A differential-based diamond nv color center fluorescence detection method and quantum sensor

Abstract

The application provides a differential-based diamond NV color center fluorescence detection method and a quantum sensor, wherein fluorescence generated by the diamond is separated from laser mixed in the fluorescence, and then is collected respectively and is subjected to differential processing; during the initial and detection processes, the laser is subjected to gain adjustment, so that the difference is kept to be zero, and the detection of the fluorescence change amount is converted into the change amount of the gain through an output gain increment; on one hand, when the fluorescence is collected, the laser is separated for differential processing, so that the structure elements can be simplified and unnecessary noise interference can be reduced; on the other hand, the gain increment of the laser relative to the fluorescence is used to represent the fluorescence detection value, so that common-mode noise changing with the continuous change of the fluorescence during the detection process can be better inhibited, and the measurement accuracy of the system is improved.

Description

Technical Field

[0001] This invention relates to the field of quantum precision measurement, and in particular to a differential-based method for detecting the fluorescence of diamond NV color centers and a quantum sensor. Background Technology

[0002] In precision measurement methods based on diamond NV centers, a laser is irradiated onto the diamond to induce fluorescence. The fluorescence is then collected to measure physical quantities such as magnetic fields and temperature. During fluorescence collection, the fluorescence signal is affected by common-mode noise, typically high-frequency noise, caused by fluctuations in laser intensity. Noise reduction is necessary when processing the fluorescence signal. Traditional noise reduction methods employ differential processing, where the laser beam is split, one beam is applied to the diamond, and the other serves as a reference signal. A balanced detector is then used to detect the signals, and the data is differentially processed to suppress common-mode noise caused by laser intensity fluctuations. Another approach involves irradiating the diamond with both laser and microwave radiation in one cycle, detecting the fluorescence, and then collecting the fluorescence in one cycle by activating only the laser. Differential processing is then applied to the fluorescence from the two cycles to suppress common-mode noise caused by laser intensity fluctuations.

[0003] Existing noise suppression methods mostly employ direct subtraction for differential processing. However, when the detected fluorescence changes continuously, such as when the magnetic field around the diamond changes, the common-mode noise in the fluorescence detection will also change. Therefore, the suppression effect of the existing differential processing method for common-mode noise suppression is poor. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a differential-based method for detecting the fluorescence of diamond NV color centers and a quantum sensor, which solves the problem that the differential noise reduction method in the prior art has poor suppression effect when suppressing common-mode noise that changes with the detection value.

[0005] To achieve the above and other related objectives, this invention provides a method for detecting the fluorescence of diamond NV centers based on differential modulation, comprising:

[0006] A1. In a magnetic field-free environment, a diamond containing NV color centers is irradiated with laser; the fluorescence produced by the diamond and the laser mixed in the fluorescence are separated and collected separately, and the gain of the collected laser is adjusted. An initial adjustment gain is set, and the adjusted laser signal and the collected fluorescence signal are differentially processed to obtain a differential signal. By adjusting the power of the emitted laser and / or the initial adjustment gain, the differential signal is made zero.

[0007] A2, under the laser power adjusted in step A1 of maintaining diamond irradiation, continuously collect the separated laser signal and fluorescence signal, and continuously acquire the differential signal; adjust the adjustment gain of the collected laser signal according to the differential signal so that the differential signal is equal to zero, and acquire the incremental signal of the current adjustment gain relative to the initial gain to characterize the real-time detection value of the fluorescence in the current environment.

[0008] A3. While continuing step A2, transfer the diamond to the test environment with or without a magnetic field, and use the acquired incremental signal to characterize the real-time detection value of the fluorescence of the current environment.

[0009] Furthermore, in steps A1-A3, microwave radiation is applied to the diamond.

[0010] To achieve the above and other related objectives, the present invention also provides a quantum sensor based on differential modulation, the sensor comprising: a diamond containing NV color centers, a laser excitation and fluorescence collection unit, and a differential modulation unit;

[0011] The laser excitation and fluorescence collection unit is used to emit laser light to the diamond, separate the fluorescence generated by the diamond and the laser light mixed in the fluorescence and collect them separately, and send the collected laser signal and fluorescence signal to the differential adjustment unit.

[0012] The differential adjustment unit is connected to the laser excitation and fluorescence collection unit. It is used to adjust the gain of the received laser signal, perform differential processing on the adjusted laser signal and the fluorescence signal, adjust the adjustment gain of the received laser signal according to the differential signal so that the differential signal is equal to zero, and then obtain the incremental signal of the current adjustment gain relative to the initial gain to characterize the real-time detection value of the fluorescence in the current environment.

[0013] Furthermore, the laser excitation and fluorescence collection unit includes a laser generator, a separation mechanism, and a detector. The laser emitted by the laser generator irradiates the diamond, and the fluorescence generated by the diamond and the laser mixed in the fluorescence are separated by the separation mechanism and detected and collected by the detector.

[0014] Furthermore, the separation mechanism includes a two-color filter, through which the mixed light of laser and fluorescence is separated by reflection and transmission; or the separation mechanism includes an optical circulator and a two-color filter, through which the laser generated by the laser generator is transmitted from the first port of the optical circulator to the second port, and from the second port to the two-color filter, after being reflected by the two-color filter, it irradiates the diamond, and after the mixed light is transmitted through the two-color filter, fluorescence is separated, and after being reflected by the two-color filter, it is transmitted from the second port of the optical circulator to the third port, and the laser is separated from the third port;

[0015] Furthermore, the separation mechanism includes a beam splitter and two filters. The mixed light is split into a reflected beam and a transmitted beam after passing through the beam splitter, and then filtered one-to-one by the two filters to filter out laser and fluorescence.

[0016] Furthermore, the differential adjustment unit includes a gain adjustment unit and a differential unit. The laser excitation and fluorescence collection unit sends a laser signal to the gain adjustment unit and a fluorescence signal to the differential unit. The gain adjustment unit adjusts the gain of the laser signal according to the received gain adjustment signal and sends the adjusted laser signal to the differential unit. The differential unit performs differential processing on the adjusted laser signal and the fluorescence signal and sends a gain adjustment signal to the gain adjustment unit according to the differential signal to adjust the adjustment gain of the laser signal so that the differential signal is equal to zero.

[0017] Furthermore, the differential unit obtains the incremental signal of the current adjusted gain relative to the initial gain, which is used to characterize the real-time detection value of fluorescence.

[0018] Furthermore, the differential adjustment unit also includes an integration unit. The differential unit is further configured to, when the differential signal is not zero, after adjusting the adjustment gain of the laser signal to make the differential signal zero, acquire the incremental signal of the current gain relative to the gain before the current adjustment, and send the incremental signal as a processing signal to the integration unit; when the differential signal is zero, after adjusting the adjustment gain of the laser signal to keep the differential signal zero, send the differential signal as a processing signal to the integration unit; the integration unit performs real-time integration processing on the processing signal to obtain a real-time integration value, which is used to characterize the real-time detection value of fluorescence.

[0019] Furthermore, it also includes a microwave radiating unit for radiating microwaves onto the diamond.

[0020] As described above, the differential-based method for detecting the fluorescence of diamond NV centers and the quantum sensor of the present invention have the following advantages: By separating the fluorescence generated by the diamond from the laser mixed in the fluorescence, and collecting them separately for differential processing, the laser gain is adjusted during the initial stage and the detection process to keep the difference zero. The fluorescence change is converted into a gain change by outputting the gain increment to characterize the fluorescence detection value. On the one hand, separating the laser for differential processing during fluorescence collection simplifies the structural components and reduces unnecessary noise interference. On the other hand, using the gain increment of the laser relative to the fluorescence to characterize the fluorescence detection value can better suppress the common-mode noise that changes with the continuous change of fluorescence during the detection process and improve the measurement accuracy of the system. Attached Figure Description

[0021] Figure 1 The diagram shows a flowchart of the differential-adjustment-based fluorescence detection method for diamond NV color centers according to the present invention.

[0022] Figure 2 The diagram shows a quantum sensor structure based on differential adjustment in Embodiment 1 of the present invention.

[0023] Figure 3 The diagram shows a quantum sensor structure based on differential adjustment in Embodiment 2 of the present invention.

[0024] Figure 4 The diagram shown is a schematic of a quantum sensor structure based on differential modulation in Embodiment 3 of the present invention.

[0025] Component labeling: 1—Diamond; 2—Laser excitation and fluorescence collection unit; 21—Laser generator; 22—Detector; 23—Dual-color filter; 24—Optical circulator; 25—Filter; 26—Beam splitter; 3—Differential adjustment unit; 31—Gain adjustment unit; 32—Differential unit; 33—Integrator; 4—Microwave source; 5—Microwave antenna. Detailed Implementation

[0026] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0027] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0028] like Figure 1 As shown, this invention provides a method for detecting the fluorescence of diamond NV centers based on differential modulation, comprising:

[0029] A1. In a magnetic field-free environment, a diamond containing NV color centers is irradiated with laser; the fluorescence produced by the diamond and the laser mixed in the fluorescence are separated and collected separately, and the gain of the collected laser is adjusted. An initial adjustment gain is set, and the adjusted laser signal and the collected fluorescence signal are differentially processed to obtain a differential signal. By adjusting the power of the emitted laser and / or the initial adjustment gain, the differential signal is made zero.

[0030] A2, under the laser power adjusted in step A1 of maintaining diamond irradiation, continuously collect the separated laser signal and fluorescence signal, and continuously acquire the differential signal; adjust the adjustment gain of the collected laser signal according to the differential signal so that the differential signal is equal to zero, and acquire the incremental signal of the current adjustment gain relative to the initial gain to characterize the real-time detection value of the fluorescence in the current environment.

[0031] A3. While continuing step A2, transfer the diamond to the test environment with or without a magnetic field, and use the acquired incremental signal to characterize the real-time detection value of the fluorescence of the current environment.

[0032] By adjusting the difference between fluorescence and laser light to zero in step A1, and continuously adjusting the gain of the laser path based on this difference during subsequent detection to maintain a zero difference, this method effectively addresses the problem of poor common-mode noise suppression in existing direct difference methods caused by continuous changes in fluorescence during detection. In this method, given that the amplitude of common-mode noise in the detected fluorescence is positively correlated with the fluorescence amplitude, mathematical knowledge shows that the difference between the detected fluorescence and common-mode noise is positively correlated with the laser gain adjustment. Therefore, by converting fluorescence changes into changes in laser gain adjustment, common-mode noise can be effectively suppressed, improving measurement accuracy.

[0033] The magnetic field referred to in this invention includes the Earth's magnetic field. The increment of gain is obtained by subtracting two gain values.

[0034] Example 1: The aforementioned differential modulation-based fluorescence detection method is used to measure the magnetic field in the environment under test. This can be achieved using methods such as... Figure 2 The quantum sensor shown is used to achieve this, such as Figure 2As shown, the quantum sensor includes: a diamond 1 containing NV color centers, a laser excitation and fluorescence collection unit 2, and a differential adjustment unit 3. The laser excitation and fluorescence collection unit 2 includes a laser generator 21, a separation mechanism, and a detector 22. The laser emitted by the laser generator 21 irradiates the diamond 1. The fluorescence generated by the diamond 1 and the laser mixed in the fluorescence are separated by the separation mechanism and then detected and collected by the detector 22. The differential adjustment unit 3 includes a gain adjustment unit 31 and a differential unit 32. The laser excitation and fluorescence collection unit 2 sends a laser signal to the gain adjustment unit 31 and a fluorescence signal to the differential unit 32. The gain adjustment unit 31 adjusts the gain of the laser signal according to the received gain adjustment signal and sends the adjusted laser signal to the differential unit 32. The differential unit 32 performs differential processing on the adjusted laser signal and the fluorescence signal, and sends a gain adjustment signal to the gain adjustment unit 31 according to the differential signal to adjust the adjustment gain of the laser signal so that the differential signal is equal to zero. It also obtains the increment signal of the current adjustment gain relative to the initial gain, which is used to characterize the real-time detection value of the fluorescence.

[0035] Can Figure 2 As shown, two detectors are used to collect laser and fluorescence respectively; alternatively, a single detector, such as a balanced photodetector, can be used to detect laser and fluorescence and output the laser and fluorescence signals to the differential adjustment unit 3.

[0036] The separation mechanism includes a two-color filter 23. The mixed light is reflected by the filter, and fluorescence is transmitted, thereby achieving the separation of the laser and fluorescence. In one embodiment, in... Figure 2 Based on the embodiment shown, the separation mechanism also includes, for example: Figure 3 The filter 25 shown is set at the optical path output end of the dichroic filter 23 and is used to further filter the laser and fluorescence separated by the dichroic filter to improve the collection efficiency.

[0037] Adopting such Figure 2The steps for measuring the magnetic field in the test environment using the quantum sensor are as follows: The quantum sensor is placed in a magnetic-free environment, and a diamond is irradiated with a 532nm laser. The diamond fluoresces under the influence of the laser, a magnetic field, or only the laser (when the magnetic field is zero). The laser power and / or gain are adjusted as in step A1, making the differential signal zero. Then, while maintaining the adjusted laser power, step A2 is continued. While continuing step A2, the quantum sensor is transferred to the test environment (if the range of movement allows, only the diamond and at least part of the laser excitation optical path and at least part of the mixed optical transmission optical path connected to it can be transferred; if optical fiber is used for optical transmission, only the diamond and the fiber optic connector connected to it can be transferred). The incremental signal of the current adjusted gain relative to the initial gain is obtained, representing the real-time detection value of the fluorescence in the current environment. The real-time incremental signal and a pre-calibrated calibration curve of the incremental signal versus the magnetic field strength are used to obtain the real-time magnetic field strength. This method of the present invention allows for the continuous measurement of the magnetic field strength in different environments or changing magnetic field strengths.

[0038] Example 2: This example differs from Example 1 in that, in steps A1-A3 above, the diamond is further irradiated with microwaves. The diamond fluoresces under the influence of laser, microwave, magnetic field, or laser and microwave (when the magnetic field is zero). An example is used as follows... Figure 3 The quantum sensor shown measures the magnetic field of the environment under test. Unlike the quantum sensor in Embodiment 1, it also uses a microwave radiation unit to radiate microwaves onto the diamond. The microwave radiation unit includes at least a microwave source 4 and a microwave antenna 5. The microwaves generated by the microwave source 4 are transmitted to the microwave antenna 5. The figure shows that the microwave antenna 5 is a helical antenna, which is sleeved on the outside of the diamond 1 and radiates microwaves onto the diamond 1. Its separation mechanism is also different, and the differential adjustment unit 3 is different. The rest are the same, and will not be described in detail here.

[0039] The separation mechanism in this embodiment includes an optical circulator 24, a dichroic filter 23, and a filter 25. The laser generated by the laser generator 21 is transmitted from the first port of the optical circulator 24 to the second port, and then from the second port to the dichroic filter 23. The laser reflected by the dichroic filter irradiates the diamond 1. The mixed light is transmitted through the dichroic filter 23 and separated into fluorescence and laser. The separated laser light is then transmitted from the second port of the optical circulator 24 to the third port and output from the third port. The separated laser and fluorescence are then filtered separately by the filter 25 and collected by the detector 22.

[0040] The differential adjustment unit 3 differs from that in Embodiment 1 in that it further includes an integration unit 33. The differential unit 32 is also configured to, when the differential signal is not zero, after adjusting the adjustment gain of the laser signal to make the differential signal zero, acquire the incremental signal of the current gain relative to the gain before the current adjustment, and send the incremental signal as a processing signal to the integration unit 33; when the differential signal is zero, after adjusting the adjustment gain of the laser signal to keep the differential signal zero, send the differential signal as a processing signal to the integration unit 33; the integration unit 33 performs real-time integration processing on the processing signal to obtain a real-time integration value, which is used to characterize the real-time detection value of fluorescence.

[0041] Example 3: The difference between this example and Example 1 lies in the separation mechanism, such as... Figure 4 As shown, the separation mechanism includes a beam splitter 26 and two filters 25. The mixed light is split into a reflected beam and a transmitted beam by the beam splitter 26, and then filtered by their respective filters 25 to separate the laser and fluorescence, thereby achieving the separation of laser and fluorescence. Preferably, the intensity of the separated fluorescence beam is greater than the intensity of the separated laser beam.

[0042] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for detecting the fluorescence of diamond NV centers based on differential modulation, characterized in that, The method includes: A1. In a magnetic field-free environment, a diamond containing NV color centers is irradiated with laser; the fluorescence produced by the diamond and the laser mixed in the fluorescence are separated and collected separately, and the gain of the collected laser is adjusted. An initial adjustment gain is set, and the adjusted laser signal and the collected fluorescence signal are differentially processed to obtain a differential signal. By adjusting the power of the emitted laser and / or the initial adjustment gain, the differential signal is made zero. A2, under the laser power adjusted in step A1 of maintaining diamond irradiation, continuously collect the separated laser signal and fluorescence signal, and continuously acquire the differential signal; adjust the adjustment gain of the collected laser signal according to the differential signal so that the differential signal is equal to zero, and acquire the incremental signal of the current adjustment gain relative to the initial gain to characterize the real-time detection value of the fluorescence in the current environment. A3. While continuing step A2, transfer the diamond to the test environment with or without a magnetic field, and use the acquired incremental signal to characterize the real-time detection value of the fluorescence of the current environment.

2. The method for detecting the fluorescence of diamond NV color centers based on differential adjustment according to claim 1, characterized in that: In steps A1-A3, microwave radiation is also applied to the diamond.

3. A quantum sensor based on differential modulation, characterized in that, The sensor includes: a diamond containing NV color centers (1), a laser excitation and fluorescence collection unit (2), and a differential adjustment unit (3); The laser excitation and fluorescence collection unit (2) is used to emit laser to the diamond (1), and to separate and collect the fluorescence generated by the diamond (1) and the laser mixed in the fluorescence, and send the collected laser signal and fluorescence signal to the differential adjustment unit (3). The differential adjustment unit (3) is connected to the laser excitation and fluorescence collection unit (2) and is used to adjust the gain of the received laser signal, perform differential processing on the adjusted laser signal and the fluorescence signal, adjust the adjustment gain of the received laser signal according to the differential signal so that the differential signal is equal to zero, and then obtain the incremental signal of the current adjustment gain relative to the initial gain to characterize the real-time detection value of the fluorescence in the current environment.

4. The quantum sensor based on differential modulation according to claim 3, characterized in that: The laser excitation and fluorescence collection unit (2) includes a laser generator (21), a separation mechanism, and a detector (22). The laser emitted by the laser generator (21) irradiates the diamond (1). The fluorescence generated by the diamond (1) and the laser mixed in the fluorescence are separated by the separation mechanism and detected and collected by the detector (22).

5. The quantum sensor based on differential modulation according to claim 4, characterized in that: The separation mechanism includes a two-color plate (23), where the mixed light of laser and fluorescence is separated by reflection and transmission through the two-color plate (23); or the separation mechanism includes an optical circulator (24) and a two-color plate (23), where the laser generated by the laser generator (21) is transmitted from the first port of the optical circulator (24) to the second port, and then from the second port to the two-color plate (23), where it is reflected by the two-color plate (23) and then irradiates the diamond (1). The mixed light is transmitted through the two-color plate (23) and then the fluorescence is separated. After being reflected by the two-color plate (23), the fluorescence is transmitted from the second port of the optical circulator (24) to the third port, where the laser is separated.

6. The quantum sensor based on differential modulation according to claim 4, characterized in that: The separation mechanism includes a beam splitter (26) and two filters (25). After the mixed light passes through the beam splitter (26), it is divided into a reflected beam and a transmitted beam, which are then filtered one-to-one by the two filters (25) to filter out laser and fluorescence.

7. The quantum sensor based on differential modulation according to claim 3, characterized in that: The differential adjustment unit (3) includes a gain adjustment unit (31) and a differential unit (32). The laser excitation and fluorescence collection unit (2) sends a laser signal to the gain adjustment unit (31) and a fluorescence signal to the differential unit (32). The gain adjustment unit (31) adjusts the gain of the laser signal according to the received gain adjustment signal and sends the adjusted laser signal to the differential unit (32). The differential unit (32) performs differential processing on the adjusted laser signal and the fluorescence signal and sends a gain adjustment signal to the gain adjustment unit (31) according to the differential signal to adjust the adjustment gain of the laser signal so that the differential signal is equal to zero.

8. The quantum sensor based on differential modulation according to claim 7, characterized in that: The differential unit (32) obtains the incremental signal of the current adjustment gain relative to the initial gain, which is used to characterize the real-time detection value of fluorescence.

9. The quantum sensor based on differential modulation according to claim 7, characterized in that: The differential adjustment unit (3) further includes an integration unit (33). The differential unit (32) is also configured to, when the differential signal is not zero, after adjusting the adjustment gain of the laser signal to make the differential signal zero, obtain the incremental signal of the current gain relative to the gain before this adjustment, and send the incremental signal as a processing signal to the integration unit (33). When the differential signal is zero, after adjusting the adjustment gain of the laser signal to keep the differential signal zero, send the differential signal as a processing signal to the integration unit (33). The integration unit (33) performs real-time integration processing on the processing signal to obtain a real-time integration value, which is used to characterize the real-time detection value of fluorescence.

10. The quantum sensor based on differential modulation according to claim 3, characterized in that: It also includes a microwave radiation unit for radiating microwaves onto the diamond (1).

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