Terahertz refractive index-optical rotation common-optical-path joint measurement method and system based on quantum weak value amplification effect, and application of system

Abstract

Disclosed in the present application are a terahertz refractive index-optical rotation common-optical-path joint measurement method and system based on a quantum weak value amplification effect, and an application of the system. The method comprises: performing pre-selection, wherein a polarization state α of an incident terahertz wave emitted by a terahertz time-domain spectral unit is used as a pre-selected quantum state, the polarization state α being selected by means of a first polarizer; performing post-selection, wherein a polarization state α+π2 selected by means of a second polarizer is used as a post-selected quantum state; before measurement, making the post-selected quantum state and the pre-selected quantum state orthogonal to each other; and performing two instances of common-optical-path joint weak coupling, wherein two instances of weak coupling are sequentially performed on the terahertz wave and a sample to be subjected to measurement that is on a common-optical-path joint measurement unit. In the present application, the high-sensitivity characteristic of quantum weak measurement in which a signal is amplified but technical noise is not amplified is used, and by means of common-optical-path joint measurement, the refractive index and optical rotation of a measured chiral drug can be jointly measured with high sensitivity, without the need to change an optical path, thereby realizing high-sensitivity conformation recognition of the chiral drug.

Description

A terahertz refractive index-optical rotation common-path joint detection method, system and application based on quantum weak value amplification effect Technical Field

[0001] The present application relates to the field of terahertz technology. Specifically, the present application relates to a terahertz refractive index-optical rotation common optical path joint detection method, system and application based on quantum weak value amplification effect. Background Art

[0002] Terahertz waves with frequencies in the range of 0.1THz to 10THz have great application potential and significant advantages in the field of biomedical testing due to their excellent properties such as matching the energy levels caused by the vibration, rotation, and conformational changes of macromolecules, good penetration, fingerprint spectrum, and no ionization damage. They have become a current research hotspot at home and abroad.

[0003] Currently mature terahertz time-domain spectroscopy systems have broadband capabilities and are commonly used in laboratory biological detection research. However, direct measurements using this system are not very sensitive, and can only measure one physical quantity at a time (assuming the other physical quantities are known). Accurate measurement of optical rotation is the benchmark for determining the optical rotation of chiral drug enantiomers. However, under the influence of terahertz waves, the left-handed and right-handed isomers of most chiral drugs not only have different optical rotations but also different refractive indices. The two are correlated and coupled, jointly affecting the characteristics of terahertz waves. The concept of quantum weak measurement was first proposed by Aharonov, Albert, and Vaidman (AAV) in 1988. Unlike traditional quantum measurement methods, the detection results of weak measurements can far exceed the eigenvalue spectrum of the observable quantity. This effect is called weak value amplification and has the unique and highly sensitive property of amplifying the signal without amplifying technical noise.

[0004] Therefore, a terahertz refractive index-optical rotation co-path joint detection technology and system based on quantum weak value amplification effect is proposed, which can meet the needs of high-sensitivity co-path joint measurement of refractive index and optical rotation of chiral drugs in the terahertz frequency band.

[0005] Summary of the Invention

[0006] This application provides a terahertz refractive index and optical rotation co-path detection method, system, and application based on the quantum weak value amplification effect, which can solve the problem of the inability to perform high-sensitivity co-path joint measurement of refractive index and optical rotation of chiral drugs in related technologies. The technical solution is as follows:

[0007] According to one aspect of the present application, a terahertz refractive index-optical rotation common-path joint detection method based on the quantum weak value amplification effect is applied to a terahertz refractive index-optical rotation common-path joint detection system based on the quantum weak value amplification effect, the system comprising:

[0008] A first polarizer, a second polarizer, a terahertz time-domain spectroscopy unit, a common optical path joint measurement unit, and a quantum weak value joint detection and calculation unit;

[0009] The method comprises: pre-selecting, by a terahertz time-domain spectroscopy unit, a polarization state α selected by a first polarizer of an incident terahertz wave as a quantum pre-selected state;

[0010] Post-selection, polarization state selected by the second polarizer As a quantum postselected state;

[0011] Before measurement, the quantum post-selected state and the quantum pre-selected state are orthogonal to each other;

[0012] Secondary common optical path joint weak coupling: the terahertz wave and the sample to be measured on the common optical path joint measurement unit are sequentially weakly coupled twice; the terahertz wave parameters are then measured by the terahertz time-domain spectroscopy unit;

[0013] A terahertz quantum weak measurement frequency domain transfer model based on the quantum weak value amplification effect is constructed to calculate the refractive index and optical rotation.

[0014] Preferably, the quantum pre-selected state α→0; the quantum post-selected state

[0015] Preferably, the method of secondary common optical path combined with weak coupling includes the following steps:

[0016] The first weak coupling: the terahertz wave weakly couples with the sample under test in the transmission mode;

[0017] Before the second weak coupling, the polarization state of the terahertz wave is converted from linear polarization to prolate elliptical polarization by the common optical path joint measurement unit;

[0018] The second weak coupling is the weak coupling between the terahertz wave and the sample under test in the metal grating-refraction mode;

[0019] After the second weak coupling, the polarization state of the terahertz wave is converted into linear polarization by the common optical path joint measurement unit.

[0020] Preferably, the terahertz quantum weak measurement frequency domain transfer model based on the quantum weak value amplification effect is: |ψ i >=cosα|H>+sinα|V> (1) |ψ i ′>=cos(α+Δα)|H>+sin(α+Δα)|V> (2)

[0021] |ψ i ″>=cos(α+Δα)|H>+isin(α+Δα)|V> (3) |ψ pre ′>=|Rp |cos(α+Δα)exp(iφ p )|H>+i|R s |sin(α+Δα)exp(iφ s )|V> (4)

[0022] Wherein (1) α is the incident polarization angle (polarization state) of the terahertz wave (in order to generate long elliptically polarized light later, the value of α should be close to zero), |H> and |V> represent the horizontal and vertical polarization states, respectively; (2) Δα is the change in the optical rotation angle; (3) is the expression for the conversion of linear polarization to oblate elliptical polarization; (4) and (5) are the expressions for the polarization state of the terahertz wave after the second weak coupling; (5) R p,s is the generalized Fresnel reflection coefficient of the three-layer prism structure in the horizontal polarization state and the vertical polarization state; where φ p,s is the phase angle of generalized Fresnel reflection, r p,s and r' p,s is the Fresnel reflection coefficient of the interface between the glass film and the thin film sample, θ and k0 are the incident angle and the central wave vector, respectively, and n f and n g are the refractive indices of the metal grating film and prism glass, r' p,s is the refractive index of the sample being measured, and d is the thickness of the metal grating film. Equation (6) expresses the intermediate state in which the orthogonal polarization components of the terahertz wave have different amplitude and phase changes when the refractive index changes slightly during the second weak coupling. In Equation (6), Δ|R p,s | and Δφ p,s Represent the amplitude and phase changes of the parallel polarization state and perpendicular polarization state components respectively. is the polarization operator of the terahertz photon; Δφ=Δφ P -Δφ S ,

[0023] ΔT=(cotα+tanα)Δα,|ψ pre >=|R p |cosαexp(iφ p )|H>+i|R s |sinαexp(iφ s )|V>;

[0024] Equation (7) is the expression of the post-selected terahertz polarization state. In Equation (7), β≈π / 2+Δα is the post-selected polarization angle, and φ is the output phase, which carries the phase difference Δφ=φ between the parallel polarization state and the perpendicular polarization state components. p -φ s Information; (8) is a weak value expression.

[0025] A terahertz refractive index-optical rotation common optical path joint detection system based on quantum weak value amplification effect includes a first polarizer configured to perform terahertz wavefront selection to obtain a quantum pre-selected state;

[0026] a second polarizer configured to perform terahertz wave post-selection to obtain a quantum post-selected state;

[0027] a terahertz time-domain spectroscopy unit configured to emit, adjust, and measure parameters of terahertz waves;

[0028] The common optical path joint measurement unit is configured to perform secondary common optical path joint weak coupling, and the terahertz wave is sequentially weakly coupled to the sample to be measured on the common optical path joint measurement unit for secondary coupling;

[0029] A quantum weak value joint detection and calculation unit is configured to calculate the refractive index and optical rotation based on a terahertz quantum weak measurement frequency domain transfer model of the quantum weak value amplification effect and post-select terahertz wave parameters;

[0030] Preferably, the terahertz time-domain spectroscopy unit has an emitting end and a detecting end, and the first polarizer, the common optical path joint measurement unit and the second polarizer are sequentially arranged between the emitting end and the detecting end;

[0031] The common optical path joint measurement unit includes a sample cell, which is configured as a carrier for the first weak coupling. The sample to be measured is placed in the sample cell, and the terahertz wave is weakly coupled with the sample to be measured in a transmission mode.

[0032] a quarter wave plate 1, configured to convert the linear polarization of the terahertz wave into an oblate elliptical polarization;

[0033] The prism coated with metal grating is configured as a carrier of the second weak coupling. The sample to be tested is placed on the prism coated with metal grating, and the terahertz wave is weakly coupled with the sample to be tested in the metal grating-refraction mode.

[0034] and a quarter wave plate 2, configured to convert the oblate elliptical polarization of the terahertz wave into linear polarization;

[0035] The sample cell, the first quarter wave plate, the prism coated with a metal grating and the second quarter wave plate are sequentially arranged between the first polarizer and the second polarizer.

[0036] Preferably, a half-wave plate and a first lens are sequentially arranged between the emitting end and the first polarizer.

[0037] Preferably, a second lens is arranged between the detection end and the second polarizer.

[0038] Preferably, the terahertz time-domain spectroscopy unit includes a femtosecond laser, a beam splitter, a delay control, several mirrors, a terahertz emission module, a terahertz detection module, a current preamplifier, a lock-in amplifier and a PC.

[0039] Compared with the prior art, this application has the following beneficial effects:

[0040] 1. The present invention utilizes the quantum weak value amplification effect to construct a common optical path mode for the joint measurement of the refractive index and optical rotation of the object being measured on the terahertz time-domain spectroscopy system. Not only can the joint high-sensitivity measurement of the refractive index and optical rotation of the object being measured be achieved without changing the optical path, but its sensitivity will be improved by 2-3 orders of magnitude compared with conventional terahertz time-domain spectroscopy systems.

[0041] 2. Design a terahertz quantum weak measurement mode to achieve quantum weak value amplification at terahertz frequencies, greatly improving detection sensitivity.

[0042] 3. Design a refractive index-optical rotation common-path joint detection mode. On the terahertz time-domain spectroscopy system, construct a transmission and metal grating-refractive common-path combined mode to complete quantum weak coupling and achieve highly sensitive measurement. Without changing the optical path, it has the function of jointly measuring the refractive index and optical rotation of the object being measured.

[0043] 4. Compared with the most commonly used terahertz time-domain spectroscopy system, the terahertz quantum weak measurement system involved in the present invention not only has greatly improved sensitivity and can realize trace detection, but also can jointly measure the refractive index and optical rotation without changing the optical path, which is simple and feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without inventive efforts.

[0045] FIG1 is a schematic diagram of the quantum weak value amplification process according to the present application.

[0046] FIG2 is a diagram showing the mechanism of the terahertz quantum weak value amplification effect according to the present application.

[0047] FIG3 is a schematic diagram of a terahertz refractive index-optical rotation common optical path joint detection system according to an exemplary embodiment of the present application.

[0048] FIG4 is a system block diagram according to an exemplary embodiment of the present application.

[0049] FIG5 is a partial schematic diagram of FIG4.

[0050] FIG6 is a flow chart according to an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0051] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and are not to be construed as limiting the present application.

[0052] It will be understood by those skilled in the art that, unless expressly stated otherwise, the singular forms "a", "an", "said" and "the" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present disclosure refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, "connected" or "coupled" as used herein may include wireless connections or wireless couplings. The term "and / or" used herein includes all or any units and all combinations of one or more associated listed items.

[0053] Please refer to Figure 1 to establish the mechanism of terahertz quantum weak value amplification effect: The mechanism of quantum weak value amplification effect is shown in Figure 1, the pre-selected wave function ψ i (Measured value y0) After weak coupling, the measured value of the wave function ψ' changes slightly by δ, and the wave function ψ is selected f The measured value changes to <y>, which is far away from y0. Using the terahertz photon system as the quantum system to be measured, a terahertz quantum weak measurement system can be constructed, that is, the relationship between the terahertz parameter information and its polarization state can be given; its weak coupling effect refers to the terahertz wave being weakly absorbed, scattered, dispersed or polarized when it is transmitted in the sample by the molecules to be measured; the terahertz spectrum changes (amplitude, phase, broadening, frequency shift, etc.) can be characterized by the filtered post-selected states and ultimately measured by a terahertz detector (spectrometer, power meter, etc.);

[0054] The terahertz quantum weak measurement frequency domain transfer function is thus established: the weak coupling effects of the pre-selected state, post-selected state, and terahertz wave polarization state in the terahertz spectral quantum weak value amplification process are clarified; the weak value expression is derived and analyzed based on the terahertz time-domain spectroscopy system characteristics and device parameters; based on the observed change in the amplified photon momentum (i.e., amplitude and phase) when the measured physical quantity changes slightly, the relationship between the terahertz measured parameters and the measured physical quantity is determined, and the terahertz frequency domain transfer function of quantum weak value amplification is obtained;

[0055] Therefore, a terahertz spectroscopy-quantum weak measurement system is constructed, as shown in Figure 2. The terahertz ≈ 0 polarization state is selected as the pre-selected state, and the π / 2 polarization state is selected as the orthogonal post-selected state; the slight change in the terahertz polarization state caused by the slight change in the optical rotation or refractive index of the chiral molecule is used as the weak coupling effect; the terahertz device and the measured sample are set in the terahertz time-domain spectroscopy system to complete the above three functions, thereby realizing the establishment of the terahertz parameter-quantum weak measurement system.

[0056] Here, a terahertz quantum weak measurement refractive index-optical rotation common optical path joint measurement mode is designed, and the existing terahertz time-domain spectroscopy system is modified and upgraded. A half-wave plate (HWP) is added to the terahertz incident end of the system to adjust the intensity of the incident terahertz wave. A focusing lens (L1) and a linear polarizer (P1) cooperate to obtain a terahertz polarized light with appropriate intensity and an angle of ≈0 with the X direction as the pre-selected state. The second linear polarizer (P2) forms a polarization state with an angle of π / 2-β (β<<1) with the X direction as the post-selected state. The sample to be measured is placed in the sample cell between the two polarizers or on a prism with a metal grating (as shown in Figure 3); on this basis, two 1 / 4 wave plates are added to realize the mutual conversion between linearly polarized light and oblate elliptically polarized light, which can form a common optical path mode for the joint measurement of refractive index and optical rotation, and complete the weak coupling effect of terahertz quantum weak measurement; then the polarizer 2 completes the selection, and the terahertz light focused by the lens 2 enters the electro-optical crystal, Wollaston prism and balanced detector in the terahertz time-domain spectroscopy system, and the terahertz parameter measurement is completed using the electro-optical sampling technology.

[0057] Therefore, a decoupling algorithm between the refractive index and optical rotation of chiral drugs in terahertz quantum weak measurement was implemented, and a terahertz quantum weak measurement amplification experimental platform for the joint measurement of refractive index and optical rotation in a common optical path was built. The sample to be measured was injected into the sample cell in the transmission mode and the same sample to be measured was added to the metal grating surface in the metal grating-refraction mode. The changes in terahertz parameters (such as intensity and phase) after the quantum weak value was measured were obtained. The simultaneous equations were solved to obtain the optical rotation and refractive index of the sample to be measured.

[0058] Finally, they achieved highly sensitive identification of the refractive index and optical rotation of the chiral drug penicillamine. On a terahertz quantum weak measurement refractive index-optical rotation co-path joint measurement experimental platform, they measured the terahertz parameter changes caused by the refractive index and optical rotation of the chiral drug penicillamine without changing the optical path. The refractive index and optical rotation were then calculated using a decoupling algorithm.

[0059] In an exemplary embodiment:

[0060] Referring to FIG4-5 , a terahertz refractive index-optical rotation common optical path joint detection system 100 based on quantum weak value amplification effect includes a first polarizer 101 configured to perform terahertz wavefront selection to obtain a quantum pre-selected state;

[0061] The second polarizer 102 is configured to perform terahertz wave post-selection to obtain a quantum post-selected state;

[0062] The terahertz time-domain spectroscopy unit 103 is configured to emit terahertz waves, adjust and measure terahertz wave parameters;

[0063] The common optical path joint measurement unit 104 is configured to perform secondary common optical path joint weak coupling, and the terahertz wave is sequentially weakly coupled to the sample to be measured on the common optical path joint measurement unit twice;

[0064] The quantum weak value joint detection calculation unit 105 is configured to calculate the refractive index and optical rotation based on the terahertz quantum weak measurement frequency domain transfer model of the quantum weak value amplification effect and the post-selection of terahertz wave parameters;

[0065] In an exemplary embodiment, the terahertz time-domain spectroscopy unit 103 has an emitting end 1031 and a detecting end 1032, and the first polarizer 101, the common optical path joint measurement unit 104 and the second polarizer 102 are sequentially arranged between the emitting end 1031 and the detecting end 1032; the common optical path joint measurement unit 104 includes a sample pool 1041, which is configured as a carrier of the first weak coupling, and the sample to be measured 10 is placed in the sample pool 1041, and the terahertz wave and the sample to be measured 10 are weakly coupled in the transmission mode; the 1 / 4 wave plate 1042 is configured to convert the linear polarization of the terahertz wave into the linear polarization of the terahertz wave; The prism 1043 coated with a metal grating is configured as a carrier of the sample 10 to be tested for a second weak coupling, and the sample 10 to be tested is placed on the prism 1043 coated with a metal grating, and the weak coupling effect between the terahertz wave and the sample 10 to be tested is achieved in the metal grating-refraction mode; and the quarter wave plate 1044 is configured to convert the oblong elliptical polarization of the terahertz wave into linear polarization; the sample cell 1041, the quarter wave plate 1 1042, the prism 1043 coated with a metal grating and the quarter wave plate 1044 are sequentially arranged between the first polarizer 101 and the second polarizer 102.

[0066] In an exemplary embodiment, a half-wave plate 201 and a first lens 202 are sequentially disposed between the transmitting end 1031 and the first polarizer 101 ; and a second lens 203 is disposed between the detecting end 1032 and the second polarizer 102 .

[0067] In an exemplary embodiment, the terahertz time-domain spectroscopy unit 103 includes a femtosecond laser, a beam splitter, a delay control, several mirrors, a terahertz emission module, a terahertz detection module, a current preamplifier, a lock-in amplifier, and a PC.

[0068] Please refer to FIG6 , in an exemplary embodiment, a terahertz refractive index-optical rotation common optical path joint detection system 100 based on the aforementioned quantum weak value amplification effect is applied;

[0069] The method comprises: S1, pre-selection, wherein the polarization state α of the incident terahertz wave emitted by the terahertz time-domain spectroscopy unit is selected by a first polarizer as a quantum pre-selected state;

[0070] S2, post-selection, polarization state selected by the second polarizer As a quantum postselected state;

[0071] Before measurement, the quantum post-selected state and the quantum pre-selected state are orthogonal to each other;

[0072] S3, secondary common optical path joint weak coupling, the terahertz wave and the sample to be measured on the common optical path joint measurement unit are sequentially weakly coupled twice; the terahertz wave parameters are then measured by the terahertz time-domain spectroscopy unit;

[0073] S4. Construct a terahertz quantum weak measurement frequency domain transfer model based on the quantum weak value amplification effect, and calculate the refractive index and optical rotation.

[0074] In an exemplary embodiment, the quantum preselected state α→0; the quantum postselected state The method of secondary common optical path combined with weak coupling includes the following steps:

[0075] The first weak coupling: the terahertz wave weakly couples with the sample under test in the transmission mode;

[0076] Before the second weak coupling, the polarization state of the terahertz wave is converted from linear polarization to prolate elliptical polarization by the common optical path joint measurement unit;

[0077] The second weak coupling is the weak coupling between the terahertz wave and the sample under test in the metal grating-refraction mode;

[0078] After the second weak coupling, the polarization state of the terahertz wave is converted into linear polarization by the common optical path joint measurement unit.

[0079] Frequency domain transfer model of terahertz quantum weak measurement based on quantum weak value amplification effect: |ψ i >=cosα|H>+sinα|V> (1) |ψ i ′>=cos(α+Δα)|H>+sin(α+Δα)|V> (2) |ψ i ″>=cos(α+Δα_|H > +isin(α+Δα)|V> (3) |ψ pre ′>=|R p |cos(α+Δα)exp(iφ p )|H>+i|R s |sin(α+Δα)exp(iφ s )|V> (4)

[0080] Wherein (1) α is the incident polarization angle (polarization state) of the terahertz wave (in order to generate long elliptically polarized light later, the value of α should be close to zero), |H> and |V> represent the horizontal and vertical polarization states, respectively; (2) Δα is the change in the optical rotation angle; (3) is the expression for the conversion of linear polarization to oblate elliptical polarization; (4) and (5) are the expressions for the polarization state of the terahertz wave after the second weak coupling; (5) R p,s is the generalized Fresnel reflection coefficient of the three-layer prism structure in the horizontal polarization state and the vertical polarization state; where φ p,s is the phase angle of generalized Fresnel reflection, r p,s and r' p,s is the Fresnel reflection coefficient of the interface between the glass film and the thin film sample, θ and k0 are the incident angle and the central wave vector, respectively, and n f and n g are the refractive indices of the metal grating film and prism glass, r' p,s is the refractive index of the sample being measured, and d is the thickness of the metal grating film. Equation (6) expresses the intermediate state in which the orthogonal polarization components of the terahertz wave have different amplitude and phase changes when the refractive index changes slightly during the second weak coupling. In Equation (6), Δ|R p,s | and Δφ p,s Represent the amplitude and phase changes of the parallel polarization state and perpendicular polarization state components respectively. is the polarization operator of the terahertz photon; Δφ=Δφ P -Δφ S ,

[0081] ΔT=(cotα+tanα)Δα,|ψ pre >=|R p |cosαexp(iφ p )|H>+ i|R s |sinαexp(iφ s )|V>;

[0082] Equation (7) is the expression of the post-selected terahertz polarization state. In Equation (7), β≈π / 2+Δα is the post-selected polarization angle, and φ is the output phase, which carries the phase difference Δφ=φ between the parallel polarization state and the perpendicular polarization state components. p -φ s Information; (8) is a weak value expression.

[0083] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown in sequence as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some of the steps in the flowcharts of the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0084] The above description is only part of the implementation methods of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.< / y>

Claims

1. A terahertz refractive index-optical rotation common optical path joint detection method based on quantum weak value amplification effect, characterized in that: A terahertz refractive index-optical rotation common optical path joint detection system based on quantum weak value amplification effect is applied, and the system comprises: A first polarizer, a second polarizer, a terahertz time-domain spectroscopy unit, a common optical path joint measurement unit, and a quantum weak value joint detection and calculation unit; The method comprises: pre-selecting, a polarization state α of an incident terahertz wave emitted by a terahertz time-domain spectroscopy unit, selected by a first polarizer, as a quantum pre-selected state; Post-selection, polarization state selected by the second polarizer As a quantum post-selected state; Before measurement, the quantum post-selected state and the quantum pre-selected state are orthogonal to each other; Secondary common optical path joint weak coupling, the terahertz wave and the sample to be measured on the common optical path joint measurement unit are sequentially weakly coupled for the second time, and then the terahertz wave parameters selected after measurement by the terahertz time domain spectroscopy unit; A terahertz quantum weak measurement frequency domain transfer model based on the quantum weak value amplification effect is constructed, and the refractive index and optical rotation are obtained by calculation.

2. The method according to claim 1, characterized in that: The quantum pre-selected state α→0; the quantum post-selected state 3. The method according to claim 2, characterized in that: The method of secondary common optical path combined with weak coupling comprises the following steps: The first weak coupling: the terahertz wave has weak coupling with the sample to be tested in the transmission mode; Before the second weak coupling, the polarization state of the terahertz wave is converted from linear polarization to oblong elliptical polarization by the common optical path joint measurement unit; The second weak coupling is the weak coupling between the terahertz wave and the sample to be measured in the refraction mode; After the second weak coupling, the polarization state of the terahertz wave is converted into linear polarization by the common optical path joint measurement unit.

4. The method according to claim 3, characterized in that: The terahertz quantum weak measurement frequency domain transfer model based on the quantum weak value amplification effect: |ψ i >=cosα|H>+sinα|V> (1) |ψ i ′>=cos(α+Δα)|H>+sin(α+Δα)|V> (2) |ψ i ″>=cos(α+Δα)|H>+isin(α+Δα)|V> (3) |ψ pre >=|R p |cos(α+Δα)exp(iφ p )|H>+i|R s |sin(α+Δα)exp(iφ s )|V> (4) Wherein (1) α is the incident polarization angle (polarization state) of the terahertz wave (in order to generate long elliptically polarized light later, α is preferably close to zero), |H> and |V> represent the horizontal and vertical polarization states respectively; (2) Δα is the change in the optical rotation angle; (3) is the expression for the conversion of linear polarization to oblate elliptical polarization; (4) and (5) are the expressions for the polarization state of the terahertz wave after the second weak coupling; (5) R p,s is the generalized Fresnel reflection coefficient of the three-layer prism structure in the horizontal polarization state and the vertical polarization state; where φ p,s is the generalized Fresnel reflection Phase angle, r p,s and r' p,s is the Fresnel reflection coefficient of the interface between the glass film and the thin film sample, θ and k0 are the incident angle and the central wave vector, respectively, and n f and n g are the refractive indices of the metal grating film and prism glass, r' p,s is the refractive index of the sample under test, d is the thickness of the metal grating film; (6) is the expression for the intermediate state in which the orthogonal polarization components of the terahertz wave have different amplitude and phase changes when the refractive index changes slightly in the second weak coupling; (6) where Δ|R p,s | and Δφ p,s Represent the amplitude and phase changes of the parallel polarization state and perpendicular polarization state components respectively. is the polarization operator of the terahertz photon; Df=Df P -Df S , ΔT=(cotα+tanα)Δα,|ψ pre >=|R p |cosαexp(iφ p )|H>+i|R s |sinαexp(iφ s )|V>; Formula (7) is the expression of the post-selected THz polarization state. In formula (7), β≈π / 2+Δα is the post-selected polarization angle, φ is the output phase, and the phase difference Δφ=φ between the parallel polarization state and the perpendicular polarization state components is p -φ s Information; (8) is a weak value expression.

5. A terahertz refractive index-optical rotation common optical path joint detection system based on quantum weak value amplification effect, characterized in that: It includes a first polarizer configured to perform terahertz wavefront selection to obtain a quantum pre-selected state; a second polarizer configured to perform terahertz wave post-selection to obtain a quantum post-selected state; A terahertz time-domain spectroscopy unit is configured to emit terahertz waves, adjust and measure terahertz wave parameters; The common optical path joint measurement unit is configured as a secondary common optical path joint weak coupling, and the terahertz wave and the sample to be measured on the common optical path joint measurement unit are sequentially weakly coupled twice; The quantum weak value joint detection calculation unit is configured to calculate the refractive index and optical rotation based on the terahertz quantum weak measurement frequency domain transfer model of the quantum weak value amplification effect and the post-selection of terahertz wave parameters.

6. The system according to claim 5, characterized in that: The terahertz time-domain spectroscopy unit has a transmitting end and a detecting end, and a first polarizer, a common optical path joint measurement unit and a second polarizer are sequentially arranged between the transmitting end and the detecting end; The common optical path joint measurement unit includes a transmission sample carrier configured as a first weak coupling carrier, the sample to be measured is placed in the transmission sample carrier, and the terahertz wave and the sample to be measured are weakly coupled in the transmission mode; A quarter wave plate 1, configured to convert the linear polarization of the terahertz wave into an oblate elliptical polarization; A refraction sample carrier is configured as a second weak coupling carrier, and the sample to be tested is placed on the refraction sample carrier, and a terahertz wave is weakly coupled with the sample to be tested in a refraction mode; and a quarter wave plate 2, configured to convert the oblate elliptical polarization of the terahertz wave into a linear polarization; The transmission sample carrier, the first quarter wave plate, the refraction sample carrier and the second quarter wave plate are sequentially arranged between the first polarizer and the second polarizer.

7. The system according to claim 6, characterized in that: The transmission sample carrier is a sample cell, and the refraction sample carrier is a prism coated with a metal grating.

8. The system according to claim 6, characterized in that: A half-wave plate and a lens 1 are sequentially arranged between the emitting end and the first polarizer.

9. The system according to claim 6, characterized in that: A second lens is arranged between the detection end and the second polarizer.

10. The system according to claim 6, characterized in that: The terahertz time-domain spectroscopy unit includes a femtosecond laser, a beam splitter, a delay control, a plurality of reflectors, a terahertz emission module, a terahertz detection module, a current preamplifier, a phase-locked amplifier and a PC.

11. Use of the system according to claims 6-10 in the combined detection of the refractive index and optical rotation of chiral drugs.

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