Broadband measurement system and method based on Rydberg atoms
By using a broadband measurement system and method based on Rydberg atoms, and by utilizing the scanning local oscillator signal frequency and microstrip line structure, electromagnetic spectrum monitoring across multiple frequency bands was achieved, solving the problem of insufficient spectrum monitoring bandwidth in existing technologies and realizing high-sensitivity electromagnetic spectrum monitoring.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING AEROSPACE INST FOR METROLOGY & MEASUREMENT TECH
- Filing Date
- 2025-11-20
- Publication Date
- 2026-05-05
AI Technical Summary
In existing technologies, spectrum monitoring based on Rydberg atoms has a narrow instantaneous bandwidth, making it difficult to achieve wideband electromagnetic spectrum monitoring across multiple frequency bands.
A broadband measurement system and method based on Rydberg atoms is adopted, which utilizes a coupled optical laser, a probe optical laser, a photodetector, a local oscillator signal source, an atomic probe, and a spectrum analyzer. By scanning the local oscillator signal frequency and acquiring the intermediate frequency spectrum, and combining the microstrip line structure to generate a local electric field on the surface of the atomic gas cell, electromagnetic spectrum monitoring across multiple frequency bands is realized.
It achieves wideband electromagnetic spectrum monitoring across the range of 0.2 GHz to 40 GHz, with a scan time on the order of 10 seconds per GHz and a measurement sensitivity of -100 dBm/Hz. It can perform downconversion of high-frequency microwave signals at non-resonance points and is suitable for electric field strength measurement and communication reception.
Smart Images
Figure CN121978399A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a broadband measurement system and method based on Rydberg atoms, belonging to the field of spectrum measurement technology. Background Technology
[0002] Electric field measurement based on Rydberg atoms has become a cutting-edge research area in quantum precision measurement in recent years. Due to the high polarizability and sensitivity of Rydberg atoms to applied electric fields, they have been extensively studied in applications such as electric field strength measurement and communication reception. Particularly in the field of spectrum monitoring, traditional radio receivers based on metal antennas are structurally limited and cannot simultaneously measure signals across multiple frequency bands. However, Rydberg atoms, with their abundant energy level structure, can receive microwave electric fields spanning multiple frequency bands.
[0003] However, the current problem is that the instantaneous bandwidth of Rydberg atom reception is relatively narrow, and breakthroughs are urgently needed in Rydberg atom-based spectrum monitoring. Summary of the Invention
[0004] In view of this, the present invention provides a broadband measurement system and method based on Rydberg atoms, which can realize electromagnetic spectrum monitoring across multiple frequency bands.
[0005] To achieve the objectives of this invention, the following technical solutions are provided.
[0006] A broadband measurement system based on Rydberg atoms includes: a coupling laser, a probe laser, a photodetector, a local oscillator signal source, an atomic probe, and a spectrum analyzer. The atomic probe integrates an atomic gas cell and a microstrip line structure. The atomic gas cell is filled with atomic vapor, and the microstrip line structure transmits microwaves and generates a localized electric field on its surface. The coupling laser generates coupling light, and the probe laser generates probe light. The coupling light and probe light coincide within the atomic gas cell to excite atoms to the Rydberg state. The local oscillator signal source generates a local oscillator field, which acts on the atoms in the atomic gas cell through the microstrip line structure. The photodetector detects the probe light signal after it passes through the atomic gas cell and converts it into an electrical signal, which is then sent to the spectrum analyzer. The spectrum analyzer measures the spectrum of the electrical signal. A broadband electromagnetic spectrum is obtained by scanning the frequency of the local oscillator signal and acquiring the corresponding intermediate frequency (IF) spectrum. The frequency of the local oscillator signal source is adjustable, and during the local oscillator frequency scanning process, the IF signal acquired by the spectrum analyzer ranges from 50 kHz to 150 kHz.
[0007] The system is configured to optimize the intensity of the local oscillator field before measurement. Specifically, the local oscillator field and the signal field are simultaneously output to the microstrip line structure, the frequency difference between the two is kept at a fixed intermediate frequency, the intensity of the local oscillator field is adjusted to maximize the intensity of the intermediate frequency signal, and the correspondence between the local oscillator frequency and the optimal local oscillator field intensity is saved.
[0008] The microstrip line structure is a microstrip line integrated on the atomic probe, used to generate a local microwave electric field on the surface of the atomic gas cell to enhance the electric field strength and form a compact structure with the atomic probe.
[0009] This invention also provides a broadband measurement method based on Rydberg atoms. Using the system described in this invention, the method includes the following steps: Step 1: Locking the probe light to the resonance frequency of the atomic ground state and excited state, and locking the coupling light to the electromagnetic induction transparent peak, thereby exciting the atom to the Rydberg state; Step 2: Optimizing the local oscillator field intensity, specifically: simultaneously outputting the local oscillator field and signal field to a microstrip line structure, maintaining the frequency difference between the two at a fixed intermediate frequency, adjusting the intensity of the local oscillator field to maximize the intermediate frequency signal intensity, and optimizing the magnitude of the local oscillator field point by point within the measurement band, preserving the correspondence between the local oscillator frequency and the optimal local oscillator field intensity; Step 3: During measurement, fixing a local oscillator frequency and acquiring the intermediate frequency spectrum from the spectrum analyzer; Step 4: Continuously changing the local oscillator frequency, repeating Step 3, and acquiring the intermediate frequency spectra corresponding to multiple local oscillator frequencies; Step 5: Stitching together all acquired intermediate frequency spectra to obtain a broadband electromagnetic wave spectrum.
[0010] In step four, the local oscillator frequency is changed in a frequency hopping manner to avoid low-frequency noise in the photodetector. Specifically, the frequency hopping means that the local oscillator frequency starts from the initial state and changes in a predetermined sequence. After each change, the intermediate frequency signal collected covers the spectrum portion with frequencies greater than and less than the local oscillator frequency.
[0011] The fixed intermediate frequency is 100kHz, and the acquisition range of the intermediate frequency spectrum is 50kHz to 150kHz.
[0012] The wideband electromagnetic spectrum covers a range from 0.2 GHz to 40 GHz, with a scanning time on the order of 10 seconds per GHz.
[0013] In step two, optimizing the local oscillator field strength to maximize the intermediate frequency signal strength is achieved based on the intrinsic gain coefficient of the atomic superheterodyne measurement model. The intrinsic gain coefficient is affected by the local oscillator field strength and has an optimal value.
[0014] The method is applicable to non-resonance point measurement, and uses the heterodyne method to downconvert high-frequency microwave signals to medium-frequency signals, thereby realizing electromagnetic spectrum monitoring across multiple frequency bands.
[0015] Beneficial effects (1) The system of the present invention continuously collects the spectrum of the intermediate frequency signal by scanning the frequency of the local oscillator field applied to the atomic gas cell, and finally splices it to obtain the spectrum information of the wide frequency band, thus solving the technical problems existing in the mode-locking process of optical frequency comb and realizing electromagnetic spectrum monitoring across multiple frequency bands.
[0016] (2) This invention can measure the electromagnetic spectrum using a Rydberg probe. Since the microstrip line structure can generate a strong electric field on the surface and has a small size, it can be combined with an atomic probe to form an integrated atomic probe. Thus, the measurement range of Rydberg atoms can be extended from the resonance point to the non-resonance point using the heterodyne method, with the optimal sensitivity at -100dBm / Hz.
[0017] (3) Because the Rydberg has a wide response bandwidth to electromagnetic frequencies but a small instantaneous bandwidth (on the order of MHz), the measurement of electromagnetic spectrum across multiple frequency bands is achieved by scanning the local oscillator field and stitching the spectrum together. Specifically, it can monitor the electromagnetic spectrum in the range of 0.2 GHz to 40 GHz, with a scanning time of 10 seconds per GHz.
[0018] (4) In this invention, the non-resonant heterodyne method can be used to downconvert a high-frequency microwave signal to an intermediate-frequency signal at a non-resonant point, and achieve high measurement sensitivity. Recording the spectrum of the obtained intermediate-frequency signal completes the spectrum measurement of a single frequency band. Then, the frequency of the local oscillator microwave is scanned point by point, and the spectrum of the corresponding intermediate-frequency signal is acquired at the same time to obtain the spectrum of the entire frequency band.
[0019] (5) During the use of this invention, the local oscillator signal source needs to be frequency switched to achieve the measurement of the entire spectrum. Considering that the low-frequency noise of the photodetector is usually relatively large, when the local oscillator frequency remains in the initial state (i.e., the starting point of the arrow above), the intermediate frequency signal received by the spectrum analyzer is the superposition of the spectrum part with a frequency greater than the local oscillator frequency and the spectrum part with a frequency less than the local oscillator frequency, and this cycle continues until the entire spectrum is measured.
[0020] (6) In the method of the present invention, the local oscillator field and the signal field are simultaneously output to the microstrip line structure, and the frequency difference between the two is kept at a low intermediate frequency signal. The intensity of the local oscillator field is adjusted to maximize the intensity of the intermediate frequency signal, thereby optimizing the local oscillator signal. The magnitude of the local oscillator field is optimized point by point within the measurement frequency band, and the correspondence between the local oscillator frequency and the optimal local oscillator field is preserved. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the system of the present invention.
[0022] Figure 2 This is a schematic diagram of the frequency modulation process in the system of the present invention.
[0023] Figure 3 This is a schematic diagram of the spectrum monitoring results of the system of the present invention. Detailed Implementation
[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0025] This invention provides a broadband measurement system based on Rydberg atoms, the system as follows: Figure 1 As shown, the system of this invention achieves measurement based on the non-resonant heterodyne method. At the non-resonant point, the high-frequency microwave signal is down-converted to an intermediate-frequency signal, achieving high measurement sensitivity. Recording the spectrum of the obtained intermediate-frequency signal completes the spectrum measurement of a single frequency band. Then, the frequency of the local oscillator microwave is scanned point by point, and the spectrum of the corresponding intermediate-frequency signal is acquired simultaneously, thus obtaining the spectrum of the entire frequency band. Based on the above principle, this invention includes a coupled-optical laser, a probe laser, a photodetector, a local oscillator signal source, an atomic probe, and a spectrum analyzer. The coupled-optical laser and the probe laser are used to excite atoms to the Rydberg state; the photodetector is used to convert the optical signal into an electrical signal for the spectrum analyzer to measure the spectrum; the local oscillator signal source is used to generate the local oscillator field; the atomic probe integrates an atomic gas cell and a microstrip line structure. The atomic gas cell is filled with atomic vapor, and the microstrip line structure can transmit microwaves, generating a local electric field on its surface; the spectrum analyzer is used to measure the spectrum of the received signal.
[0026] The working process of the broadband measurement system based on Rydberg atoms in this embodiment of the invention is as follows: The coupled laser, after being emitted from the coupled laser, passes through two mirrors, is reflected by a dichroic mirror, enters the atomic gas cell, and then exits the gas cell before passing through a dichroic mirror and entering a light stopper. The probe laser, after being emitted from the probe laser, enters the gas cell through a mirror and then enters a photodetector. The photodetector converts the optical signal into an electrical signal, which is then fed into a spectrum analyzer to measure the spectrum. The local oscillator field enters the atomic probe via a power divider. The local oscillator microwaves propagate along the microstrip line, and a localized microwave electric field is formed on the surface of the microstrip line, acting on the atoms in the gas cell. In the gas chamber, the probe laser and the coupling laser have the same optical path. During measurement, the probe laser will be locked at the transition energy level between the ground state and the excited state. The coupling laser is locked at the transition energy level from the excited state to the Rydberg state through the EIT effect. At this time, under the action of the two beams, the atom will be excited from the ground state to the Rydberg state.
[0027] The microwave signal output from the local oscillator acts on the atoms in the gas cell. If the frequency difference between the measured signal and the local oscillator is within the instantaneous bandwidth of the measurement system, then the Rydberg atom can be considered a spatial mixer. The frequency difference between the local oscillator and the measured signal is reflected in the optical signal entering the photodetector. In the atomic superheterodyne measurement model, the signal microwave field satisfies... The transmission spectrum can be simplified as follows: ,in, This is the difference between the signal field and the local oscillator field. This represents the phase difference between the local oscillator field and the signal field. To detect the average transmitted light intensity. This represents the total intrinsic gain coefficient of the atomic superheterodyne measurement method. This allows for the detection of unknown frequencies and intensities of the target signal, where the unknown signal... It should be noted that the probe structure used in this invention can detect not only near the resonant frequency but also near non-resonant points. Due to the total intrinsic gain coefficient of the atomic superheterodyne measurement method... Due to the influence of the local oscillator field strength, there exists an optimal local oscillator field strength such that... The maximum value is determined by the frequency of the local vibration field, which needs to be optimized based on the specific frequency.
[0028] During use, the local oscillator signal source needs to be frequency-switched to achieve measurement of the entire spectrum. Considering that the low-frequency noise of photodetectors is usually relatively large, a feasible frequency-hopping scheme is as follows: Figure 2 As shown in the diagram. When the local oscillator frequency remains in the initial state (i.e., the starting point of the arrow above), the intermediate frequency signal received by the spectrum analyzer is the superposition of the spectral components with frequencies higher than the local oscillator frequency and those lower than the local oscillator frequency, i.e., the portion corresponding to number 1. Then, the local oscillator frequency is changed according to the arrows in the diagram, allowing measurement of the spectra corresponding to numbers 2 and 3, and so on, until the entire spectrum is measured. An example of the obtained spectrum results is shown below. Figure 3 As shown.
[0029] This invention also provides a broadband measurement method based on Rydberg atoms. The specific steps of the method are as follows: 1. Lock the probe light at the resonance frequency between the ground state and the excited state, and lock the coupling light at the EIT peak. This step can excite the atom to the Rydberg state. Connect the probe light signal to the spectrum analyzer.
[0030] 2. Simultaneously output the local oscillator field and the signal field to the microstrip line structure, maintaining a low frequency difference between them at the intermediate frequency (IF) (100kHz in this embodiment). Adjust the intensity of the local oscillator field to maximize the IF signal intensity. This completes the optimization of the local oscillator signal. Optimize the magnitude of the local oscillator field point-by-point within the measurement frequency band. Save the correspondence between the local oscillator frequency and the optimal local oscillator field.
[0031] 3. During measurement, fix a local oscillator frequency and collect the spectrum from the spectrum analyzer. The spectrum range is 50kHz-150kHz.
[0032] 4. Continuously increase the local oscillator frequency to acquire the spectrum generated by the spectrum analyzer each time. The specific frequency change method is as follows: Figure 2 As indicated by the arrows above, the spectrum obtained from each acquisition is labeled with a number below. Finally, all the obtained intermediate frequency spectra are combined to obtain the entire broadband electromagnetic wave spectrum.
[0033] This invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered within the scope of protection of this invention.
Claims
1. A broadband measurement system based on Rydberg atoms, characterized in that, include: Coupled-optical lasers, probe lasers, photodetectors, local oscillator signal sources, atomic probes, and spectrum analyzers; The atomic probe integrates an atomic gas chamber and a microstrip line structure. The atomic gas chamber is filled with atomic vapor, and the microstrip line structure is used to transmit microwaves and generate a local electric field on the surface. The coupling laser is used to generate coupling light, and the probe laser is used to generate probe light. The coupling light and probe light coincide in the atomic gas chamber to excite the atoms to the Rydberg state. The local oscillator signal source is used to generate a local oscillator field and acts on the atoms in the atomic gas chamber through a microstrip line structure. The photodetector is used to detect the probe light signal after passing through the atomic gas chamber and convert it into an electrical signal to be sent to the spectrum analyzer. The spectrum analyzer is used to measure the spectrum of the electrical signal. A wideband electromagnetic spectrum is obtained by scanning the frequency of the local oscillator signal and acquiring the corresponding intermediate frequency spectrum.
2. The system according to claim 1, characterized in that, The frequency of the local oscillator signal source is adjustable, and during the local oscillator frequency scanning process, the intermediate frequency signal collected by the spectrum analyzer is in the range of 50kHz to 150kHz.
3. The system according to claim 1 or 2, characterized in that, The system is configured to optimize the intensity of the local oscillator field before measurement. Specifically, the local oscillator field and the signal field are simultaneously output to the microstrip line structure, the frequency difference between the two is kept at a fixed intermediate frequency, the intensity of the local oscillator field is adjusted to maximize the intensity of the intermediate frequency signal, and the correspondence between the local oscillator frequency and the optimal local oscillator field intensity is saved.
4. The system according to claim 1, characterized in that, The microstrip line structure is a microstrip line integrated on an atomic probe, used to generate a local microwave electric field on the surface of the atomic gas cell to enhance the electric field strength and form a compact structure with the atomic probe.
5. A broadband measurement method based on Rydberg atoms, characterized in that, Using the system as described in any one of claims 1 to 4, the method comprises the following steps: Step 1: Locking the probe light to the resonance frequency of the atomic ground state and excited state, and locking the coupling light to the electromagnetic induction transparent peak, thereby exciting the atom to the Rydberg state; Step 2: Optimizing the local oscillator field intensity, specifically: simultaneously outputting the local oscillator field and the signal field to the microstrip line structure, keeping the frequency difference between the two at a fixed intermediate frequency, adjusting the intensity of the local oscillator field to maximize the intermediate frequency signal intensity, and optimizing the magnitude of the local oscillator field point by point within the measurement frequency band, and saving the correspondence between the local oscillator frequency and the optimal local oscillator field intensity; Step 3: During measurement, fixing a local oscillator frequency and acquiring the intermediate frequency spectrum of the spectrum analyzer; Step 4: Continuously changing the local oscillator frequency, repeating Step 3, and acquiring the intermediate frequency spectrum corresponding to multiple local oscillator frequencies; Step 5: stitching together all acquired intermediate frequency spectra to obtain a wideband electromagnetic wave spectrum.
6. The method according to claim 5, characterized in that, In step four, the local oscillator frequency is changed in a frequency hopping manner to avoid low-frequency noise in the photodetector. The frequency hopping manner is as follows: the local oscillator frequency starts from the initial state and changes in a predetermined sequence. After each change, the intermediate frequency signal collected covers the spectrum portion with frequencies greater than and less than the local oscillator frequency.
7. The method according to claim 5 or 6, characterized in that, The fixed intermediate frequency is 100kHz, and the acquisition range of the intermediate frequency spectrum is 50kHz to 150kHz.
8. The method according to claim 5, characterized in that, The wideband electromagnetic spectrum covers a range from 0.2 GHz to 40 GHz, with a scan time on the order of 10 seconds per GHz.
9. The method according to claim 5, characterized in that, In step two, optimizing the local oscillator field strength to maximize the intermediate frequency signal strength is achieved based on the intrinsic gain coefficient of the atomic superheterodyne measurement model. The intrinsic gain coefficient is affected by the local oscillator field strength and has an optimal value.
10. The method according to claim 5, characterized in that, The method is applicable to non-resonance point measurements. It uses a heterodyne method to downconvert high-frequency microwave signals to intermediate-frequency signals, enabling electromagnetic spectrum monitoring across multiple frequency bands.