Quantum current sensor microwave system and method based on single sideband signal modulation

Abstract

The invention discloses a quantum current sensor microwave system and method based on single sideband signal modulation, and belongs to the technical field of quantum measurement, and the system comprises a signal source which is used for outputting a high-frequency carrier signal and a low-frequency baseband signal; the microwave bridge is used for receiving the high-frequency carrier signal and the low-frequency baseband signal, performing single-sideband modulation on the high-frequency carrier signal and the low-frequency baseband signal to generate a single-sideband microwave signal, and switching to a modulation path or a straight-through path under the action of a control signal; and the radiation structure is used for receiving the single-sideband microwave signal and converting the single-sideband microwave signal into an alternating magnetic field acting on the quantum system. Through the single sideband signal modulation technology, carrier signals and useless sideband signals are effectively suppressed, the efficiency of signal transmitting power is improved, and therefore the sensitivity and accuracy of current measurement are remarkably improved. A vector signal generator and an arbitrary waveform generator are adopted to realize accurate modulation of a high-frequency carrier signal and a low-frequency baseband signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantum measurement, and in particular to a quantum current sensor microwave system and method based on single sideband signal modulation. BACKGROUND

[0002] In the existing quantum current sensor microwave system, in order to excite and measure the quantum state working medium (such as NV color center, superconducting quantum bit, etc.), it is usually necessary to apply a high-frequency alternating magnetic field to it through a microwave signal. The existing technology generally adopts double sideband signal modulation technology to generate a microwave signal, which realizes the modulation output of the microwave pulse by simultaneously superimposing a high-frequency carrier signal and a low-frequency baseband signal.

[0003] However, the double sideband modulation technology has the following defects:

[0004] Because the carrier signal occupies a large proportion of the power in the entire transmission process, the overall transmission power efficiency of the system is low, and the power utilization rate is insufficient;

[0005] The useless sideband signals contained in the double sideband signal cannot be completely filtered out, and these signals will interfere with the quantum state control experiment, reduce the measurement accuracy and stability of the results;

[0006] Under the double sideband modulation mode, the frequency spectrum utilization rate is low, and the system has insufficient flexibility when switching between working modes.

[0007] In view of the above problems, some researches propose to improve by increasing filtering circuits, improving device linearity, etc., but these methods increase the complexity of the system, introduce additional loss, and do not fundamentally solve the structural defects of double sideband modulation. Therefore, there is an urgent need for a technical solution that can effectively improve the transmission power efficiency, suppress useless sideband signals, simplify the system structure, and improve the measurement accuracy and stability to meet the needs of quantum current sensors for high sensitivity and high stability. SUMMARY

[0008] In view of the above problems, the present application is proposed.

[0009] Therefore, the technical problem solved by the present application is that in the existing quantum current sensor microwave system, the double sideband signal modulation technology is mostly used. The double sideband modulation technology has the following disadvantages: the carrier signal occupies a large proportion of the signal transmission power, resulting in low signal transmission power efficiency. The useless sideband signals contained in the double sideband signal will interfere with the quantum control experiment, affecting the measurement accuracy and stability.

[0010] To solve the above technical problems, the present application provides the following technical scheme: a quantum current sensor microwave method based on single sideband signal modulation, comprising,

[0011] a signal source for simultaneously outputting a high-frequency carrier signal as a modulated carrier source and a low-frequency baseband signal as a modulated signal;

[0012] a microwave bridge connected to the signal source for receiving the high-frequency carrier signal and the low-frequency baseband signal, forming a single-sideband microwave signal through modulation, and switching the transmission path of the high-frequency carrier signal to a modulation path or a straight-through path upon receiving a control signal;

[0013] a radiation structure connected to the microwave bridge for receiving the single-sideband microwave signal and emitting it as an alternating magnetic field acting on the working area of the quantum system.

[0014] As a preferred scheme of the quantum current sensor microwave system based on single-sideband signal modulation, the signal source is configured to output two mutually orthogonal low-frequency baseband signals, and the two low-frequency baseband signals are combined with the high-frequency carrier signal to form mutually orthogonal modulated signal components for generating a single-sideband microwave signal.

[0015] The preferred technical scheme has the beneficial effect that by outputting two mutually orthogonal low-frequency baseband signals, the single-sideband signal formed after mixing with the high-frequency carrier signal has a higher sideband suppression ratio, effectively reducing unwanted sideband interference, improving microwave power utilization and quantum measurement accuracy.

[0016] As a preferred scheme of the quantum current sensor microwave system based on single-sideband signal modulation, the microwave bridge selectively switches the transmission path of the high-frequency carrier signal through a control signal, switching the output mode between the modulation path and the straight-through path.

[0017] As a preferred scheme of the quantum current sensor microwave system based on single-sideband signal modulation, the radiation structure is configured to form a locally enhanced alternating magnetic field in the target area of the quantum system.

[0018] As a preferred scheme of the quantum current sensor microwave system based on single-sideband signal modulation, the radiation structure includes a main slot line disposed on an insulating substrate and an Ω-shaped open slot line coupled to the main slot line, the Ω-shaped open slot line being configured to form a locally enhanced alternating magnetic field in the central region and apply the magnetic field to the quantum state working medium located in the region.

[0019] The preferred technical scheme has the beneficial effect that by using a combination structure of a main slot line and an Ω-shaped open slot line in the radiation structure and forming a locally enhanced alternating magnetic field in the central region, the concentration and intensity of the radiated magnetic field are significantly improved, the driving efficiency of the quantum system is improved, and energy loss and radiation interference are reduced.

[0020] As a preferred scheme of the quantum current sensor microwave system based on single sideband signal modulation, the energy coupling between the main slot line and the omega open slot line is realized through a T-shaped slot, and the structure and characteristic impedance of each port of the T-shaped slot are matched.

[0021] As a preferred scheme of the quantum current sensor microwave system based on single sideband signal modulation, the insulating substrate of the radiation structure is made of a transparent material with high dielectric constant.

[0022] As a preferred scheme of the quantum current sensor microwave system based on single sideband signal modulation, the microwave bridge and the radiation structure are connected through a radio frequency coaxial cable with matched characteristic impedance, and the interface of the radio frequency coaxial cable is a standard radio frequency connector.

[0023] As a preferred scheme of the quantum current sensor microwave system based on single sideband signal modulation, a matching load with a characteristic impedance of 50 ohms is connected to the end of the system.

[0024] The application provides a quantum current sensor microwave method based on single sideband signal modulation.

[0025] To solve the above technical problems, the application provides the following technical scheme: a quantum current sensor microwave method based on single sideband signal modulation, comprising: outputting a high-frequency carrier signal and a low-frequency baseband signal through a signal source;

[0026] The high-frequency carrier signal and the low-frequency baseband signal are received by a microwave bridge, and single sideband modulation is performed on both to generate a single sideband microwave signal;

[0027] The microwave bridge is controlled to switch between a modulation path and a straight-through path to output the signal of the selected path;

[0028] The single sideband microwave signal is received by a radiation structure and converted into an alternating magnetic field applied to a quantum state working medium.

[0029] The application has the following beneficial effects: through single sideband signal modulation technology, the carrier signal and the unwanted sideband signal are effectively suppressed, the efficiency of signal transmission power is improved, and the sensitivity and accuracy of current measurement are significantly improved. The use of a vector signal generator and an arbitrary waveform generator realizes accurate modulation of the high-frequency carrier signal and the low-frequency baseband signal, ensures the stability of the frequency and phase of the microwave radio frequency pulse signal, and further improves the measurement accuracy.

[0030] The high-speed microwave switch controlled by the TTL level is used to realize flexible switching between the modulation path and the straight-through path, and the programmable dual-mode output is completed by cooperating with the power combiner, which helps to meet the microwave pulse control requirements under different excitation and measurement conditions in the quantum system.

[0031] The radiation structure is designed based on an omega open slot line, and the energy coupling between the main slot line and the omega ring is realized through a T-shaped slot structure, so that the local enhancement distribution of the radiation magnetic field is formed in the center area of the structure, the signal loss is reduced, and the energy conversion efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0033] Figure 1 A general architecture diagram of a quantum current sensor microwave system based on single sideband signal modulation is provided for an embodiment of the present application.

[0034] Figure 2 A single sideband signal modulation principle diagram of a quantum current sensor microwave system based on single sideband signal modulation is provided for an embodiment of the present application.

[0035] Figure 3 A microwave bridge structure schematic diagram of a quantum current sensor microwave system based on single sideband signal modulation is provided for an embodiment of the present application.

[0036] Figure 4 A radiation structure overall structure diagram and a radiation structure equivalent circuit diagram of a quantum current sensor microwave system based on single sideband signal modulation are provided for an embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings in the specification. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0038] Embodiment 1, refer to Figure 1 For an embodiment of the present application, the embodiment provides a quantum current sensor microwave system based on single sideband signal modulation, which comprises:

[0039] a signal source for simultaneously outputting a high-frequency carrier signal as a modulated carrier source and a low-frequency baseband signal as a modulated signal;

[0040] In a preferred embodiment of the present application, the signal source comprises a separate vector signal generator and an arbitrary waveform generator, the high-frequency carrier signal is output by the vector signal generator, the frequency range covers 1GHz to 4GHz, and can be accurately set to 2.87GHz; the low-frequency baseband signal is output by the arbitrary waveform generator, the amplitudes and frequencies of the two signals are the same, the phases are 90° apart, and the switching between pulse and continuous wave is supported.

[0041] The beneficial effects of the preferred technical solution are: the output signal frequency is accurate and the phase is stable, which can meet the resonance modulation requirements of the quantum system and ensure the low distortion and low noise performance of the signal source.

[0042] In an optional embodiment of the present application, the signal source adopts an integrated signal generation module, integrates the high-frequency carrier signal source and the low-frequency baseband signal source into one, and internally builds two independent low-frequency baseband output channels to reduce external wiring and system volume.

[0043] In another optional embodiment of the present application, the signal source adopts a distributed signal source architecture, that is, multiple modules generate high-frequency carrier and low-frequency baseband signals respectively, and the signals are transmitted synchronously through optical fiber or coaxial cable at a long distance, which is suitable for application scenarios with high requirements for electromagnetic environment or requiring long-distance isolation.

[0044] a microwave bridge connected with the signal source, for receiving the high-frequency carrier signal and the low-frequency baseband signal, forming a single sideband microwave signal through modulation, and switching the transmission path of the high-frequency carrier signal to the modulation path or the straight-through path when receiving a control signal;

[0045] a radiation structure connected with the microwave bridge, for receiving the single sideband microwave signal and emitting it as an alternating magnetic field to act on the working area of the quantum system.

[0046] In a preferred embodiment of the present application, the radiation structure comprises a main slot line and an omega open slot line arranged on a quartz glass substrate with a thickness of about 0.1mm, the main slot line and the omega open slot line are coupled through a T-shaped slot, and the three port structures of the T-shaped slot are the same and the characteristic impedance is matched. The magnetic field strength in the central region of the omega open slot line is the largest, which meets the requirements of driving NV color centers.

[0047] The beneficial effects of the preferred technical solution are: compact structure, excellent dielectric performance of materials, ability to form a locally enhanced and distributed magnetic field, small loss and high transmission efficiency.

[0048] In an optional embodiment of the present invention, the radiating structure substrate is made of a ceramic material with a high dielectric constant instead of a quartz glass substrate to improve mechanical strength and heat resistance while maintaining high-frequency characteristics.

[0049] In another optional embodiment of the present invention, the radiation structure adopts a metallized polymer film substrate with a thickness of less than 0.1 mm, which facilitates flexible installation or is used in space-constrained situations. At the same time, magnetic flux concentrating material is added to the outer periphery of the Ω-shaped groove to further improve the central magnetic field strength.

[0050] Existing quantum current sensor microwave systems employ double-sideband modulation, which results in significant carrier power consumption during signal transmission and the inability to completely suppress unwanted sideband signals, interfering with the response of the quantum state working medium and leading to unstable measurement results. This embodiment introduces single-sideband modulation technology into the microwave bridge, using a hybrid modulation of the high-frequency carrier signal output from the signal source with two mutually orthogonal low-frequency baseband signals. This effectively suppresses unwanted sideband signals, reduces interference, and improves the efficiency of transmission power utilization and the system's measurement stability.

[0051] The entire system consists of a signal source, a microwave bridge, and a radiating structure. The signal source provides the high-frequency carrier signal and low-frequency baseband signal required for modulation. The microwave bridge performs single-sideband modulation on both signals and outputs a microwave signal. The output path can be flexibly switched via a TTL control signal, supporting both pass-through and modulation modes. The radiating structure converts the single-sideband signal output by the microwave bridge into an alternating magnetic field acting on the quantum state working medium within the target region. Through this structural configuration, the system can effectively solve the problems of low power utilization and severe interference in traditional double-sideband systems without increasing additional complexity.

[0052] In practical implementation, a vector signal generator is selected as the signal source, with an output frequency range covering 1GHz to 4GHz for high-frequency carrier signals, and set to 2.87GHz to meet the resonant modulation requirements of the quantum state working medium. The low-frequency baseband signal is output by an arbitrary waveform generator, and the two signals are orthogonal to each other for mixing modulation. The microwave bridge selects the modulation path or the direct path through a high-speed microwave switch, performs I / Q modulation on the high-frequency carrier signal and the low-frequency baseband signal in the mixer, and forms a single-sideband signal output through a power combiner. The radiating structure consists of a main slot line and an Ω-shaped open-circuit slot line set on a high-dielectric-constant transparent substrate. The energy coupling between the two is achieved through a T-shaped slot, forming a locally enhanced alternating magnetic field in the Ω-shaped open region. This region is used to place the quantum state working medium for experimental measurements.

[0053] Example 2, refer to Figures 1-4 As one embodiment of the present invention, based on the previous embodiment, a microwave system for a quantum current sensor based on single-sideband signal modulation is provided, comprising:

[0054] The signal source is used to generate high-frequency carrier signals and low-frequency baseband signals; the microwave bridge uses single-sideband modulation technology to mix and modulate the high-frequency carrier signal and the low-frequency baseband signal, and outputs a specific sequence of microwave radio frequency pulse signals through a switch controlled by TTL level; after power amplification, the signal is converted from a radiating structure into an alternating magnetic field applied to the quantum system of the quantum current sensor, and a 50Ω load is connected at the end of the circuit for impedance matching.

[0055] Specifically, the signal source in this embodiment consists of a high-frequency carrier signal source and a low-frequency baseband signal source. The high-frequency carrier signal source employs a vector signal generator, capable of outputting a stable high-frequency signal covering a frequency range of 1 GHz to 4 GHz, and can be precisely set to 2.87 GHz to match the resonant frequency of the quantum state working medium. The low-frequency baseband signal source employs an arbitrary waveform generator, outputting a moduloable low-frequency signal with dual-channel independent control capability, capable of generating two orthogonal signals with the same amplitude and frequency but a 90° phase difference. This arbitrary waveform generator supports free switching between continuous waveforms and pulse waveforms to adapt to modulation requirements under different experimental conditions.

[0056] In this embodiment, the microwave bridge inputs the high-frequency carrier signal and the low-frequency orthogonal baseband signal from the signal source to the mixer, respectively. A single-sideband signal is formed through I / Q modulation, and a high-speed switch controlled by a TTL signal is used to flexibly switch between the modulation path and the direct path. The output microwave signal, after power amplification, is emitted through a radiation structure coupled to the main slot line via an Ω-shaped open slot line, forming a locally enhanced alternating magnetic field within the target region of the quantum system to drive the quantum state working medium. The output of the entire circuit is matched with a 50Ω load to ensure stable transmission of the radio frequency signal and prevent reflection.

[0057] Example 3, an embodiment of the present invention, provides a microwave system for a quantum current sensor based on single-sideband signal modulation, based on the previous embodiment, comprising:

[0058] The microwave bridge mainly consists of a vector signal source, an arbitrary waveform generator, microwave switching devices, a 1-to-2 90° phase difference power divider, multiple frequency synthesizers, and multiple 0° phase difference power synthesizers.

[0059] In this embodiment, a vector signal generator is used to generate a high-frequency local oscillator signal, serving as the carrier source for microwave modulation. An arbitrary waveform generator outputs two orthogonal low-frequency baseband signals with the same frequency and amplitude but a 90° phase difference, serving as modulation signals. The high-frequency carrier signal first passes through a TTL-controlled high-speed microwave switching device to achieve time-division control of the signal path. When the TTL signal is high, the high-frequency carrier signal does not participate in modulation and is directly output through a 0° phase difference power combiner channel, serving as a reference signal or a direct path. When the TTL signal is low, the high-frequency carrier signal is guided to a 1-to-2 90° phase difference power divider, which divides the carrier signal into two equal amplitudes and applies a 90° phase difference, forming two mutually orthogonal high-frequency signals.

[0060] Simultaneously, the two outputs of the arbitrary waveform generator are respectively fed into two independent mixers for I / Q mixing with the two aforementioned high-frequency carrier signals to obtain two mixed output signals. Subsequently, these two mixed signals are fed into a 0° phase difference power combiner, where they are combined in phase to obtain a single-sideband microwave signal, effectively filtering out carrier and non-target sideband components. Finally, this single-sideband signal is fed into the final stage power combiner, where it is combined with a high-frequency direct-through carrier signal output from the TTL control channel to achieve programmable dual-mode output. The combined signal is further amplified by a power amplifier before being sent to subsequent modules of the system.

[0061] Example 4, refer to Figure 4 As one embodiment of the present invention, based on the previous embodiment, a microwave system for a quantum current sensor based on single-sideband signal modulation is provided, comprising:

[0062] The radial structure adopts an Ω-shaped open-circuit slot, and the overall circuit structure and equivalent circuit are as follows: Figure 4 As shown, the Ω-shaped groove is set on a quartz glass substrate with a thickness of approximately 0.1 mm. This quartz material has good light transmittance and high-frequency dielectric properties, which is beneficial for achieving efficient microwave radiation.

[0063] The modulated microwave signal is transmitted via the main slot line, and a portion of the energy is coupled to the Ω-shaped open loop through a T-slot structure, thereby forming a locally enhanced alternating magnetic field in the central region. To optimize power distribution, the three ports of the T-slot are designed identically, with a slot width of 0.1 mm and matched characteristic impedances, ensuring high transmission efficiency. The Ω-shaped ring is used to radiate the microwave magnetic field, with the strongest magnetic field in its central region, which can meet the requirements for effective driving of the NV color center. The overall characteristic impedance of the radiation structure is controlled within 50Ω, the operating frequency covers 2.87GHz±50MHz, and the magnetic field distribution is concentrated with low loss.

[0064] This embodiment further illustrates the system's pulse control and connection method. The system's TTL control signal is generated by an external function generator or arbitrary waveform generator. The pulse width is adjustable from 100 nanoseconds to 10 microseconds, the duty cycle is adjustable from 5% to 90%, and the repetition frequency ranges from 1Hz to 1MHz. The system supports trigger input and can achieve timing synchronization with modules such as lasers and data acquisition, facilitating experimental operation.

[0065] The system's signal source output is connected to the microwave bridge input via a coaxial RF cable, with the cable length controlled between 10 and 30 cm to minimize phase drift. The microwave bridge module uses a metal shielded housing, and internal components are connected via microstrip line soldering or semi-rigid RF wires. All interfaces use 50Ω standard SMA male connectors to avoid signal reflection and standing wave interference. All system modules are bolted to a grounded aluminum base plate. The arrangement of signal cables avoids paralleling or overlapping with power lines and digital control lines, thereby reducing electromagnetic crosstalk and ensuring stable system operation.

[0066] Furthermore, this embodiment illustrates the system calibration process. The system is calibrated using a standard magnetic field source, adjusting the output gain of the power amplifier to achieve a magnetic field strength of 2.9 mT ± 0.1 mT at the center of the Ω-shaped ring. During verification, a lock-in amplifier was used to measure the fluorescence signal of the NV color center, achieving a signal-to-noise ratio greater than 20 dB, and the frequency response test covered the 2.82–2.92 GHz band, meeting experimental requirements.

[0067] It should be noted that the method in this embodiment is based on a TTL-controlled dual-mode microwave modulation structure. The carrier wave is switched to a direct or modulated channel via TTL control, achieving programmable dual-mode microwave output. An Ω-shaped open-circuit slot combined with a T-shaped coupling optimization structure is used. The radiation structure employs an Ω-shaped open-circuit slot combined with a symmetrical T-shaped slot structure, offering advantages such as impedance matching, high transmission efficiency, and concentrated magnetic field. Compared to existing literature using microstrip rings or solenoids, this slot structure offers better microwave integration and microfabrication compatibility. The microwave radiation structure based on the Ω-shaped open-circuit slot and symmetrical T-shaped coupling structure, mounted on a quartz glass substrate, exhibits high-frequency response and local magnetic field enhancement capabilities.

[0068] In this invention, the PIN switch is used to control and switch the microwave signal path based on TTL signals in the microwave bridge, while the power amplifier is located between the microwave bridge and the radiating structure to increase the amplitude of the modulation signal to meet the power requirements for driving the radiating magnetic field. Both can be included in the system structure composition.

[0069] In this invention, "50Ω" refers to a matching load with a characteristic impedance of 50 ohms connected to the end of the system. This is a commonly used impedance matching standard in high-frequency circuits, used to maintain impedance continuity with the system's front-end RF link, thereby preventing reflections and standing waves and improving signal transmission efficiency. This load structure can be an integrated surface-mount resistor, an external matching load device, or a standard 50Ω terminal connected to the terminal instrument interface. The actual structure can be selected according to the system package, but its core feature is meeting the 50Ω characteristic impedance requirement.

[0070] Example 5, refer to Figures 2-4 This is one embodiment of the present invention, which provides a microwave method for a quantum current sensor based on single-sideband signal modulation, comprising: outputting a high-frequency carrier signal and a low-frequency baseband signal through a signal source;

[0071] The microwave bridge receives the high-frequency carrier signal and the low-frequency baseband signal, and performs single-sideband modulation on the two to generate a single-sideband microwave signal.

[0072] The microwave bridge is controlled to switch between the modulation path and the through path to output the signal of the selected path;

[0073] The single-sideband microwave signal is received by the radiating structure and converted into an alternating magnetic field applied to the quantum state working medium.

[0074] The equivalent circuit of the radiating structure consists of multiple series and parallel RLC element networks. The input section is modeled by a series branch consisting of R1 and L1 to model the transmission characteristics of the main slot line. The middle section consists of a parallel resonant network composed of two symmetrical series LC branches, each of which contains C1–L2 and C2–L2 respectively, and is connected at the midpoint by resistor R2 to simulate the energy coupling and loss characteristics of the Ω-type structure. The output is a series branch containing R3 and L3 to model the radiating load behavior at the end of the ring structure.

[0075] Spectrum analyzer measurements show that unwanted sideband components in the signal after single-sideband modulation are effectively suppressed, with a sideband suppression ratio better than 25dB. The system output power is increased by about 10%. In addition, the microwave pulse output after modulation based on the 2.87GHz carrier has a significantly improved fluorescence readout signal-to-noise ratio in the NV color center excitation experiment, with an SNR improvement of about 35dB measured using a lock-in amplifier.

[0076] Currently, it has been observed through an oscilloscope that the carrier switching response time between the "straight path" and the "modulation path" under TTL pulse control is approximately 10ns. When tested with a frequency synthesizer, the system has precise pulse gating capability.

[0077] In actual experiments, microwave output switching between the reference channel and the modulation channel under time-controllable conditions has been achieved, which can be used to distinguish between π / 2 pulses and reference pulses in quantum systems.

[0078] Near-field measurements were performed at the end of the system using a standard magnetic field probe. The magnetic field strength at the center of the Ω-shaped loop reached 2.9 mT (±0.1 mT), which meets the theoretical design value. Compared with the case without the T-slot structure, the magnetic field strength at the center is increased by more than 20% under the same power input.

[0079] The signal sources mainly include a high-frequency carrier signal source and a low-frequency baseband signal source. A vector signal generator is used as the high-frequency carrier signal source to generate a stable high-frequency carrier signal with a frequency range covering 1GHz to 4GHz, which can be precisely set to 2.87GHz to meet the resonant modulation requirements of the quantum system. An arbitrary waveform generator is used as the low-frequency baseband signal source to generate a modulated low-frequency baseband signal with dual-channel independent control capability. It can generate orthogonal signals with the same amplitude and frequency but a 90° phase difference, and supports free switching between continuous waveforms and pulse waveforms.

[0080] The microwave bridge mainly includes a vector signal source, an arbitrary waveform generator, microwave switching devices, a 1-to-2 90° phase difference power divider, multiple frequency synthesizers, and multiple 0° phase difference power synthesizers (microwave bridge structure is attached). Figure 3 A vector signal generator produces a high-frequency local oscillator signal, which serves as the carrier source for microwave modulation. Simultaneously, an arbitrary waveform generator outputs two orthogonal low-frequency baseband signals with the same frequency and amplitude but a 90° phase difference, used as modulation signals. The carrier signal first passes through a TTL-controlled high-speed microwave switch to achieve time-division control of the signal path. When the TTL signal is high, the high-frequency carrier signal does not participate in modulation and is directly output through a 0° phase difference power combiner channel as a reference or direct path. When the TTL signal is low, the high-frequency carrier signal is guided to a 1-to-2 90° phase difference power divider, which divides the carrier signal into two equal amplitudes and applies a 90° phase difference, forming two mutually orthogonal high-frequency signals. Simultaneously, the two channels of the arbitrary waveform generator output two baseband orthogonal signals with a 90° phase difference, which are then I / Q mixed with the two high-frequency carrier signals through two independent mixers to obtain two mixed output signals. Subsequently, the two mixed output signals are fed into a 0° phase difference power combiner for in-phase synthesis, thus forming a single-sideband microwave signal that effectively filters out the carrier and non-target sideband components. Finally, this modulated single-sideband signal is fed into the final stage power combiner, where it is combined with a high-frequency through-carrier signal output from the TTL control channel to achieve programmable dual-mode output. The synthesized signal is further amplified by a power amplifier before being sent to subsequent modules in the system.

[0081] The radial structure adopts an Ω-shaped open-circuit slot (the overall structure of the radial structure circuit and the equivalent circuit of the radial structure are shown in the attached figure). Figure 4The system is mounted on a 0.1 mm thick quartz glass substrate. The quartz material possesses excellent light transmittance and high-frequency dielectric properties. The modulated microwave signal is transmitted via the main slot line, and a portion of the energy is coupled to an Ω-shaped loop through a T-slot structure, forming a localized alternating magnetic field. To optimize power distribution, the three ports of the T-slot are identical, with a slot width of 0.1 mm, characteristic impedance matching, and high transmission efficiency. The Ω-shaped loop radiates the microwave magnetic field, with the highest magnetic field strength in the central region, effectively driving the NV color center. The overall impedance is controlled within 50 Ω, the operating frequency covers 2.87 GHz ± 50 MHz, the magnetic field distribution is concentrated, and losses are low.

[0082] The TTL signal is generated by an external function generator or arbitrary waveform generator, with an adjustable pulse width of 100ns to 10μs, a duty cycle of 5% to 90%, and a repetition frequency range of 1Hz to 1MHz. The system supports trigger input to achieve timing synchronization with modules such as the laser and data acquisition unit.

[0083] The signal source output is connected to the microwave bridge input via a coaxial RF cable, with the cable length controlled between 10 and 30 cm to reduce phase drift. The microwave bridge module uses a metal shielded housing, and the internal components are connected via microstrip line soldering or semi-rigid wire connection. All interfaces are 50Ω SMA male connectors to avoid reflection and standing wave interference. All modules are bolted to an aluminum base plate, which is grounded. Signal cables are routed away from power lines and digital control lines to reduce electromagnetic crosstalk.

[0084] The system was calibrated using a standard magnetic field source, and the magnetic field strength at the center of the Ω-shaped ring was adjusted to 2.9 mT ± 0.1 mT by adjusting the power amplifier gain. During verification, a lock-in amplifier was used to measure the fluorescence signal of the NV color center; the signal-to-noise ratio should be >20 dB, and the frequency response test should cover the 2.82-2.92 GHz band.

[0085] This embodiment also provides an electronic device applicable to a microwave method for a quantum current sensor based on single-sideband signal modulation, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the microwave method for a quantum current sensor based on single-sideband signal modulation as proposed in the above embodiment.

[0086] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements a microwave method for a quantum current sensor based on single-sideband signal modulation as proposed in the above embodiments.

[0087] The storage medium proposed in this embodiment belongs to the same inventive concept as the microwave method for realizing a quantum current sensor based on single-sideband signal modulation proposed in the above embodiments. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0088] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0089] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A microwave system for a quantum current sensor based on single-sideband signal modulation, characterized in that: include, A signal source is used to simultaneously output a high-frequency carrier signal and a low-frequency baseband signal, wherein the high-frequency carrier signal serves as the carrier source for modulation and the low-frequency baseband signal serves as the modulation signal. A microwave bridge, connected to the signal source, is used to receive the high-frequency carrier signal and the low-frequency baseband signal, modulate them to form a single-sideband microwave signal, and switch the transmission path of the high-frequency carrier signal to the modulation path or the direct path when a control signal is received. A radiating structure, connected to the microwave bridge, is used to receive the single-sideband microwave signal and emit it as an alternating magnetic field to act on the working region of the quantum system.

2. The microwave system for a quantum current sensor based on single-sideband signal modulation as described in claim 1, characterized in that: The signal source is configured to output two mutually orthogonal low-frequency baseband signals, and the two low-frequency baseband signals are respectively combined with the high-frequency carrier signal to form mutually orthogonal modulation signal components for generating single-sideband microwave signals.

3. The microwave system for a quantum current sensor based on single-sideband signal modulation as described in claim 2, characterized in that: The microwave bridge selectively switches the transmission path of the high-frequency carrier signal through a control signal, switching the output mode between the modulation path and the direct path.

4. The microwave system for a quantum current sensor based on single-sideband signal modulation as described in claim 3, characterized in that: The radiation structure is configured to create a locally enhanced alternating magnetic field within the target region of the quantum system.

5. A microwave system for a quantum current sensor based on single-sideband signal modulation as described in claim 4, characterized in that: The radiation structure includes a main slot line disposed on an insulating substrate and an Ω-shaped open-circuit slot line coupled to the main slot line. The Ω-shaped open-circuit slot line is configured to form a locally enhanced alternating magnetic field in its central region and apply the magnetic field to the quantum state working medium located in that region.

6. The microwave system for a quantum current sensor based on single-sideband signal modulation as described in claim 5, characterized in that: The main slot line and the Ω-shaped open-circuit slot line are coupled by a T-shaped slot, and the structure and characteristic impedance of each port of the T-shaped slot are matched.

7. The microwave system for a quantum current sensor based on single-sideband signal modulation as described in claim 6, characterized in that: The insulating substrate of the radiating structure is made of a transparent material with a high dielectric constant.

8. The microwave system for a quantum current sensor based on single-sideband signal modulation as described in claim 7, characterized in that: The microwave bridge and the radiating structure are connected by a characteristic impedance-matched radio frequency coaxial cable, the interface of which is a standard radio frequency connector.

9. A microwave system for a quantum current sensor based on single-sideband signal modulation as described in claim 8, characterized in that: The system is connected at its end to a matching load with a characteristic impedance of 50 ohms.

10. A microwave method for a quantum current sensor based on single-sideband signal modulation, employing a microwave system for a quantum current sensor based on single-sideband signal modulation as described in any one of claims 1 to 9, characterized in that, include: The signal source outputs a high-frequency carrier signal and a low-frequency baseband signal. The microwave bridge receives the high-frequency carrier signal and the low-frequency baseband signal, and performs single-sideband modulation on the two to generate a single-sideband microwave signal. The microwave bridge is controlled to switch between the modulation path and the through path to output the signal of the selected path; The single-sideband microwave signal is received by the radiating structure and converted into an alternating magnetic field applied to the quantum state working medium.

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