Time-varying parameter real-time estimation method and system based on weak measurement technology

Abstract

The application provides a time-varying parameter real-time estimation method and system based on a weak measurement technology, comprising the following steps: step 1, a quantum weak measurement optical platform for time-varying parameter real-time estimation is built, and an external signal is introduced in the weak coupling process to generate a time-varying phase parameter; step 2, the light intensity difference is received by a balanced detector, and the current phase is calculated; step 3, the reference phase is adjusted according to the current phase, so that the system works in a preset sensitivity and dynamic range; step 4, steps 2 and 3 are repeatedly executed to realize real-time estimation of the time-varying phase; and step 5, after the measurement is completed, the estimation result is processed according to actual needs. The application can not only realize high-precision real-time estimation of the time-varying parameter, but also has adjustable sensitivity and dynamic range, and can adaptively place the weak measurement in the required sensitivity and dynamic working interval.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of weak measurement, in particular to a time-varying parameter real-time estimation method and system based on weak measurement technology. BACKGROUND

[0002] Quantum sensing is a measurement of physical quantities with higher sensitivity and accuracy by using quantum systems or quantum resources, and its two most important features are strong response to the signal of interest and minimization of unwanted noise interference. Generally, quantum sensing can be divided into four processes: preparation of pointer state, parameterization of the signal of interest, reading of the final state and classical statistical processing. For many practical applications, such as quantum navigation, quantum radar, etc., the signal of interest is usually unknown, random and time-varying. Therefore, time-varying parameter estimation is a potential and challenging task in quantum sensing.

[0003] Patent document CN109726825A (application number: CN201811556730.4) discloses a method and system for compensating parameter estimation deviation in weak measurement, comprising: cutting off the physical source of the to-be-measured parameter in the weak measurement process, setting the to-be-measured parameter τ to 0, and obtaining the parameter estimation deviation value Δτ caused by noise through weak measurement; based on the obtained parameter estimation deviation value, adjusting the parameters of the machine learning model through training and testing, establishing a machine learning model for fitting the change trend of the parameter deviation; and performing weak measurement parameter estimation in the case of normal measurement of the to-be-measured parameter, and estimating and correcting the parameter estimation deviation value at the current time using the machine learning model.

[0004] In the field of quantum sensing, weak measurement technology has achieved precision and sensitivity that cannot be achieved by classical means in the observation of spin Hall effect, phase change, time delay change and other parameter estimation of light, and has good suppression effect on technical noise. However, when applying weak measurement technology for time-varying parameter estimation, the response time of the optical spectrum detection method is relatively long, which limits the change speed of the time-varying parameter, and in practice, the size of the parameter may have a strong interaction with the measured system, which cannot meet the weak measurement condition. The above reasons may be the key obstacles to the widespread and complex practical application of weak measurement. SUMMARY

[0005] In view of the defects in the prior art, the purpose of the present application is to provide a time-varying parameter real-time estimation method and system based on weak measurement technology.

[0006] The time-varying parameter real-time estimation method based on weak measurement technology provided by the present application comprises:

[0007] Step 1: build a quantum weak measurement optical platform for real-time estimation of time-varying parameters, and introduce an external signal in the weak coupling process to generate a time-varying phase parameter;

[0008] Step 2: receive the light intensity difference through the balanced detector and calculate the current phase;

[0009] Step 3: adjust the reference phase according to the current phase to make the system work within the preset sensitivity and dynamic range;

[0010] Step 4: repeat steps 2 and 3 to realize real-time estimation of the time-varying phase;

[0011] Step 5: after the measurement is completed, perform data processing on the estimated results according to actual needs.

[0012] Preferably, the step 1 comprises:

[0013] Step 1.1: modulate the light output by the light source into a pre-selected state |i>;

[0014] Step 1.2: the signal to be measured enters the weak measurement system and is encoded into a time-varying phase parameter The interaction is represented as Wherein, is the observable of the system, and the state of the output light after the interaction is represented as

[0015] Step 1.3: the light after weak coupling is divided into two paths through a beam splitter, the first path passes through the beam splitter, and the second path passes through the beam splitter and a mirror, and the output state of the two paths is |Φ i >;

[0016] Step 1.4: increase the reference phase with adaptive adjustment in the two paths respectively And The introduced reference phase is represented as

[0017] Step 1.5: modulate the two paths of the post-selection state, respectively denoted as |f1> and |f2>, and the post-selection angles are ε 1,2 , respectively. Project the light after the phase parameter adjustment of the two paths into the post-selection state.

[0018] Preferably, the two paths of light have opposite post-selection angles and reference phases, i.e.:

[0019] Preferably, the step 2 comprises:

[0020] Weak measurement is performed using light intensity as the detection index, and the light intensity of the two output paths is represented as Wherein, I0 is the initial light intensity;

[0021] The difference of the two light intensities is detected by a balanced detector. When the weak measurement condition is met, the measurement value wherein, is a weak value, ImA w is the imaginary part of the weak value, and the estimation of the time-varying phase is further realized.

[0022] Preferably, the step 3 comprises:

[0023] Step 3.1: Set the adjustment threshold according to the actual needs and

[0024] Step 3.2: Compare the estimated value of the current phase with the adjustment threshold and to determine the dynamic range in which the weak measurement system is located, wherein t j is the current time, and j is the serial number.

[0025] Step 3.3: Adjust the reference phase according to the current dynamic range. If increase the reference phase so that the measurement is located in a lower sensitivity and a larger dynamic range interval; if then decrease the reference phase so that the measurement is located in a higher sensitivity and a smaller dynamic range interval; if then directly proceed to the next measurement.

[0026] According to the time-varying parameter real-time estimation system based on the weak measurement technology provided by the application, comprising:

[0027] Module M1: Build a quantum weak measurement optical platform for real-time estimation of time-varying parameters, and introduce an external signal in the weak coupling process to generate a time-varying phase parameter;

[0028] Module M2: Receive the difference in light intensity through a balanced detector and calculate the current phase;

[0029] Module M3: Adjust the reference phase according to the current phase to make the system work in a preset sensitivity and dynamic range;

[0030] Module M4: Repeat the calling of module M2 and module M3 to realize real-time estimation of the time-varying phase;

[0031] Module M5: After the measurement is completed, perform data processing on the estimation results according to actual needs.

[0032] Preferably, the module M1 comprises:

[0033] Module M1.1: modulate the light outputted by the light source into a pre-selected state |i>;

[0034] Module M1.2: the signal to be measured enters the weak measurement system and is encoded into a time-varying phase parameter The interaction is represented as wherein, is the observable of the system, and the state of the output light after the interaction is represented as

[0035] Module M1.3: the light after weak coupling is divided into two paths by a beam splitter, the first path passes through the beam splitter, and the second path passes through the beam splitter and a mirror, and the output states of the two paths are both |Φ i >;

[0036] Module M1.4: respectively adding an adaptively adjusted reference phase to the two paths and The introduced reference phase is represented as

[0037] Module M1.5: modulating the two post-selected states, respectively denoted as |f1> and |f2>, and the post-selection angles are respectively ε 1,2 Projecting the light after the parametric phase adjustment of the two paths into the post-selected states respectively.

[0038] Preferably, the two paths of light have opposite post-selection angles and reference phases, i.e.,

[0039] Preferably, the module M2 comprises:

[0040] Using light intensity as a detection index for weak measurement, the light intensity outputted by the two paths is represented as wherein, I0 is the initial light intensity;

[0041] Using a balanced detector to detect the difference between the light intensities of the two paths, when the weak measurement condition is met, the measurement value wherein, is a weak value, and ImA w is the imaginary part of the weak value, and the estimation of the time-varying phase is further realized.

[0042] Preferably, the module M3 comprises:

[0043] Module M3.1: setting an adjustment threshold according to actual requirements and

[0044] Module M3.2: according to the estimated value of the current phase and the adjustment threshold and Comparison is made to determine the dynamic range in which the weak measurement system is located, wherein t j t is the current time, and j is the serial number.

[0045] Module M3.3: Adjust the reference phase according to the current dynamic range, if the reference phase is increased to place the measurement in a lower sensitivity, larger dynamic range interval; if the reference phase is decreased to place the measurement in a higher sensitivity, smaller dynamic range interval; if the next measurement is directly performed.

[0046] Compared with the prior art, the present application has the following beneficial effects:

[0047] (1) The present application not only enables high-precision real-time estimation of time-varying parameters, but also has adjustable sensitivity and dynamic range, and can adaptively place weak measurement in the required sensitivity and dynamic working interval;

[0048] (2) The present application has simple structure and is easy to use, which makes up for the defects of the prior art;

[0049] (3) The present application expands the application scenarios of numerous measurement systems based on weak measurement theory. BRIEF DESCRIPTION OF DRAWINGS

[0050] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the accompanying drawings:

[0051] Figure 1 is a schematic diagram of the principle of the present application;

[0052] Figure 2 is a flowchart of the adaptive adjustment of the reference phase of the present application;

[0053] In the figure, 1 is a light source; 2 is a pre-selection process; 3 is a weak coupling process; 4 is a beam splitter; 5 is a mirror; 6 is a first reference phase; 7 is a second reference phase; 8 is a first post-selection process; 9 is a second post-selection process; 10 is a balanced detector; and 11 is a computer. DETAILED DESCRIPTION

[0054] The present application will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present application. These all belong to the protection scope of the present application.

[0055] Embodiment:

[0056] High-precision time-varying parameter estimation has important applications in many practical applications. Since the weak measurement technology is proposed, it has achieved the precision and sensitivity that classical methods cannot achieve in the estimation of spin Hall effect, phase change, time delay change and other parameters of observation light, and has good suppression effect on technical noise. However, when the weak measurement technology is applied to time-varying parameter estimation, the response time of the optical spectrum detection method is long, which limits the change speed of the time-varying parameter, and in practice, the size of the parameter may have a strong interaction with the measured system, which cannot meet the weak measurement condition. The above reasons may be the key obstacles to the wide and complex practical application of weak measurement. The purpose of the present application is to provide a high-precision real-time estimation method for time-varying phase based on quantum weak measurement theory, which has adjustable sensitivity and dynamic range.

[0057] As shown in Figure 1 The present application provides a high-precision real-time estimation method for time-varying phase based on quantum weak measurement theory, which comprises a light source 1, a pre-selection process 2, a weak coupling process 3, a beam splitter 4, a mirror 5, a first reference phase 6, a second reference phase 7, a first post-selection process 8, a second post-selection process 9, a balanced detector 10 and a computer 11.

[0058] The light emitted by the light source 1 passes through the pre-selection process 2, then the phase caused by the external signal in the weak coupling process 3, and then is divided into two paths by the beam splitter 4; the first path of light passes through the first reference phase 6 for phase adjustment, and the second path of light passes through the mirror 5, then passes through the second reference phase 7 for phase adjustment, and then passes through the second post-selection process 9; finally, the two beams of light are received by the balanced detector 10 for intensity detection and data processing, and the first reference phase 6, the second reference phase 7 and the balanced detector 10 are respectively connected to the computer 11. The method comprises the following steps:

[0059] Step A: build a quantum weak measurement optical platform for real-time estimation of time-varying parameters, and introduce an external signal in the weak coupling process 3 to generate a time-varying phase parameter;

[0060] Step B: calculate the current phase according to the light intensity difference received by the balanced detector 10;

[0061] Step C: adjust the first reference phase 6 and the second reference phase 7 according to the current phase, so that the system works in a better sensitivity and dynamic range;

[0062] Step D: repeat steps B and C to realize real-time estimation of the time-varying phase;

[0063] Step E: after the measurement is completed, the estimated results are processed according to actual needs.

[0064] Wherein, the step A comprises the following steps:

[0065] Step A1: pre-selection step: the light output by the light source is modulated into a pre-selected state |i>;

[0066] Step A2: weak coupling step: the signal to be measured enters the weak measurement system and is encoded into a time-varying phase parameter The interaction can be represented as Wherein, is the observable of the system, and the state of the output light after the interaction can be represented as

[0067] Step A3: the light after weak coupling is divided into two paths through a beam splitter, the first path passes through the beam splitter, and the second path passes through the beam splitter and a mirror, and the output states of the two paths are both |Φ i >;

[0068] Step A4: reference phase adjustment, in order to make the system have adjustable sensitivity and dynamic range, respectively increase the self-adaptive reference phase in the two paths and The introduced reference phase is represented as

[0069] In steps A3 and A4, in order to facilitate calculation, the two paths of light need to have opposite post-selection angles and reference phases, that is: ε 1,2 =±ε,

[0070] Step A5: modulate the two post-selection states, respectively denoted as |f1> and |f2>, and the post-selection angles are respectively ε 1,2 Project the two paths of light after parametric phase adjustment into the post-selection states respectively.

[0071] Wherein, the step B considers that the sampling frequency needs to meet the Nyquist theorem in signal sampling, and the light intensity detection can detect signals of higher frequency. Preferably, light intensity is used as a detection index for weak measurement. In theory, the light intensity of the two output paths can be represented as Wherein, I0 is the initial light intensity. The balanced detector is used to detect the difference between the light intensities of the two paths, and when the weak measurement condition is met, the measurement value Wherein, Aw1,2=f1,2|U1,2(tj)A|if1,2U1,2tji=±Aw is the weak value, and ImAw is the imaginary part of the weak value, and then the estimation of the time-varying phase is realized.

[0072] Wherein, the step C has a flow chart as Figure 2 shown, comprising the following steps:

[0073] Step C1: Threshold Setting Step: Set the adjustment threshold according to actual needs. and

[0074] In step C1, to improve the sensitivity of the measurement results, the threshold is adjusted. It should be slightly smaller than the upper limit of the dynamic linear range; to avoid the minimum detection intensity of the balance detector and measurement errors affecting the phase estimation value, a threshold is set.

[0075] Step C2: Judgment Step: Based on the estimated value of the current phase With adjustment threshold and By comparing, we can determine the dynamic range of the weak measurement system, where t j Let j be the current time and j be the sequence number;

[0076] Step C3: Adjust the reference phase according to the current dynamic range. Increase reference phase To make the measurement fall within a range of lower sensitivity and a larger dynamic range; if Then reduce the reference phase This allows the measurement to be performed within a higher sensitivity and a smaller dynamic range; if Then proceed directly to the next measurement.

[0077] The real-time estimation system for time-varying parameters based on weak measurement technology provided by the present invention includes: Module M1: constructing a quantum weak measurement optical platform for real-time estimation of time-varying parameters, and introducing external signals during weak coupling to generate time-varying phase parameters; Module M2: receiving light intensity difference through a balanced detector and calculating the current phase; Module M3: adjusting the reference phase according to the current phase to make the system work within a preset sensitivity and dynamic range; Module M4: repeatedly calling modules M2 and M3 to realize real-time estimation of the time-varying phase; Module M5: after the measurement is completed, performing data processing on the estimation results according to actual needs.

[0078] The module M1 includes: module M1.1: modulating the light output from the light source into a pre-selected state |i>; module M1.2: the signal to be measured enters the weak measurement system and is encoded into a time-varying phase parameter. Interactions are represented as in, For observable measurements of the system, the state of the output light after interaction is represented as follows: Module M1.3: Splits the weakly coupled light into two paths using a beam splitter. The first path passes through the beam splitter, and the second path passes through the beam splitter and a reflector. Both paths output in the form of |Φ. iModule M1.4: increase the reference phase respectively in two paths and The introduced reference phase is expressed as Module M1.5: modulate the post-selection states of two paths, respectively denoted as |f1> and |f2>, and the post-selection angles are respectively ε 1,2 Project the two paths after parametric phase adjustment to the post-selection states respectively.

[0079] The two paths have opposite post-selection angles and reference phases, that is: ε 1,2 = ±ε,

[0080] The module M2 includes: weak measurement is carried out by using light intensity as a detection index, and the light intensity of two outputs is expressed as Wherein, I0 is the initial light intensity; the difference between the light intensity of two paths is detected by using a balanced detector, and when the weak measurement condition is met, the measurement value Wherein, is a weak value, and ImA w is the imaginary part of the weak value, and then the estimation of time-varying phase is realized.

[0081] The module M3 includes: module M3.1: set the adjustment threshold according to actual requirements and Module M3.2: compare the estimated value of the current phase with the adjustment threshold and to determine the dynamic range in which the weak measurement system is located, wherein t j is the current time, and j is the serial number; module M3.3: adjust the reference phase according to the dynamic range in which it is currently located, if increase the reference phase so that the measurement is located in a lower sensitivity and a larger dynamic range interval; if then decrease the reference phase so that the measurement is located in a higher sensitivity and a smaller dynamic range interval; if then directly perform the next measurement.

[0082] Those skilled in the art know that, in addition to implementing the system, device and each module thereof provided by the present application in the form of pure computer readable program code, the same program can also be implemented in the form of logic gate, switch, special integrated circuit, programmable logic controller and embedded microcontroller, etc. by logically programming the method steps. Therefore, the system, device and each module thereof provided by the present application can be considered as a hardware component, and the modules included therein for implementing various programs can also be considered as structures in the hardware component; the modules for implementing various functions can also be considered as both software programs for implementing methods and structures in the hardware component.

[0083] The specific embodiments of the present application are described above. It needs to be understood that the present application is not limited to the specific embodiments described above, and various changes or modifications can be made by those skilled in the art within the scope of the claims, which does not affect the essential content of the present application. The embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily without conflict.

Claims

1. A method for real-time estimation of time-varying parameters based on weak measurement technique, characterized in that, The method comprises the following steps: Step 1: build a quantum weak measurement optical platform for real-time estimation of time-varying parameters, and introduce an external signal in the weak coupling process to generate a time-varying phase parameter; Step 2: receive the light intensity difference through a balanced detector and calculate the current phase; Step 3: adjust the reference phase according to the current phase to make the system work within the preset sensitivity and dynamic range; Step 4: repeatedly execute steps 2 and 3 to realize real-time estimation of the time-varying phase; Step 5: after the measurement is completed, data processing is performed on the estimated results according to actual needs; The step 1 comprises: Step 1.1: Modulating light output by a light source into a preselected state ; Step 1.2: The signal to be measured enters the weak measurement system and is encoded into a time-varying phase parameter , the interaction is represented as , where is the observable of the system, and the state of the output light is represented as ; Step 1.3: The light passing through the weak coupling is divided into two paths by a beam splitter, the first path passes through the beam splitter, and the second path passes through the beam splitter and a mirror, and the states of the output light of the two paths are ; Step 1.4: Reference phase adaptation in two paths and The interaction after introducing the reference phase is represented as ; Step 1.5: Modulate the two paths of the post-selected state, respectively denoted as and with a post-selection angle of Project the two paths of the light after parametric phase modulation to the post-selected state; The two light paths have opposite back selection angles and reference phases, i.e.: , ; The step 2 comprises: The light intensity is used as a detection index for weak measurement, and the light intensity of two output paths is represented as wherein, is an initial light intensity; The difference between the two light intensities is detected by a balanced detector. When the weak measurement condition is met, the measurement value wherein, is a weak value, is an imaginary part of the weak value, is a current time, is a serial number.

2. The time-varying parameter real-time estimation method based on weak measurement technology according to claim 1, characterized in that, The step 3 comprises: Step 3.1: Set the adjustment threshold according to the actual needs and ; Step 3.2: Based on the estimated value of the current phase , and adjustment threshold and By comparing, the dynamic range of the weak measurement system is determined, where... For the current moment, For serial number; Step 3.3: Adjust the reference phase according to the now prevailing dynamic range, if the reference phase is increased ; if the reference phase is decreased ; if the next measurement is taken directly.

3. A time-varying parameter real-time estimation system based on weak measurement technique, characterized in that, The method comprises the following steps: Module M1: build a quantum weak measurement optical platform for real-time estimation of time-varying parameters, and introduce an external signal in the weak coupling process to generate a time-varying phase parameter; Module M2: receive the light intensity difference through a balanced detector and calculate the current phase; Module M3: adjust the reference phase according to the current phase to make the system work within the preset sensitivity and dynamic range; Module M4: repeatedly call modules M2 and M3 to realize real-time estimation of the time-varying phase; Module M5: after the measurement is completed, data processing is performed on the estimated results according to actual needs; The module M1 comprises: Module M1.1: Modulating light output by a light source into a preselected state ; Module M1.2: The signal to be measured enters the weak measurement system and is encoded into a time-varying phase parameter , the interaction is represented as , where is the observable of the system, and the state of the output light after the interaction is represented as ; Module M1.3: Divides the weakly coupled light into two paths by a beam splitter, the first path passes through the beam splitter, and the second path passes through the beam splitter and a mirror, and the output state of both paths is ; Module M1.4: Adding adaptive adjustment of the reference phase in both paths, respectively and The interaction after introducing the reference phase is represented as ; Module M1.5: modulating two paths of post-selection states, respectively denoted as and , the post-selection angle is , respectively projecting the two paths of light after parametric phase adjustment to the post-selection states; The two light paths have opposite back selection angles and reference phases, i.e.: , ; The module M2 comprises: The light intensity is used as a detection index for weak measurement, and the light intensity of two output paths is represented as wherein, is an initial light intensity; The difference between the two light intensities is detected by a balanced detector. When the weak measurement condition is met, the measurement value wherein, is a weak value, is an imaginary part of the weak value, is a current time, is a serial number.

4. The time-varying parameter real-time estimation system based on weak measurement technology according to claim 3, characterized in that, The module M3 comprises: Module M3.1 : Setting the adjustment threshold according to actual needs and ; Module M3.2: comparing the estimate of the current phase with a regulation threshold and judging the dynamic range in which the weak measurement system is located, wherein and the regulation threshold is a function of the sequence number is the current time instant, is the sequence number; Module M3.3: Adjust the reference phase according to the dynamic range in which we are now, if the reference phase is increased ; if the reference phase is decreased ; if , the next measurement is directly performed.

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