;

[0091] (4) The present invention increases the applicability of weak measurement technology in practical scenario applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0093] Figure 1 A flow chart of the steps of a phase demodulation algorithm in a weak measurement system of the present invention;

[0094] Figure 2 It is a system structure diagram of the present invention;

[0095] The figure shows:

[0096] Light source 1 Second coupling head 8

[0097] Pre-selection 2 First post-selection process 9

[0098] First coupling head 3 First balanced detector 10

[0099] Optical fiber PBS 4 third coupling head 11

[0100] First reflector 5 Second post-selection process 12

[0101] Second reflecting mirror 6 Second balanced detector 13

[0102] Fiber BS 7 Phase Demodulation Algorithm 14 DETAILED DESCRIPTION

[0103] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0104] Example 1:

[0105] like Figure 1 This embodiment provides a phase demodulation algorithm in a fiber-based weak measurement system, including:

[0106] Step 1: Use polarization-maintaining fiber to build a fully polarization-maintaining quantum weak measurement optical system to keep the polarization state of light stable during transmission and reduce the introduction of polarization noise;

[0107] Step 2: Generate a carrier wave in the optical phase by internal modulation using a frequency-tunable laser. This requires the interferometer in the system to have a non-equal-arm structure. Compared to external modulation, internal modulation reduces the introduction of electrical components and is more conducive to system integration and array formation.

[0108] Step 3: Using a dual-path light intensity detection structure can achieve more efficient detection;

[0109] Step 4: The optical signal is received by a balanced detector and demodulated by a phase demodulation algorithm to obtain the amplified phase information, achieving high-sensitivity and high-linearity detection.

[0110] The step 1 comprises:

[0111] Step 1.1: The light-transmitting fibers in the quantum weak measurement optical system are all made of polarization-maintaining fibers. The high birefringence of polarization-maintaining fibers is used to keep the polarization state of light stable, thereby suppressing the introduction of polarization noise.

[0112] Step 1.2: The pre-selected state of the weak measurement system is selected as the 45° linear polarization state, represented by |i>; the measured signal introduced in the interaction Low-frequency slow drift signals caused by vibration, temperature, etc. in the environment Respectively expressed as and in It is one of the Pauli operators, |H> and |V> represent the horizontal and vertical polarization states, respectively.

[0113] Step 2 includes: the system generates a carrier in the optical phase through a frequency-tunable laser, which requires the interferometer in the system to have a non-equal arm structure. Assuming the interferometer arm length difference is l, the fiber refractive index is n, and the optical frequency is cosine modulated v0cosω0t, where v0 is the optical frequency modulation amplitude and ω0 is the light source modulation angular frequency, the phase modulation generated by the interferometer is Expressed as in is the modulation depth.

[0114] The step 3 includes: the system adopts a dual-path post-selection optical path for light intensity detection. Compared with the spectral detection of classical weak measurement, the single detection time of light intensity detection is extremely low, and the detection of time-varying parameters can be achieved at a higher frequency, which can be applied to more application scenarios.

[0115] Both post-selections select polarization states that are orthogonal to the pre-selected state but differ by a tiny angle ε. The difference is that one is +ε and the other is -ε, represented as |f1> and |f2> respectively.

[0116] The output light intensity is expressed as: Where I0 is the initial light intensity. Specifically:

[0117]

[0118]

[0119] in The initial phase.

[0120] The modulated optical phase includes the zero frequency, first harmonic frequency and infinite high harmonic frequency of the carrier signal frequency ω0. As k increases, the kth order Bessel function J k The overall trend of (C) becomes smaller, and the carrier signal's single frequency and double frequency can be used for relevant detection during detection.

[0121] The step 4 comprises:

[0122] Step 4.1: Perform differential calculation on the dual-path light intensity, namely:

[0123]

[0124]

[0125] in

[0126] Step 4.2: Select the single frequency and double frequency of the carrier signal for correlation detection, that is, multiply ΔI1 and ΔI2 by Gcosω0t and Hcos2ω0t respectively, and pass through low-pass filtering, then:

[0127] ΔI1 part:

[0128]

[0129]

[0130] ΔI2 part:

[0131]

[0132]

[0133] Step 4.3: After differentiating the two components (3) and (4) of the ΔI2 part, we get:

[0134]

[0135]

[0136] Step 4.4: Cross-multiply and subtract the four components (3), (4), (5), and (6), i.e. (4) × (5) - (3) × (6), and we get:

[0137]

[0138] Step 4.5: Pass the above components (7) through the integrator, and we have:

[0139]

[0140] Step 4.6: Cross-multiply and subtract the four components (1), (2), (3), and (4), i.e., (2) × (3) - (1) × (4), to obtain:

[0141] GHABJ1(C)J2(C) (53)

[0142] Step 4.7: Divide the above two components (8) and (9) by a divider, i.e. (8) ÷ (9), and we get:

[0143]

[0144] Step 4.8: Pass the above component (10) through a high-pass filter to obtain:

[0145]

[0146] The signal to be measured is demodulated without distortion, and the coefficients are amplified by a factor of cot2ε.

[0147] Example 2:

[0148] like Figure 2 As shown, the phase demodulation system in the optical fiber-based weak measurement system provided by this embodiment includes: a light source 1, a pre-selection 2, a first coupling head 3, an optical fiber PBS 4, a first reflector 5, a second reflector 6, an optical fiber BS 7, a second coupling head 8, a first post-selection process 9, a first balanced detector 10, a third coupling head 11, a second post-selection process 12, a second balanced detector 13 and a phase demodulation algorithm 14.

[0149] The light source 1 modulates the optical frequency according to the setting, and the light wave is modulated into a specific polarization state through the pre-selection process 2. At the first coupling head 3, the light enters the polarization-maintaining optical fiber from the free space, and the light is divided into H light and V light at the optical fiber PBS 4. The light is then reflected back by the first reflector 5 and the second reflector 6, and combined at the optical fiber PBS 4. The phase to be measured is introduced by the optical path difference of the Michelson interferometer; the combined light is split into two paths at the optical fiber BS 7, and the two light paths enter the free space from the optical fiber through the second coupling head 8 and the third coupling head 11 respectively, and then respectively undergo projection measurement through the first post-selection process 9 and the second post-selection process 12, and finally are received and detected by the first balanced detector 10 and the second balanced detector 13; the two detected output lights are finally sent to the phase demodulation algorithm 14 for analysis and processing to obtain the amplified signal to be measured.

[0150] The phase demodulation system in the optical fiber-based weak measurement system provided in this embodiment includes the following modules:

[0151] Module M1: Use polarization-maintaining fiber to build a fully polarization-maintaining quantum weak measurement optical system to keep the polarization state of light stable during transmission and reduce the introduction of polarization noise;

[0152] Module M2: Generates a carrier wave in the optical phase through internal modulation of a frequency-tunable laser. This requires the interferometer in the system to have a non-equal-arm structure. Compared to external modulation, internal modulation reduces the number of electrical components and is more conducive to system integration and array formation.

[0153] Module M3: adopts dual-path light intensity detection structure, which can achieve more efficient detection;

[0154] Module M4: Receives optical signals through a balanced detector and demodulates them using a phase demodulation algorithm to obtain amplified phase information, achieving high-sensitivity and high-linearity detection.

[0155] The module M1 includes:

[0156] Module M1.1: The light transmission fibers in the quantum weak measurement optical system are all made of polarization-maintaining fibers. The high birefringence of polarization-maintaining fibers is used to stabilize the polarization state of light and suppress the introduction of polarization noise.

[0157] Module M1.2: The pre-selected state of the weak measurement system is selected as the 45° linear polarization state, expressed as |i>; the measured signal introduced in the interaction Low-frequency slow drift signals caused by vibration, temperature, etc. in the environment Respectively expressed as and in It is one of the Pauli operators, |H> and |V> represent the horizontal and vertical polarization states, respectively.

[0158] The module M2 includes: the system generates a carrier in the optical phase through a frequency-tunable laser, which requires the interferometer in the system to have a non-equal arm structure. Assuming the interferometer arm length difference is l, the fiber refractive index is n, and the optical frequency is cosine modulated v0cosω0t, where v0 is the optical frequency modulation amplitude and ω0 is the light source modulation angular frequency, the phase modulation generated by the interferometer is Expressed as in is the modulation depth.

[0159] The module M3 includes: the system adopts a dual-path post-selection optical path for light intensity detection. Compared with the spectral detection of classical weak measurement, the single detection time of light intensity detection is extremely low, and the detection of time-varying parameters can be achieved at a higher frequency, which can be applied to more application scenarios.

[0160] Both post-selections select polarization states that are orthogonal to the pre-selected state but differ by a tiny angle ε. The difference is that one is +ε and the other is -ε, represented as |f1> and |f2> respectively.

[0161] The output light intensity is expressed as: Where I0 is the initial light intensity. Specifically:

[0162]

[0163]

[0164] in The initial phase.

[0165] The modulated optical phase includes the zero frequency, first harmonic frequency and infinite high harmonic frequency of the carrier signal frequency ω0. As k increases, the kth order Bessel function J k The overall trend of (C) becomes smaller, and the carrier signal's single frequency and double frequency can be used for relevant detection during detection.

[0166] The module M4 includes:

[0167] Module M4.1: Perform differential calculation on the dual-path light intensity, namely:

[0168]

[0169]

[0170] in

[0171] Module M4.2: Select the single and double frequencies of the carrier signal for correlation detection. That is, multiply ΔI1 and ΔI2 by G cos ω0t and H cos 2ω0t respectively, and pass them through low-pass filtering. Then:

[0172] ΔI1 part:

[0173]

[0174]

[0175] ΔI2 part:

[0176]

[0177]

[0178] Module M4.3: After the two components (3) and (4) of the ΔI2 part are passed through the differentiator, we have:

[0179]

[0180]

[0181] Module M4.4: Cross-multiply and subtract the four components (3)(4)(5)(6), i.e. (4)×(5)-(3)×(6), and we get:

[0182]

[0183] Module M4.5: Pass the above components (7) through the integrator, and we have:

[0184]

[0185] Module M4.6: Cross-multiply and subtract the four components (1), (2), (3), and (4), i.e., (2) × (3) - (1) × (4), to obtain:

[0186] GHABJ1(C)J2(C) (64)

[0187] Module M4.7: Divide the two components (8) and (9) above by a divider, i.e. (8)÷(9), and we get:

[0188]

[0189] Module M4.8: Pass the above component (10) through a high-pass filter to obtain:

[0190]

[0191] The signal to be measured is demodulated without distortion, and the coefficients are amplified by a factor of cot2ε.

[0192] The present invention can overcome signal fluctuations caused by low-frequency slow drift signals or slow drift of initial phases due to vibration, temperature, etc. in the environment, and achieve high-precision and high-sensitivity measurement of time-varying parameters.

[0193] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0194] Those skilled in the art will appreciate that, in addition to implementing the system, device, and various modules provided by the present invention in purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, and the like by logically programming the method steps. Therefore, the system, device, and various modules provided by the present invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; the modules for implementing various functions can also be considered both software programs for implementing the method and structures within the hardware component.

[0195] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A phase demodulation method in a weak measurement system, characterized in that: include: Step 1: Use polarization-maintaining fiber to build a fully polarization-maintaining quantum weak measurement optical system; Step 2: Generate a carrier in the optical phase by internal modulation of a frequency-tunable laser; Step 3: Use a dual-path light intensity detection structure to perform light intensity detection; Step 4: Receive the optical signal through the balanced detector and demodulate it through the phase demodulation algorithm to obtain the amplified phase information; The step 3 includes: the system uses two post-selection optical paths to detect light intensity, and the two post-selection paths both select polarization states that are orthogonal to the pre-selection state and differ by a small angle ε, the difference being that one is +ε and the other is -ε, which are represented by |f1> and |f2> respectively; The output light intensity is expressed as: Where I0 is the initial light intensity, specifically: in is the initial phase; The modulated optical phase includes the zero frequency, first harmonic frequency and infinite high-order harmonic frequency of the carrier signal frequency ω0. As k increases, the kth order Bessel function J k The overall trend of (C) becomes smaller, and the first and second frequencies of the carrier signal are selected for correlation detection during detection.

2. The phase demodulation method in a weak measurement system according to claim 1, characterized in that: The step 1 comprises: Step 1.1: The light transmission fibers in the quantum weak measurement optical system are all made of polarization-maintaining fibers. The high birefringence of polarization-maintaining fibers is used to keep the polarization state of light stable, thus suppressing the introduction of polarization noise. Step 1.2: The pre-selected state of the weak measurement system is selected as the 45° linear polarization state, represented by |i>; the measured signal introduced in the interaction Low-frequency slow drift signals caused by vibration and temperature in the environment Respectively expressed as and in is one of the Pauli operators, |H> and |V> represent the horizontal and vertical polarization states, respectively.

3. The phase demodulation method in a weak measurement system according to claim 2, characterized in that: The step 2 includes: the interferometer in the system has a non-equal arm structure, assuming that the interferometer arm length difference is I, the optical fiber refractive index is n, and the optical frequency is cosine modulation v0cosω0t, where v0 is the optical frequency modulation amplitude and ω0 is the light source modulation angular frequency, then the phase modulation generated by the interferometer is: Expressed as in is the modulation depth; t is the modulation time; n=1,2; c is the speed of light.

4. The phase demodulation method in a weak measurement system according to claim 3, characterized in that: The step 4 comprises: Step 4.1: Perform differential calculation on the dual-path light intensity. The expression is: in Step 4.2: Select the single frequency and double frequency of the carrier signal for correlation detection, that is, multiply ΔI1 and ΔI2 by Gcosω0t and Hcos2ω0t respectively, and pass through low-pass filtering, then: ΔI1 part: ΔI2 part: Step 4.3: After differentiating the two components (3) and (4) of the ΔI2 part, we get: Step 4.4: Cross-multiply and subtract the four components (3), (4), (5), and (6), i.e. (4) × (5) - (3) × (6), and we get: Step 4.5: Pass the above components (7) through the integrator, and we have: Step 4.6: Cross-multiply and subtract the four components (1), (2), (3), and (4), i.e., (2) × (3) - (1) × (4), to obtain: GHABJ1(C)J2(C)(9) Step 4.7: Divide the above two components (8) and (9) by a divider, i.e. (8) ÷ (9), and we get: Step 4.8: Pass the above component (10) through a high-pass filter to obtain: The signal to be measured is demodulated without distortion, and the coefficients are amplified by a factor of cot2ε.

5. A phase demodulation system in a weak measurement system, characterized in that: include: Module M1: Use polarization-maintaining fiber to build a fully polarization-maintaining quantum weak measurement optical system; Module M2: Generates a carrier wave in the optical phase by internal modulation of a frequency-tunable laser; Module M3: uses a dual-path light intensity detection structure for light intensity detection; Module M4: Receives the optical signal through a balanced detector and demodulates it using a phase demodulation algorithm to obtain the amplified phase information; The module M3 includes: the system uses two post-selection optical paths to detect light intensity, and the two post-selection paths both select polarization states that are orthogonal to the pre-selection state and differ by a small angle ε, the difference being that one is +ε and the other is -ε, represented by |f1> and |f2> respectively; The output light intensity is expressed as: Where I0 is the initial light intensity, specifically: in is the initial phase; The modulated optical phase includes the zero frequency, first harmonic frequency and infinite high-order harmonic frequency of the carrier signal frequency ω0. As k increases, the kth order Bessel function J k The overall trend of (C) becomes smaller, and the first and second frequencies of the carrier signal are selected for correlation detection during detection.

6. The phase demodulation system in the weak measurement system according to claim 5, characterized in that: The module M1 includes: Module M1.1: The light transmission fibers in the quantum weak measurement optical system are all made of polarization-maintaining fibers. The high birefringence of polarization-maintaining fibers is used to stabilize the polarization state of light and suppress the introduction of polarization noise. Module M1.2: The preselected state of the weak measurement system is selected as the 45° linear polarization state, represented by |i>; the measured signal introduced in the interaction Low-frequency slow drift signals caused by vibration and temperature in the environment Respectively expressed as and in is one of the Pauli operators, |H> and |V> represent the horizontal and vertical polarization states, respectively.

7. The phase demodulation system in the weak measurement system according to claim 6, characterized in that: The module M2 includes: the interferometer in the system is a non-equal arm structure, assuming that the interferometer arm length difference is I, the optical fiber refractive index is n, and the optical frequency is cosine modulation v0cosω0t, where v0 is the optical frequency modulation amplitude and ω0 is the light source modulation angular frequency. Then the phase modulation generated by the interferometer is: Expressed as in is the modulation depth; t is the modulation time; n=1,2; c is the speed of light.

8. The phase demodulation system in the weak measurement system according to claim 5, characterized in that: The module M4 includes: Module M4.1: Perform differential calculation on the dual-path light intensity. The expression is: in Module M4.2: Select the frequency doubling and frequency doubling of the carrier signal for correlation detection. That is, multiply ΔI1 and ΔI2 by Gcosω0t and Hcos2ω0t respectively, and pass through low-pass filtering. Then: ΔI1 part: ΔI2 part: Module M4.3: After the two components (3) and (4) of the ΔI2 part are passed through the differentiator, we have: Module M4.4: Cross-multiply and subtract the four components (3)(4)(5)(6), i.e. (4)×(5)-(3)×(6), and we get: Module M4.5: Pass the above components (7) through the integrator, and we have: Module M4.6: Cross-multiply and subtract the four components (1), (2), (3), and (4), i.e., (2) × (3) - (1) × (4), to obtain: GHABJ1(C)J2(C)(9) Module M4.7: Divide the two components (8) and (9) above by a divider, i.e. (8)÷(9), and we get: Module M4.8: Pass the above component (10) through a high-pass filter to obtain: The signal to be measured is demodulated without distortion, and the coefficients are amplified by a factor of cot2ε.

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