Method and system for high-sensitivity detection of trace substances based on terahertz quantum weak measurement technology and application

Abstract

The invention relates to a method and a system for high-sensitivity detection of trace substances based on a terahertz quantum weak measurement technology and application. The method comprises the following steps: transmitting: a terahertz transmitting end outputs terahertz waves; pre-selection: screening a terahertz photon polarization state alpha through a first polaroid as a pre-selection state of the system; post-selection: screening a terahertz photon polarization state beta through a second polaroid to serve as a post-selection state of the system; weak coupling: placing a sample carrier loaded with a to-be-tested sample between a first polaroid and a second polaroid, and after the terahertz waves interact with the to-be-tested sample, receiving an output signal selected after terahertz photons pass through the second polaroid by a terahertz detection end for testing; and calculating: constructing a terahertz quantum weak measurement transmission model, and calculating and analyzing the physical properties of the to-be-tested sample loaded on the sample carrier according to the selected output signal. By means of the arrangement, high-sensitivity detection of trace substances is achieved.

Description

Technical Field

[0001] The present invention relates to the field of terahertz technology, and in particular to a method, system and application for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology. Background Art

[0002] Trace substance detection aims to accurately detect and analyze substances with extremely low content in samples. Although these substances are present in very small amounts, they may have a significant impact in many fields, such as biomedicine, environmental monitoring, food safety, etc. Trace substance detection is quite difficult because its content is extremely small, conventional detection methods are difficult to capture its signal, and it is easily interfered by complex matrices, which increases the complexity of accurate detection.

[0003] Terahertz, as an electromagnetic wave with a frequency ranging from 0.1 to 10 THz, is located in the transition band between traditional electronics and photonics. It has excellent characteristics such as low electron energy and high time and spatial resolution. In particular, the rotation and vibration energy levels of many biological macromolecules and chemical substances are in the terahertz frequency band, which has attracted widespread attention in the non-destructive detection of biological materials such as amino acids, proteins and cells.

[0004] However, when using terahertz waves to detect trace biochemical substances, traditional terahertz detection methods, such as time-domain spectroscopy, have extremely weak detection signals, insufficient detection sensitivity, and extremely low signal-to-noise ratio of the system due to the limited interaction distance between the terahertz waves and the target detection object, making it difficult to meet the needs of high-precision detection of trace biochemical substances. Summary of the invention

[0005] In order to solve the defect of insufficient sensitivity of the current terahertz technology for detecting trace substances, the present invention proposes a method, system and application for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology.

[0006] The technical solution adopted by the present invention is a method for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology, which is applied to a system for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology. The system includes: a terahertz transmitting end, a first polarizer, a sample carrier, a second polarizer, a terahertz detection end, and a terahertz quantum weak measurement calculation and analysis unit. The method includes:

[0007] Transmitting, the terahertz transmitting end outputs a terahertz wave, and the terahertz wave passes through the first polarizer, the sample carrier, the second polarizer, and the terahertz detection end in sequence;

[0008] Pre-selection, screening the polarization state α of the terahertz photon through the first polarizer as the pre-selected state of the system;

[0009] Post-selection: screening the polarization state β of the terahertz photon through the second polarizer as the post-selected state of the system;

[0010] Weak coupling, placing the sample carrier loaded with the sample to be tested between the first polarizer and the second polarizer, after the terahertz wave interacts with the sample to be tested, the output signal of the terahertz photons selected by the second polarizer is received and tested by the terahertz detection end;

[0011] Calculate and construct a terahertz quantum weak measurement transmission model, and calculate and analyze the physical properties of the sample to be tested loaded on the sample carrier according to the output signal after the post-selection.

[0012] Furthermore, before detection, the pre-selected state and post-selected state of the system are close to orthogonal.

[0013] Further, the calculation and analysis of the physical properties of the sample to be tested loaded on the sample carrier specifically includes:

[0014] Calculating the change in output terahertz wave intensity caused by the change in the physical properties of the sample to be tested;

[0015] The output terahertz wave intensity variation reflects the physical quantity of the sample to be tested;

[0016] The output terahertz wave intensity variation is attributed to a physical quantity of the sample to be measured, and the physical quantity includes one of a refractive index, an optical rotation, or a combined effect of the refractive index and the optical rotation.

[0017] Furthermore, the target physical quantity of the sample to be measured is the refractive index, and the interaction mode between the terahertz wave and the sample to be measured is a transmission transmission mode or a reflection transmission mode.

[0018] Furthermore, the terahertz quantum weak measurement transmission model is:

[0019]

[0020]

[0021] Wherein, α in formula (1) is the polarization state of the incident terahertz wave, |H> and |V> represent the horizontal and vertical polarization states respectively; formula (2) represents the system pre-selected state when the sample state does not change. When it is in the transmission mode, |A p,s | and Represent the amplitude and phase of the transfer function respectively. When it is the reflection transmission mode, |A p,s | and represent the generalized Fresnel reflection coefficient and phase angle respectively; Formula (3) represents the intermediate state of the system when the sample refractive index changes, where ΔA=Δ|A p | / |A p |-Δ|A s | / ||A s |; Formula (4) represents the post-selection state of the system, β is the post-selection angle; Formula (5) represents the system output signal strength; Formula (6) represents the initial state signal strength when the sample state does not change; Formula (7) represents the system weak value; Formula (8) represents the signal intensity contrast when the sample refractive index changes, that is, the ratio of the signal intensity change caused by the change in the sample refractive index to the initial state signal intensity, which can be used as the accuracy indicator of the detection method. The above theoretical model needs to satisfy ΔA / 2<<1 and

[0022] Furthermore, the target physical quantity of the sample to be measured is optical rotation, and the interaction mode between the terahertz wave and the sample to be measured is a transmission mode.

[0023] Furthermore, the terahertz quantum weak measurement transmission model is:

[0024]

[0025]

[0026] Wherein, formula (9) represents the system pre-selection state, |+>=(|H>+i|V>) / 2 and |->=(|H>-i|V><) / 2 represent left-handed circularly polarized light and right-handed circularly polarized light, |H> and |V> represent horizontal and vertical polarization states, respectively; formula (10) represents the intermediate state after weak coupling; formula (11) represents the system post-selection state, β is the post-selection angle; formula (12) represents the system output signal intensity; formula (13) represents the output signal intensity when the sample state does not change; formula (14) represents the system weak value; formula (15) represents the signal intensity contrast when the sample optical rotation changes, that is, the ratio of the signal intensity change caused by the change in the sample optical rotation to the initial state signal intensity, which can be used as the accuracy indicator of the detection method. The above theoretical model needs to meet

[0027] Furthermore, the target physical quantity of the sample to be measured is the comprehensive effect of the refractive index and the optical rotation, and the interaction mode between the terahertz wave and the sample to be measured is a transmission mode.

[0028] Furthermore, the terahertz quantum weak measurement transmission model is:

[0029]

[0030]

[0031] Wherein, formula (16) represents the pre-selected state of the system, |H> and |V> represent the horizontal and vertical polarization states respectively; formula (17) represents the intermediate state after weak coupling; formula (18) represents the post-selected state of the system, β is the post-selected angle; formula (19) represents the output signal intensity of the system; formula (20) represents the system output when the sample state does not change; formula (21) represents the weak value of the system; formula (22) represents the signal intensity contrast when the refractive index and optical rotation of the sample change, that is, the ratio of the signal intensity change caused by the change of the refractive index and optical rotation of the sample to the initial state signal intensity, which can be used as the accuracy index of the detection method. The above theoretical model needs to satisfy ΔA / 2<<1 and

[0032] The present invention also discloses a system for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology, and adopts the method for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology. The system comprises:

[0033] A terahertz transmitter, which outputs terahertz waves;

[0034] A first polarizer, which is arranged between the terahertz emission end and the sample carrier, pre-selects the polarization state of the terahertz photons to construct a pre-selected state of the system;

[0035] A sample carrier, which is arranged between the first polarizer and the second polarizer, and the sample to be tested loaded on the sample carrier has a weak interaction with the terahertz photons;

[0036] A second polarizer is disposed between the sample carrier and the terahertz detection end to screen the terahertz photons after interacting with the sample to be measured, so as to construct a post-selection state of the system;

[0037] A terahertz detection end receives the output signal after pre-selection, weak coupling and post-selection;

[0038] The terahertz quantum weak measurement calculation and analysis unit calculates the terahertz wave intensity change and the target physical quantity of the sample to be measured based on the terahertz quantum weak measurement transmission model and the post-selection output signal.

[0039] Furthermore, the interaction mode between the terahertz wave and the sample to be tested is a transmission transmission mode or a reflection transmission mode. In the reflection transmission mode, the refractive index parameters of the sample to be tested can be detected and characterized. In the transmission transmission mode, the refractive index, optical rotation, or the combined effect of the refractive index and optical rotation of the sample to be tested can be detected and characterized.

[0040] The invention also discloses an application of the system in the detection of trace biochemical samples.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The method of the present invention for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology uses the advantage of quantum weak measurement technology in amplifying signals without amplifying noise. The method constructs the pre-selected state and post-selected state of the system based on the polarization characteristics of terahertz photons. When the state of the sample to be detected changes slightly, the sample to be detected interacts weakly with the system to be detected, thus achieving highly sensitive detection of trace substances;

[0043] 2. Establishing a terahertz quantum weak measurement transmission model and clarifying its weak value amplification mechanism are important supports for building a highly sensitive detection system for trace substances based on terahertz quantum weak measurement technology and its system application;

[0044] 3. In the transmission mode and reflection transmission mode, the physical parameters of the sample refractive index and optical rotation can be accurately characterized;

[0045] 4. The invention relates to a highly sensitive detection method for trace substances based on terahertz quantum weak measurement technology. Compared with the existing terahertz detection method, the theoretical test accuracy can be improved by up to 10 orders of magnitude. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention is described in detail below with reference to the embodiments and accompanying drawings, wherein:

[0047] Figure 1 It is a system that can detect trace substances with high sensitivity based on terahertz quantum weak measurement technology in transmission mode;

[0048] Figure 2 It is a system that uses terahertz quantum weak measurement technology in reflection transmission mode to perform highly sensitive detection of trace substances.

[0049] Figure 3 It is the detection result of the sample refractive index parameters by the existing terahertz method in the transmission mode;

[0050] Figure 4 It is a method for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology in transmission mode to detect the refractive index parameters of samples;

[0051] Figure 5 It is the detection result of the sample refractive index parameters by the existing terahertz method in the reflection transmission mode;

[0052] Figure 6 It is a method for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology in reflection transmission mode to detect the refractive index parameters of samples;

[0053] Figure 7It is the result of detecting the optical rotation of the sample by the existing terahertz method in the transmission mode;

[0054] Figure 8 It is a method for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology in transmission mode to detect the optical rotation of samples;

[0055] Fig. 9 It is the detection result of the comprehensive effect of sample refractive index and optical rotation by the existing terahertz method in the transmission mode;

[0056] Fig.10 It is a method for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology in transmission mode, and detects the comprehensive effects of sample refractive index and optical rotation;

[0057] Fig.11 The present invention is a flow chart of a method for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology.

[0058] 10. Terahertz emission end; 20. First polarizer; 30. Sample carrier; 40. Second polarizer; 50. Terahertz detection end. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical scheme and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar components or components with 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 invention, and cannot be interpreted as limiting the present invention.

[0060] In one embodiment, a method for high-sensitivity detection of trace substances based on terahertz quantum weak measurement technology is applied to a system for high-sensitivity detection of trace substances based on terahertz quantum weak measurement technology, the system including a terahertz transmitting end 10, a first polarizer 20, a sample carrier 30, a second polarizer 40, a terahertz detection end 50, and a terahertz quantum weak measurement calculation and analysis unit. The components work together to build a complete detection system, aiming to achieve accurate detection of trace substances.

[0061] See also Fig.11 , methods for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology include:

[0062] S1. Transmitting. The terahertz transmitting end outputs terahertz waves, which pass through the first polarizer, the sample carrier, the second polarizer, and the terahertz detection end in sequence. The terahertz transmitting end acts as a signal source and outputs terahertz waves in a specific frequency range (0.1-10THz). The terahertz wave, as an information carrier, lays the foundation for subsequent interaction with the sample and the detection process. Terahertz waves have the characteristics of low electron energy, high temporal and spatial resolution, can interact specifically with trace substances, and their propagation characteristics in the medium are affected by the physical properties of the sample, which makes detection possible.

[0063] S2, pre-selection, the terahertz photon polarization state α is screened by the first polarizer as the pre-selected state of this system. When the terahertz wave propagates to the first polarizer, based on the principle of polarizer screening the polarization state of light, only terahertz photons with a specific polarization state α can pass through. This screening process realizes the setting of the initial state of the quantum system, ensures the consistency and repeatability of the detection process, and provides a unified starting condition for subsequent precise measurements. In the framework of quantum mechanics, the selection of a specific polarization state has a key impact on the evolution of subsequent quantum states and measurement results.

[0064] S3, post-selection, the terahertz photon polarization state β is screened by the second polarizer as the post-selection state of this system. The terahertz photon continues to propagate to the second polarizer, where the terahertz photon with polarization state β is screened. The pre-selection state α and the post-selection state β jointly define the measurement range of the quantum system. By cleverly designing these two polarization states, the system's ability to respond to weak signals of trace substances can be enhanced. In quantum measurement theory, the appropriate selection of pre- and post-selection states can effectively amplify the measurement signal and improve measurement accuracy.

[0065] S4, weak coupling, placing the sample carrier loaded with the sample to be tested between the first polarizer and the second polarizer. After the terahertz wave interacts with the sample to be tested, the output signal of the terahertz photon after post-selection by the second polarizer is received and tested by the terahertz detection end. The sample carrier carrying the sample to be tested is placed between two polarizers, and the terahertz wave interacts with the sample to be tested with weak coupling. This weak coupling effect minimizes interference with the sample state while allowing the terahertz wave to carry the physical information of the sample. For example, the properties of the sample such as the refractive index and optical rotation will change the propagation characteristics of the terahertz wave, including its intensity, phase, polarization state, etc. After interacting with the sample, the terahertz photon continues to propagate to the second polarizer, and the output signal after post-selection is received by the terahertz detection end. The terahertz detection end converts the optical signal into an electrical signal for subsequent analysis and processing.

[0066] S5. Calculate and construct a terahertz quantum weak measurement transmission model. According to the output signal after post-selection, calculate and analyze the physical properties of the sample to be tested loaded on the sample carrier. The terahertz quantum weak measurement calculation and analysis unit constructs a terahertz quantum weak measurement transmission model. The model is based on the principles of quantum mechanics and the theory of the interaction between terahertz waves and matter, and takes into account various physical effects of terahertz waves in the propagation process, such as absorption, scattering, polarization changes, etc. By inputting the output signal after post-selection, the model can accurately calculate and analyze the physical properties of the sample to be tested loaded on the sample carrier. This calculation and analysis process comprehensively considers the pre- and post-selection states of the quantum system, the interaction between the terahertz wave and the sample, and various physical factors in the transmission process, thereby achieving highly sensitive detection of the physical properties of trace substances.

[0067] A method for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology in this embodiment uses the advantage of quantum weak measurement technology that it amplifies signals without amplifying noise. The method constructs the pre-selection state and post-selection state of the system based on the polarization characteristics of terahertz photons. When the state of the sample to be detected changes slightly, the sample to be detected interacts weakly with the system to be measured, achieving highly sensitive detection of trace substances. The introduction of quantum weak measurement technology has significantly improved the detection sensitivity of the system to trace substances, and can detect trace substances in extremely low concentrations that are difficult to detect with traditional methods. Compared with existing terahertz detection methods, the theoretical test accuracy of this method can be improved by up to 10 orders of magnitude.

[0068] In one embodiment, before detection, the system's pre-selected state and post-selected state are close to orthogonal. On the one hand, the nearly orthogonal forward and backward state selection greatly improves the sensitivity of the system. When terahertz waves interact with trace substances, slight changes in the physical properties of the sample can cause significant changes in the key parameters of terahertz photons, thereby amplifying weak signals, suppressing background noise, improving the signal-to-noise ratio, and accurately detecting trace substances. On the other hand, it helps to accurately measure the physical parameters of the sample. Under the transmission model, the nearly orthogonal forward and backward state selection can accurately calculate the sample's refractive index, optical rotation, etc., clearly reflect the changes in the sample's physical properties, and provide key data for research and application.

[0069] In one embodiment, calculating and analyzing the physical properties of the sample to be tested loaded on the sample carrier specifically includes:

[0070] Calculate the change in output terahertz wave intensity caused by changes in the physical properties of the sample to be tested;

[0071] The change in the intensity of the output terahertz wave reflects the physical quantity of the sample to be tested;

[0072] The intensity variation of the output terahertz wave is attributed to a physical quantity of the sample to be measured, and the physical quantity includes one of the refractive index, the optical rotation, or the combined effect of the refractive index and the optical rotation.

[0073] In one embodiment, the target physical quantity of the sample to be measured is the refractive index, and the interaction mode between the terahertz wave and the sample to be measured is a transmission transmission mode or a reflection transmission mode.

[0074] Furthermore, the terahertz quantum weak measurement transmission model is:

[0075]

[0076] Wherein, α in formula (1) is the polarization state of the incident terahertz wave, |H> and |V> represent the horizontal and vertical polarization states respectively; formula (2) represents the system pre-selected state when the sample state does not change. When it is in the transmission mode, |Ap ,s | and Represent the amplitude and phase of the transfer function respectively. When it is the reflection transmission mode, |A p,s | and represent the generalized Fresnel reflection coefficient and phase angle respectively; Formula (3) represents the intermediate state of the system when the sample refractive index changes, where ΔA=Δ|A p | / |A p |-Δ|A s | / ||A s |; Formula (4) represents the post-selection state of the system, β is the post-selection angle; Formula (5) represents the system output signal strength; Formula (6) represents the initial state signal strength when the sample state does not change; Formula (7) represents the system weak value; Formula (8) represents the signal intensity contrast when the sample refractive index changes, that is, the ratio of the signal intensity change caused by the change in the sample refractive index to the initial state signal intensity, which can be used as the accuracy indicator of the detection method. The above theoretical model needs to satisfy ΔA / 2<<1 and

[0077] In one embodiment, the target physical quantity of the sample to be measured is optical rotation, and the interaction mode between the terahertz wave and the sample to be measured is a transmission mode.

[0078] Furthermore, the terahertz quantum weak measurement transmission model is:

[0079]

[0080]

[0081] The test of the optical rotation properties of the sample can only be performed in the transmission mode. Wherein, formula (9) represents the system pre-selection state, |+>=(|H>+i|V>) / 2 and |->=(|H>-i|V>) / 2 represent left-handed circularly polarized light and right-handed circularly polarized light, |H> and |V> represent horizontal and vertical polarization states respectively; formula (10) represents the intermediate state after weak coupling; formula (11) represents the system post-selection state, β is the post-selection angle; formula (12) represents the system output signal intensity; formula (13) represents the output signal intensity when the sample state does not change; formula (14) represents the system weak value; formula (15) represents the signal intensity contrast when the sample optical rotation changes, that is, the ratio of the signal intensity change caused by the change in the sample optical rotation to the initial state signal intensity, which can be used as the accuracy indicator of the detection method. The above theoretical model needs to meet

[0082] In one embodiment, the target physical quantity of the sample to be tested is the combined effect of the refractive index and the optical rotation, and the interaction mode between the terahertz wave and the sample to be tested is a transmission transmission mode. When the concentration or mass fraction of the optically active sample changes, the refractive index and the optical rotation change at the same time.

[0083] Furthermore, the terahertz quantum weak measurement transmission model is:

[0084]

[0085]

[0086] Since the test of the sample's optical rotation properties can only be performed in the transmission mode, the comprehensive effect of the sample's refractive index and optical rotation is also tested in the transmission mode. Wherein, formula (16) represents the system's pre-selected state, |H> and |V> represent the horizontal and vertical polarization states, respectively; formula (17) represents the intermediate state after weak coupling; formula (18) represents the system's post-selected state, β is the post-selected angle; formula (19) represents the system output signal intensity; formula (20) represents the system output when the sample state does not change; formula (21) represents the system's weak value; formula (22) represents the signal intensity contrast when the sample's refractive index and optical rotation change, that is, the ratio of the signal intensity change caused by the change in the sample's refractive index and optical rotation to the initial state signal intensity, which can be used as an accuracy indicator for the detection method. The above theoretical model must satisfy ΔA / 2<<1 and

[0087] In one embodiment, see Figure 1-2 A system for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology, using the above-mentioned method for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology, the system comprises:

[0088] A terahertz transmitting end 10, which outputs terahertz waves (ie, terahertz electromagnetic radiation);

[0089] A first polarizer 20, which is disposed between the terahertz emission end and the sample carrier, pre-selects the polarization state of the terahertz photons to construct a pre-selected state of the system;

[0090] A sample carrier 30, which is disposed between the first polarizer and the second polarizer, and the sample to be tested loaded on the sample carrier has a weak interaction with the terahertz photons;

[0091] A second polarizer 40 is disposed between the sample carrier and the terahertz detection end to screen the terahertz photons after interacting with the sample to be measured, and construct a post-selection state of the system;

[0092] A terahertz detection end 50 receives the output signal after pre-selection, weak coupling and post-selection;

[0093] The terahertz quantum weak measurement calculation and analysis unit calculates the terahertz wave intensity change and the target physical quantity of the sample to be measured based on the terahertz quantum weak measurement transmission model and the post-selection output signal.

[0094] According to the relative position relationship between the terahertz transmitting end, the receiving end and the sample carrier, the sample can be detected in the transmission mode or the reflection transmission mode. In the reflection transmission mode, the refractive index parameters of the sample can be detected and characterized. In the transmission transmission mode, the refractive index parameters, optical rotation parameters or the combined effect of the refractive index and optical rotation parameters of the sample can be detected and characterized.

[0095] Furthermore, the interaction mode between the terahertz wave and the sample to be tested is a transmission transmission mode or a reflection transmission mode. In the reflection transmission mode, the refractive index parameters of the sample to be tested can be detected and characterized. In the transmission transmission mode, the refractive index, optical rotation, or the combined effect of the refractive index and optical rotation of the sample to be tested can be detected and characterized.

[0096] The use of metamaterials can improve the sensitivity of terahertz detection. Metamaterials use subwavelength periodic structures to generate local electric fields, thereby enhancing the interaction between electromagnetic waves and samples. The electromagnetic properties of metamaterials depend on the shape, size and direction of their periodic structures. However, this method has significant drawbacks. It not only requires sophisticated processing equipment and technology, but also its micro-nano processing methods and technologies are highly dependent on samples. For different test samples, the lack of universality in the processing methods of metamaterials undoubtedly increases the detection cost and technical difficulty, which is not conducive to the promotion and application of terahertz detection technology in a wider range of fields.

[0097] The system for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology in this embodiment, with the help of terahertz quantum weak measurement technology, effectively amplifies the signal without amplifying technical noise. By designing the front and back selection states, it is extremely sensitive to the slight changes in the state of the sample, and can accurately detect trace substances. Compared with the traditional terahertz detection method, the theoretical test accuracy can be improved by up to 10 orders of magnitude. The system also establishes a terahertz quantum weak measurement transmission model and clarifies its weak value amplification mechanism, providing core support for the construction and application of the system, which not only improves the theoretical system of the technology, but also provides a theoretical basis for the optimization and expansion of system performance. According to the relative position relationship between the terahertz transmitter, the receiver and the sample carrier, the system can flexibly select the transmission mode or reflection transmission mode to detect the sample. The diversified measurement modes enhance the adaptability of the system to different detection scenarios and sample types, and can accurately characterize the physical parameters of the sample refractive index and optical rotation. Different from the detection methods that rely on metamaterials, this system does not rely on complex and non-versatile micro-nano processing technology, and does not require specific metamaterial processing for different samples, which effectively reduces the detection cost and technical difficulty, and is conducive to its promotion and application in a wider range of fields.

[0098] In one embodiment, an application of the above system in the detection of trace biochemical samples is also disclosed, which solves the defect of insufficient sensitivity of the current terahertz technology for the detection of trace substances.

[0099] In a more specific embodiment, please refer to the attached specification Figure 1 In the transmission mode shown, a system for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology is provided, and the system comprises: a terahertz transmitting end, a first polarizer, a sample carrier, a second polarizer, and a terahertz detecting end. The system mainly comprises the following steps:

[0100] Step 1: The terahertz wave is output from the terahertz transmitter;

[0101] Step 2: Select the polarization state of the terahertz photon by the first polarizer: α is the polarization state parameter, |H> and |V> represent the horizontal and vertical polarization states, respectively;

[0102] Step 3: The terahertz wave interacts with the sample to be tested in a transmission mode. When the sample refractive index of the sample loaded by the sample carrier does not change, the system state is: |A p,s | and represent the amplitude and phase of the transfer function respectively;

[0103] Step 4: The system state when the sample refractive index changes slightly is:

[0104]

[0105] in ΔA=Δ|A p | / |A p |-Δ|A s | / |A s |;

[0106] Step 5: Post-selection, screening the polarization state of the terahertz photon through the second polarizer as the post-selected state of this quantum system: β is the post-selection angle;

[0107] Step 6: The post-selection output signal intensity of this quantum weak measurement system is: where ΔA / 2<<1 and

[0108] Step 7: When the sample refractive index does not change, the initial signal intensity of the system output is:

[0109]

[0110] Step 8: The weak value A of this terahertz quantum weak measurement system w And the signal intensity contrast η (the ratio of the signal intensity change caused by the change in the sample refractive index to the initial signal intensity) are:

[0111] Step 9: If the sample refractive index increases from 1 to 1.001, the instructions are attached. Figure 3-4 They respectively represent the detection results of an existing terahertz detection method and a high-sensitivity detection method for trace substances based on terahertz quantum weak measurement technology. The detection performance is characterized by the intensity contrast ratio (ICR) parameter. The detection accuracy of a high-sensitivity detection method for trace substances based on terahertz quantum weak measurement technology is improved by one order of magnitude compared with the existing terahertz detection method.

[0112] In a more specific embodiment, please refer to the attached specification Figure 2 In the reflection transmission mode shown, a system for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology includes: a terahertz transmitting end, a first polarizer, a sample carrier, a second polarizer, and a terahertz detection end. The system mainly includes the following steps:

[0113] Step 1: The terahertz wave is output from the terahertz transmitter;

[0114] Step 2: Select the polarization state of the terahertz photon by the first polarizer: α is the polarization state parameter, |H> and |V> represent the horizontal and vertical polarization states, respectively;

[0115] Step 3: The terahertz wave interacts with the sample to be tested in a reflection transmission mode. When the sample refractive index of the sample loaded by the sample carrier does not change, the system state is: |A p,s | and represent the generalized Fresnel reflection coefficient and phase angle respectively;

[0116] Step 4: The system state when the sample refractive index changes slightly is:

[0117]

[0118] in ΔA=Δ|A p | / |A p |-Δ|A s | / |A s |;

[0119] Step 5: Post-selection, screening the polarization state of the terahertz photon through the second polarizer as the post-selected state of this quantum system: β is the post-selection angle;

[0120] Step 6: The post-selection output signal intensity of this quantum weak measurement system is: where ΔA / 2<<1 and

[0121] Step 7: When the sample refractive index does not change, the initial signal intensity of the system output is:

[0122]

[0123] Step 8: The weak value A of this terahertz quantum weak measurement system w And the signal intensity contrast η (the ratio of the signal intensity change caused by the change in the sample refractive index to the initial signal intensity) are:

[0124] Step 9: If the sample refractive index increases from 517.34+561.13i to 517.341+561.13i, the instruction manual Figure 5-6 They respectively represent the detection results of an existing terahertz detection method and a high-sensitivity detection method for trace substances based on terahertz quantum weak measurement technology. The detection performance is characterized by the intensity contrast ratio (ICR) parameter. The detection accuracy of a high-sensitivity detection method for trace substances based on terahertz quantum weak measurement technology is 10 orders of magnitude higher than that of the existing terahertz detection method.

[0125] In a more specific embodiment, please refer to the attached specification Figure 1 In the transmission mode shown, a system for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology includes: a terahertz transmitter, a first polarizer, a sample carrier, a second polarizer, and a terahertz detector. The system mainly includes the following steps:

[0126] Step 1: The terahertz wave is output from the terahertz transmitter;

[0127] Step 2: Select the polarization state of the terahertz photon by the first polarizer: Where |+>=(|H>+i|V>) / 2 and |->=(|H>-i|V>) / 2 represent left-handed circularly polarized light and right-handed circularly polarized light, respectively, and |H> and |V> represent horizontal and vertical polarization states, respectively;

[0128] Step 3: The terahertz wave interacts with the sample to be tested in the transmission mode. When the sample rotation of the sample loaded in the sample carrier changes slightly, the system state is: Represents the change in the sample's optical rotation angle;

[0129] Step 4: Post-selection, screening the polarization state of the terahertz photon through the second polarizer as the post-selected state of this quantum system: β is the post-selection angle;

[0130] Step 5: The post-selection output signal intensity of this quantum weak measurement system is: in

[0131] Step 6: When the optical rotation of the sample does not change, the initial signal intensity of the system output is:

[0132] Step 7: The weak value A of this terahertz quantum weak measurement system w And the signal intensity contrast η (the ratio of the signal intensity change caused by the change in sample optical rotation to the initial signal intensity) are:

[0133] Step 8: If the sample rotation angle increases from 0° to 0.01°, the instruction manual Figure 7-8They respectively represent the detection results based on an existing terahertz detection method and a highly sensitive detection method for trace substances based on terahertz quantum weak measurement technology. The detection performance is characterized by the intensity contrast (ICR) parameter. The existing terahertz detection method has no response to changes in the optical rotation of the sample. A highly sensitive detection method for trace substances based on terahertz quantum weak measurement technology has a high detection accuracy for changes in the optical rotation of the sample, and the signal intensity contrast is as high as 0.21.

[0134] In a more specific embodiment, please refer to the attached specification Figure 1 In the transmission mode shown, a system for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology includes: a terahertz transmitter, a first polarizer, a sample carrier, a second polarizer, and a terahertz detector. The system mainly includes the following steps:

[0135] Step 1: The terahertz wave is output from the terahertz transmitter;

[0136] Step 2: Select the polarization state of the terahertz photon by the first polarizer: α is the polarization state parameter, |H> and |V> represent the horizontal and vertical polarization states, respectively;

[0137] Step 3: The terahertz wave interacts with the sample to be tested in the transmission mode. When the concentration or mass fraction of the optically active sample changes, the refractive index and optical rotation change at the same time. At this time, the system state is: | ΔA and Represents the amplitude and phase changes of the system state;

[0138] Step 4: Post-selection, screening the polarization state of the terahertz photon through the second polarizer as the post-selected state of this quantum system: β is the post-selection angle;

[0139] Step 5: The post-selection output signal intensity of this quantum weak measurement system is: where ΔA / 2<<1 and

[0140] Step 6: When the sample state does not change, the system output initial signal strength is:

[0141] Step 7: The weak value A of this terahertz quantum weak measurement system w The signal intensity contrast η (the ratio of the signal intensity change caused by the change of the sample refractive index and optical rotation to the initial signal intensity) are:

[0142] Step 8: If the sample refractive index increases from 1.0 to 1.001 and the optical rotation angle increases from 0° to 0.01°, the instruction manual Figure 9-10 They respectively represent the detection results of an existing terahertz detection method and a high-sensitivity detection method for trace substances based on terahertz quantum weak measurement technology. The detection performance is characterized by the intensity contrast ratio (ICR) parameter. The detection accuracy of a high-sensitivity detection method for trace substances based on terahertz quantum weak measurement technology is 6 orders of magnitude higher than that of the existing terahertz detection method.

[0143] The present invention discloses a method, system and application for detecting trace substances based on terahertz quantum weak measurement technology. The pre-selected state and post-selected state of the quantum system are constructed based on the polarization of terahertz photons. When the physical parameters such as concentration and mass fraction of the sample state change slightly, the measuring instrument and the measured subsystem are weakly coupled, and the quantum weak value amplification effect is achieved under the weak measurement conditions. Regardless of whether the interaction mode between the terahertz electromagnetic radiation and the sample is a transmission or reflection transmission mode, the terahertz quantum weak measurement method can achieve high-precision detection of slight changes in the refractive index parameters of the detected sample. When the interaction form between the terahertz electromagnetic radiation and the sample is a transmission transmission mode, the terahertz quantum weak measurement method can achieve high-precision detection of slight changes in the sample's optical rotation or slight changes in the sample's refractive index and optical rotation at the same time, breaking through the detection limit of existing terahertz detection methods, and can be used for trace detection of biochemical samples.

[0144] In the description of this specification, if the terms "embodiment one", "this embodiment", "in an embodiment" and the like appear, it means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in the invention or at least one embodiment or example of the invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example; moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in an appropriate manner.

[0145] In the description of this specification, the terms "connect", "install", "fix", "set", "have", etc. are all understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0146] In the description of this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0147] The above description of the embodiments is to facilitate ordinary technicians in the technical field to understand and apply the technology of this case. People familiar with the technology in this field can obviously easily make various modifications to these examples and apply the general principles described here to other embodiments without creative work. Therefore, this case is not limited to the above embodiments. Modifications to the following situations should all be within the scope of protection of this case: ① A new technical solution implemented based on the technical solution of the present invention and combined with existing common knowledge, the technical effect produced by the new technical solution does not exceed the technical effect of the present invention; ② The equivalent replacement of some features of the technical solution of the present invention by using known technology, the technical effect produced is the same as the technical effect of the present invention; ③ The technical solution of the present invention can be expanded, and the substantive content of the expanded technical solution does not exceed the technical solution of the present invention; ④ The equivalent transformation made by using the contents of the description and drawings of the present invention is directly or indirectly applied to other related technical fields.

Claims

1. A method for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology, characterized in that: The invention is applied to a system for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology, the system comprising: a terahertz transmitting end, a first polarizer, a sample carrier, a second polarizer, a terahertz detection end, and a terahertz quantum weak measurement calculation and analysis unit, the method comprising: Transmitting, the terahertz transmitting end outputs a terahertz wave, and the terahertz wave passes through the first polarizer, the sample carrier, the second polarizer, and the terahertz detection end in sequence; Pre-selection, screening the polarization state α of the terahertz photon through the first polarizer as the pre-selected state of the system; Post-selection: screening the polarization state β of the terahertz photon through the second polarizer as the post-selected state of the system; Weak coupling, placing the sample carrier loaded with the sample to be tested between the first polarizer and the second polarizer, after the terahertz wave interacts with the sample to be tested, the output signal of the terahertz photons selected by the second polarizer is received and tested by the terahertz detection end; Calculate and construct a terahertz quantum weak measurement transmission model, and calculate and analyze the physical properties of the sample to be tested loaded on the sample carrier according to the output signal after the post-selection.

2. The method according to claim 1, characterized in that Before detection, the pre-selected state and post-selected state of the system are close to orthogonal.

3. The method according to claim 2, characterized in that The calculation and analysis of the physical properties of the sample to be tested loaded on the sample carrier specifically includes: Calculating the change in output terahertz wave intensity caused by the change in the physical properties of the sample to be tested; The output terahertz wave intensity variation reflects the physical quantity of the sample to be tested; The output terahertz wave intensity variation is attributed to a physical quantity of the sample to be measured, and the physical quantity includes one of a refractive index, an optical rotation, or a combined effect of the refractive index and the optical rotation.

4. The method according to claim 3, characterized in that The target physical quantity of the sample to be measured is the refractive index, and the interaction mode between the terahertz wave and the sample to be measured is a transmission transmission mode or a reflection transmission mode.

5. The method according to claim 4, characterized in that The terahertz quantum weak measurement transmission model is: Wherein, α in formula (1) is the polarization state of the incident terahertz wave, |H> and |V> represent the horizontal and vertical polarization states respectively; formula (2) represents the system pre-selected state when the sample state does not change. When it is in the transmission mode, |A p,s | and Represent the amplitude and phase of the transfer function respectively. When it is the reflection transmission mode, |A p,s | and represent the generalized Fresnel reflection coefficient and phase angle respectively; Formula (3) represents the intermediate state of the system when the sample refractive index changes, where ΔA=Δ|A p | / |A p |-Δ|A s | / |A s |; Formula (4) represents the post-selection state of the system, β is the post-selection angle; Formula (5) represents the system output signal strength; Formula (6) represents the initial state signal strength when the sample state does not change; Formula (7) represents the system weak value; Formula (8) represents the signal intensity contrast when the sample refractive index changes, that is, the ratio of the signal intensity change caused by the change in the sample refractive index to the initial state signal intensity, which can be used as the accuracy indicator of the detection method. The above theoretical model needs to satisfy ΔA / 2<<1 and 6. The method according to claim 3, characterized in that The target physical quantity of the sample to be measured is optical rotation, and the interaction mode between the terahertz wave and the sample to be measured is a transmission mode.

7. The method according to claim 6, characterized in that The terahertz quantum weak measurement transmission model is: Wherein, formula (9) represents the pre-selected state of the system, |+>=(|H>+i|V>) / 2 and |->=(|H>-i|V>) / 2 represent left-handed circularly polarized light and right-handed circularly polarized light, |H> and |V> represent horizontal and vertical polarization states, respectively; formula (10) represents the intermediate state after weak coupling; formula (11) represents the post-selected state of the system, β is the post-selected angle; formula (12) represents the output signal intensity of the system; formula (13) represents the output signal intensity when the sample state does not change; formula (14) represents the weak value of the system; formula (15) represents the signal intensity contrast when the sample optical rotation changes, that is, the ratio of the signal intensity change caused by the change in the sample optical rotation to the initial state signal intensity, which can be used as an accuracy indicator of the detection method. The above theoretical model needs to satisfy 8. The method according to claim 3, characterized in that The target physical quantity of the sample to be measured is the comprehensive effect of the refractive index and the optical rotation, and the interaction mode between the terahertz wave and the sample to be measured is a transmission mode.

9. The method according to claim 8, characterized in that The terahertz quantum weak measurement transmission model is: Wherein, formula (16) represents the pre-selected state of the system, |H> and |V> represent the horizontal and vertical polarization states respectively; formula (17) represents the intermediate state after weak coupling; formula (18) represents the post-selected state of the system, β is the post-selected angle; formula (19) represents the output signal intensity of the system; formula (20) represents the system output when the sample state does not change; formula (21) represents the weak value of the system; formula (22) represents the signal intensity contrast when the refractive index and optical rotation of the sample change, that is, the ratio of the signal intensity change caused by the change of the refractive index and optical rotation of the sample to the initial state signal intensity, which can be used as the accuracy index of the detection method. The above theoretical model needs to satisfy ΔA / 2<<1 and 10. A system for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology, characterized in that: A method for highly sensitive detection of trace substances based on terahertz quantum weak measurement technology according to any one of claims 1 to 9, wherein the system comprises: A terahertz transmitter, which outputs terahertz waves; A first polarizer, which is arranged between the terahertz emission end and the sample carrier, pre-selects the polarization state of the terahertz photons to construct a pre-selected state of the system; A sample carrier, which is arranged between the first polarizer and the second polarizer, and the sample to be tested loaded on the sample carrier has a weak interaction with the terahertz photons; A second polarizer is disposed between the sample carrier and the terahertz detection end to screen the terahertz photons after interacting with the sample to be measured, so as to construct a post-selection state of the system; A terahertz detection end receives the output signal after pre-selection, weak coupling and post-selection; The terahertz quantum weak measurement calculation and analysis unit calculates the terahertz wave intensity change and the target physical quantity of the sample to be measured based on the terahertz quantum weak measurement transmission model and the post-selection output signal.

11. The system according to claim 10, characterized in that The interaction mode between the terahertz wave and the sample to be tested is a transmission transmission mode or a reflection transmission mode. In the reflection transmission mode, the refractive index parameters of the sample to be tested can be detected and characterized. In the transmission transmission mode, the refractive index, optical rotation, or the combined effect of the refractive index and optical rotation of the sample to be tested can be detected and characterized.

12. Use of the system according to any one of claims 10-11 in the detection of trace biochemical samples.

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