Quantum heterodyne detection method based on organic molecule system
Through the quantum heterodyne detection method based on organic molecular system, the weak signal is amplified by the stimulated radiation effect, which solves the noise and signal attenuation problems of traditional receivers when detecting weak signals, and achieves higher sensitivity and heterodyne detection functions.
Patent Information
- Application Number
- CN202411754204.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-02
- Publication Date
- 2025-03-11
AI Technical Summary
When detecting weak signals, traditional receivers face limitations such as thermal noise, quantum noise, environmental noise, receiver gain and bandwidth limitations, and signal attenuation, making it difficult to break through the standard quantum limits and achieve higher sensitivity.
The quantum heterodyne detection method based on the organic molecular system is adopted, through the interaction of weak signals with the spin energy level of organic molecules, the signal to be tested is amplified by the stimulated radiation effect, the signal-to-noise ratio is improved, and heterodyne detection is realized.
Break through the standard quantum limits, achieve higher detection sensitivity, and have heterodyne detection function, which can effectively amplify weak signals in low noise environments.
Smart Images
Figure CN119596284A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the fields of electron stimulated radiation, quantum amplification technology and quantum precision measurement technology, and in particular to a quantum heterodyne detection method based on an organic molecular system. Background Art
[0002] In scientific research and engineering applications, the detection of weak signals is of great significance, but traditional receivers face many limitations when detecting weak signals, such as thermal noise, quantum noise, environmental noise, receiver gain and bandwidth limitations, and signal attenuation. To overcome these challenges, scientists and engineers have proposed a series of improvements and new technologies, such as low-noise amplifiers, phase-locked loops, digital signal processing, and artificial intelligence and machine learning.
[0003] These technologies have improved the sensitivity and accuracy of signal detection to a certain extent. However, when working, traditional receivers usually choose to make multiple measurements under the same conditions and average the results. In this way, the fluctuation of the measurement results is at least proportional to a proportional factor N. -1 / 2 , where N is the number of repeated measurements. This proportionality factor defines the standard quantum limit (SQL), which has been proven to be an unbreakable limit through classical repeated measurement methods. In a quantum system with multiple independent identical particles, the external field interacts with multiple particles at the same time, and the result obtained is the average result of multiple particles, which is equivalent to taking the average of multiple measurements in the classic way.
[0004] However, unlike classical measurement, quantum systems are subject to the uncertainty principle, resulting in the Heisenberg limit, which is proportional to N. Therefore, to a certain extent, receivers based on quantum systems are expected to break through the measurement limits of traditional receivers and achieve higher sensitivity.
[0005] How to design and develop a detection method based on quantum system is an urgent problem to be solved. Summary of the invention
[0006] In view of the above technical problems, the present invention provides a quantum heterodyne detection method based on an organic molecular system.
[0007] The quantum heterodyne detection method based on the organic molecule system provided by the present invention comprises a receiving module, an organic molecule module, an excitation module and a detection module: when the receiving module receives a signal to be measured, it will pre-process the signal and then send it to the organic molecule module, and at the same time send a switch signal to the excitation module; after receiving the signal, the excitation module excites the organic molecule sample, and the sample undergoes a stimulated radiation process, amplifies the signal to be measured with ultra-low noise, and then sends it to the detection module, and according to theoretical analysis, heterodyne detection can be realized.
[0008] Preferably, the excitation device selected for the excitation module can be a laser, a high-voltage capacitor or an inductor, and has the function of identifying a switch signal. It will only start working when a signal is recognized, and will automatically stop working after a set time is reached. The excitation module should select a suitable excitation device according to the properties of the sample material used.
[0009] Preferably, the organic molecule module comprises an organic molecule sample material and a resonant cavity, wherein the sample is placed in the resonant cavity; after excitation, the molecules used generate spin energy levels with population differences, and the energy level broadening covers the signal band to be measured; the resonant frequency of the resonant cavity used should match the spin energy level frequency.
[0010] Preferably, the receiving module at least includes a microwave receiving antenna and a front-end processing device (such as a switch signal transmitter), and has the ability to send a switch signal, and can send the signal to the excitation module.
[0011] Preferably, the detection module comprises a back-end processing device for filtering, amplifying, and isolating the signals emitted by the organic molecule module after the interaction, and sending the signals to an oscilloscope, a spectrometer, and other devices.
[0012] Compared with the related art, the quantum heterodyne detection method based on organic molecular system provided by the present invention has the following beneficial effects:
[0013] In the scheme of the present invention, the weak signal interacts with the spin energy level of the organic molecule to amplify the signal to be measured, improve the signal-to-noise ratio, break through the standard quantum limit, thereby achieving higher detection sensitivity and enabling heterodyne detection. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 A schematic flow chart of a quantum heterodyne detection method based on an organic molecular system provided by the present invention;
[0015] Figure 2 This is a diagram of the electron spin energy level structure of common organic molecules in the present invention. DETAILED DESCRIPTION
[0016] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.
[0017] The present invention proposes a quantum heterodyne detection method based on an organic molecular system, such as Figure 1 As shown, it includes a receiving module, an organic molecule module, an excitation module, and a detection module.
[0018] When the signal to be detected is received by the receiving module, it will first be pre-processed, and the purest signal source will be obtained through filtering and other means, and then transmitted to the organic molecule module. At the same time, the receiving module will send a switch signal to the excitation module.
[0019] The excitation module usually uses excitation devices such as lasers, high-voltage capacitors and inductors. After receiving the start signal sent by the receiving module, the excitation module starts to work and excites the sample material in the organic molecule module to achieve the working state described later. Through reasonable circuit design, it can be ensured that the signal to be measured and the excitation signal act on the sample material at the same time.
[0020] The organic molecule module contains a resonant cavity and the sample material placed in the resonant cavity. Some common Figure 2 The organic molecules with the spin energy levels shown are representative molecules such as benzene and naphthalene. First, S0 is the singlet ground state, and all spins are in this state when not excited. After excitation, the spin will reach the first excited state S1. At this time, a part of the spin will reach the spin triplet T2 state through spontaneous intersystem crossing, and reach the T1 state through a rapid internal conversion process. In the absence of an external magnetic field or a very weak geomagnetic environment, the T1 state will split into three sub-energy levels X, Y, and Z. This state is the working state of the material. For different organic molecular materials, the energy level difference and population of the three states X, Y, and Z are different, but for a certain organic molecule, the two states with the largest population difference can always be found. Here it is assumed that there is a molecule M whose X and Z states have the largest population difference, and the frequency corresponding to the energy level difference between X and Z is f. By designing a resonant cavity with the same resonant frequency f, the interaction between the molecules in the cavity and the microwave field can be realized. The signal to be measured transmitted by the receiving module will induce the stimulated radiation effect between X and Z, amplify the signal to be measured exponentially with an extremely low noise level, and then send it to the back-end detection module.
[0021] After back-end processing, the detection module can view the ultra-low noise amplified signal to be tested on detection devices such as oscilloscopes or spectrum analyzers, thus completing a weak signal detection.
[0022] Furthermore, the detection method based on organic molecular system has heterodyne detection function.
[0023] First, the stimulated radiation process of the above organic molecules under the induction of the measured signal can be described by the following three equations (i.e., quantum Langevin equations):
[0024]
[0025]
[0026]
[0027] Here, we neglect the effect of thermal photons, because the input photons far outnumber thermal photons. And there is an implicit assumption that the frequency of all spins is the same, so the detuning frequency of all spins is Δ s In heterodyne measurement, we assume that the spin energy level difference and the resonant frequency of the resonant cavity are the same, that is, Δ s =Δ c , and define it as the local oscillator frequency in this method. ⊥ represents the longitudinal decay rate between sublevels X and Z; γ || represents the lateral attenuation rate of the system; κ c represents the photon decay rate in the cavity; η represents the input microwave intensity to be measured; g represents the spin-microwave coupling intensity; N is the layout difference between X and Z.
[0028] When the frequency of the signal to be measured is different from the spin energy level difference and the resonant frequency, we call it heterodyne detection. In order to obtain the results under heterodyne detection, we can do the following theoretical analysis. We use the classical magnetic resonance model to analyze its basic mechanism, in which the electron spin is regarded as the classical magnetic moment. This model is an approximation and simplification of the above quantum Langevin equation in heterodyne detection, which is easier to solve and analyze than the original quantum Langevin equation. In the presence of a detuned microwave field, the dynamics of the electron spin can be described by the Bloch equation in the following rotating coordinate system:
[0029]
[0030] Among them, M x 、M y 、M z are the three components of the spin magnetic moment, T1 and T2* are the spin-lattice relaxation time and decoherence time, respectively, Δω represents the detuning frequency, and ω1 is the Rabi frequency of the spin under the control of the microwave magnetic field B1. The Bloch equation describes the dynamics of the electron spin (and also characterizes the output microwave power coupled out of the resonant cavity) and is mainly related to the frequency and amplitude of the driving microwave magnetic field of the input cavity. The above equation is a system of linear constant coefficient differential equations, so its solution can be obtained by calculating the eigenvalues of its coefficient matrix:
[0031]
[0032] The solution of the Bloch equation can be written as M = C1exp(λ1t) + C2exp(λ2t) + C3exp(λ3t) + D, where λ i is the eigenvalue of the coefficient matrix, i.e., i Satisfies the duration equation:
[0033]
[0034] The three roots of the equation λ i can be written as λ1=a,λ 2,3 = b ± iΩ, where a, b and Ω are all real numbers. i The real part of (i.e., the real numbers a and b) describes the decay of the spin magnetic moment, while the imaginary part Ω represents the frequency of the oscillation. Under the secular approximation (i.e., T1, T2*>>1 / Δω, 1 / ω1), Ω can be expressed as Ω=(Δω 2 +ω1 2 ) 1 / 2 In other words, when the microwave power to be measured is very weak, the Rabi frequency ω1 brought by the microwave B1 field is very weak, which will lead to a detuning frequency Δω>>ω1, and then Ω=Δω can be approximately obtained. When the microwave frequency to be measured differs from the spin energy level frequency by Δω, a modulated signal with a frequency of Δω will be detected in the detection module, and then a heterodyne detection can be completed.
[0035] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.
Claims
1. A quantum heterodyne detection method based on an organic molecular system, characterized in that: Including receiving module, organic molecule module, excitation module and detection module: When the receiving module receives the signal to be tested, it will pre-process the signal and then send it to the organic molecule module, and at the same time send a switch signal to the excitation module; After receiving the signal, the excitation module excites the organic molecule sample. The sample undergoes a stimulated radiation process, amplifies the signal to be measured with ultra-low noise, and then sends it to the detection module. According to theoretical analysis, heterodyne detection can be achieved.
2. The quantum heterodyne detection method based on an organic molecular system according to claim 1, characterized in that: The excitation device selected by the excitation module can be a laser, a high-voltage capacitor or an inductor, and has the function of identifying a switch signal. It will start working only when a signal is identified, and will automatically stop working after the set time is reached.
3. The quantum heterodyne detection method based on an organic molecular system according to claim 1, characterized in that: The organic molecule module comprises an organic molecule sample material and a resonant cavity, wherein the sample is placed in the resonant cavity; after being excited, the organic molecule sample material generates a spin energy level with a population difference, and the energy level broadening covers the signal band to be measured; and the resonant frequency of the resonant cavity should match the spin energy level frequency.
4. The quantum heterodyne detection method based on an organic molecular system according to claim 1, characterized in that: The receiving module includes a microwave receiving antenna and a front-end processing device (such as a switch signal transmitter), and has the ability to send a switch signal, and can send the signal to the excitation module.
5. The quantum heterodyne detection method based on an organic molecular system according to claim 1, characterized in that: The detection module includes a back-end processing device for filtering, amplifying, and isolating the signals after interaction emitted by the organic molecule module, and sending the signals to an oscilloscope or a spectrometer.