WO2019103663A1

WO2019103663A1 - Precision solid-state continuously acting quantum gyroscope based on a spin ensemble in diamond

Info

Publication number: WO2019103663A1
Application number: PCT/RU2019/050002
Authority: WO
Inventors: Вадим Владиславович ВОРОБЬЕВ; Владимир Владимирович СОШЕНКО; Степан Викторович БОЛЬШЕДВОРСКИЙ; Алексей Владимирович АКИМОВ; Андрей Николаевич СМОЛЯНИНОВ
Original assignee: Общество С Ограниченной Ответственностью "Сенсор Спин Технолоджис"
Priority date: 2017-11-23
Filing date: 2019-01-15
Publication date: 2019-05-31
Also published as: RU2684669C1

Abstract

Use: carrying out measurements using a quantum gyroscope. The essence of the invention lies in measuring rotation in space by means of a rotation sensor comprising a diamond slab having colour centres, wherein the measuring process includes the following steps: calibrating the sensor by transitioning the electron spin system of the colour centres into a state ms=0 with an electron spin projection onto the NV centre axis that is equal to zero; bringing the sensor into a state sensitive to rotation by applying a resonant radio frequency to a nuclear spin system in a state ms=0, mi=0; minimizing rotation measurement error by modulating microwave radiation frequencies in the vicinity of two resonant frequencies corresponding to different electron spin values, wherein the electron spin response is registered on the basis of the fluorescence signal of the diamond slab at the modulation frequencies and a correction frequency is selected for the microwave signal on the basis of the error signal measured, restoring the radiation frequency to the maxima of the resonant circuits; calculating, with a set periodicity, the angular velocity of rotation of the sensor as the difference between the constantly сontrolled frequency of the microwave radiation and the known value of the quadrupole splitting of the nuclear spin, wherein the nuclear spin response is registered on the basis of the fluorescence signal of the diamond slab at the modulation frequency and a correction frequency is selected for the signal on the basis of the error signal measured, restoring the radiation frequency to the maximum of the resonant circuit. Technical result: making it possible to measure the absolute rotation of the sensitive element of the sensor.

Description

PRECISION HARDNESS QUANTUM GYROSCOPE OF CONTINUOUS ACTION BASED ON A SPIN ENSEMBLE IN A DIAMOND

The invention relates to the field of gyroscopes, namely, to quantum gyroscopes.

The prior art patent RF N ° 2522596, published 02.10.2014, "Method for determining the angle of disorientation of diamond crystallites in a diamond composite", which describes a method for determining the angle of disorientation of diamond crystallites in a diamond composite. The method involves placing a diamond composite into an electron paramagnetic resonance (EPR) spectrometer resonator, measuring the EPR spectra of a nitrogen-vacancy NV defect in a diamond composite with different orientations of the diamond composite relative external magnetic field, comparing the obtained dependences of the EPR lines with the calculated positions of the NV defect EPR lines in a single crystal diamond in a magnetic field, determined by calculation. Then, by increasing the width of the EPR line in the diamond composite as compared to the width of the EPR line in a diamond single crystal, the angle of disorientation of the diamond crystallites is determined. The invention allows to determine the angle of misorientation of diamond crystallites in a diamond composite, provides high accuracy of measurements, as well as the possibility of optical detection of magnetic resonance (O DMR), which increases the sensitivity of measurements.

The prior art patent RF N ° 257047l, published 12.15.2014, "A method for determining the orientation of NV defects in a chip." The document describes a method for determining the orientation of NV defects in a diamond crystal. The method includes placing a diamond crystal sample in an external magnetic field, exposing the sample to microwave radiation, irradiating the sample working volume with focused laser radiation, exciting photoluminescence in the working volume of the sample, which records the signal of optically detected magnetic resonance (О ДМР), which is created by frequency sweep microwave radiation and modulation of the external magnetic field. The spectra of the ODMR of the NV defect in a diamond crystal are measured for different orientations of a diamond crystal with respect to an external magnetic field. The obtained dependences of the ODMR lines are compared with the calculated positions of the NV defect lines in a diamond crystal in a magnetic field. Then, the orientation of the NV defect is determined by the amount of deviation of the position of the NV lines of the defect from the calculated line positions. The invention solves the problem of determining the orientation of NV-defects in the crystal.

The prior art US patent N ° 9541610, published 08/04/2016, "The device and method for restoring a three-dimensional magnetic field using magnetic detection systems. The document discloses a system for magnetic detection of an external magnetic field. The system includes a diamond material with nitrogen vacancies (NV), containing many Nn centers, a magnetic field generator that generates a magnetic field, a radio frequency (RF) excitation source that provides radio frequency excitation, an optical excitation source that provides optical excitation, optical a detector that receives the optical signal emitted by the NV diamond material; and a controller. The controller is designed to calculate a control magnetic field, control a magnetic field generator to generate a control magnetic field, receive a light detection signal from an optical detector based on an optical signal in accordance with the sum of the generated control magnetic field and external magnetic field, store measurement data based on the received detection signal light and to calculate the vector of the external magnetic field based on the measurement data.

The prior art US patent J \ ° 8947080, published 12/09/2010, "Highly sensitive solid-state magnetometer." The patent describes a magnetometer for measuring the magnetic field, which may include a solid-state spin electronic system and a detector. The electron spin system can contain one or more electron spins that are located in the lattice, for example, NV centers in a diamond. The electron spins can be configured to receive optical excitation radiation and align with the magnetic field. The electron spins can be additionally induced to precess around the perceived magnetic field in response to external control, such as a radio frequency field, the spin precession frequency is linearly related to the magnetic field using the Zeeman shift of the electron spin energy levels. The detector can be configured to detect the output optical radiation from the electron spin to determine the Zeeman shift and, therefore, the magnetic field.

A disadvantage of the known solutions is the instability with respect to fluctuations of the radiation intensity, the inertia of the systems, the need for “a dark time”, during which the spin system is prepared for measurement and is therefore not sensitive to rotation.

Technical task

The technical problem solved by the invention is the measurement of the absolute rotation of the sensitive element of the sensor. The technical result is the same as the technical problem. Decision

To solve this problem, a method is proposed for measuring rotation in space using a rotation sensor containing a diamond plate with color centers, including the following steps,

• calibrate the sensor by transferring the electron spins of the color centers to the state with m _s = 0 with the projection of the electronic spins on the NV axis of the center equal to zero due to the constant impact on the diamond plate of the incoherent optical field, as well as the transfer of a part of the system of electronic spins corresponding to the projection of the nuclear spin mi = 1 hsch = - 1, color centers from the state m _s = 0 to the state m _s = (+/-) 1 and fr = (- / +) 1 with the projection of the indicated spins on the axis NV of the center equal to plus one | 0.1 }

| - 1, 1} and minus one | 0, - 1}

11 1} due to constant and simultaneous exposure of the diamond plate to optical incoherent radiation, two-frequency microwave radiation (UHF) and magnetic field, after which they transfer the nuclear spin system to the state gsb = 0 due to constant exposure of the diamond plate to radio frequency radiation (RF), which implements the transitions 11, - 1} <- "· 11,0}, | -1, 1} <-" · | -1,0},

• they bring the sensor into a state sensitive to rotation due to the application of a nuclear spin to the system, which is in the state m _s = 0, ft = 0, of resonant radio frequency radiation,

• minimize the measurement error of rotation of the modulated microwave frequencies in the vicinity of two resonant frequencies corresponding to different values of the electron spin, while registering the response of the electron spin on the fluorescence signal of the diamond plate at modulation frequencies and producing a correction frequency of the microwave signal based on the measured error signal returning the radiation frequency to the maxima of the resonant circuits,

• calculate, with a given periodicity, the angular velocity of the sensor rotation as the difference of the constantly monitored frequency of radio frequency radiation and the known value of quadrupole splitting of the nuclear spin, while constantly adjusting the frequency of radio frequency radiation by modulating the frequency of radio frequency radiation in the vicinity of the resonant frequency of the nuclear spin, while registering the response nuclear spin on the fluorescence signal of the diamond plate at the modulation frequency and produce a corrective hour totu signal based on the measured error signal that returns the frequency of the radiation to the maximum of the resonant circuit.

The method can be implemented with the following numerical characteristics. Using an optical system to direct radiation to a diamond plate, the pump power density on a diamond plate is not less than 10 W / mm ² , while creating a magnetic field on a diamond plate up to 20 Gauss, while providing an electromagnetic field on a diamond plate with a microwave antenna more than 90% uniformity, while using the optical system to ensure the efficiency of collecting fluorescence radiation of at least 10%.

To solve this problem, a rotation sensor on color centers is proposed, containing

• diamond plate with color centers,

• a source of incoherent light with an optical system for directing radiation onto a diamond plate, providing a pump power density sufficient to convert the system of electron spins of color centers to the state | 0, 1} with the projection of these spins on the axis NV of the center equal to zero due to the constant impact on the diamond plate incoherent optical field

• two sources of microwave radiation (microwave), modulated in amplitude and frequency, and a source of constant magnetic field to convert part of the system of electronic spins of color centers to the state with the projection of these spins on the axis of the NV center equal to one | 0, 1} <- "· | - 1, 1} and minus unit | 0, - 1} <- "· 11, - 1} due to the constant and simultaneous impact on the diamond plate of the dual-frequency microwave and magnetic field, while the source of the magnetic field is part of the antenna to create a microwave and is located in such a way that it creates a magnetic ole in the direction orthogonal to the maximum crystallographic axis orientation, or in the case of the three-axis embodiment generates a magnetic field in a direction not collinear axes ZM,

• two sources of radio frequency radiation for aligning the system of nuclear spins into a state sensitive to rotation in the sensor space due to constant exposure of the diamond plate to RF radiation, which implements transitions 11, - 1} 11.0}, | - 1, 1} | -1 , 0} • a photodetector for detecting the fluorescence of color centers in the diamond plate, as well as an optical system that allows you to direct the fluorescence from the diamond plate to the photodetector,

• a controller that, through control signals, generates feedback through constant microwave modulation in the vicinity of 2 resonant frequencies based on the magnitude of the electron spin response through recording fluorescence at the modulation frequency, as well as constant RF modulation in the vicinity of the nuclear spin resonance frequency through the registration of fluorescence at the modulation frequency, and calculates the angular velocity of rotation as the difference of the constantly monitored frequency of radio frequency radiation i, and the known value of quadrupole splitting of the nuclear spin.

The sensor can be performed with the following numerical characteristics of the constituent elements.

An incoherent radiation source with a spectrum in the range from 500 nm to 580nm, optical power at the source output of at least 0.1 W, an antenna for the microwave with a frequency range from 2.6 to 3 GHz, a source of a constant magnetic field, allowing to create a field on a diamond plate up to 20 can be used Gauss and having a temperature stability of more than 1 Gauss per hour, RF radiation sources operating in the range up to 10 MHz, a photo detector operating in the spectral range from 600 to 800 nm, having a frequency band of more than 1 MHz and providing a signal-to-w ratio mind is not less than 50 dB, while the magnitude of the projection of the magnetic field on the perpendicular to the selected axes of the crystal is not less than 0.3 G, and the quadrupole splitting of the nuclear spin is 4.95 MHz.

List of figures

The invention is illustrated by drawings.

FIG. 1 shows a block diagram of the device.

FIG. 2 shows three-dimensional structures for implementing the invention.

FIG. 3 shows a block diagram of a device for generating, recording and processing signals.

FIG. 4 shows the crystal structure of the NV defect in diamond.

FIG. 5 a) and b) respectively the layout of the energy levels inside the forbidden zone and a detailed image of the energy levels of the ground orbital state are shown. FIG. 6 shows an example of the hyperfine splitting observed in the optically detectable electron paramagnetic resonance.

FIG. 7 shows a diagram of the application of effects and the corresponding transitions in the work of a continuous gyroscope.

FIG. 8 shows the initialization of the nuclear spin.

FIG. 9 shows the evolution of the thermal state of the nuclear spin into a polarized state.

FIG. 10 depicts single-frequency synchronous detection. The black solid line in the center of the figure indicates the resonance circuit, the dotted one is the lock-in output of the amplifier. The figure also shows the forms of the modulating (above the average graph) and the modulated signal (to the right of the average graph).

In the figures introduced the following notation.

1. The source of a constant magnetic field along the axis NV.

2. Optical pumping radiation.

3. Diamond plate with NV-centers.

4. Optical pumping radiation + fluorescence emission from the IU centers.

5. Optical filter to cut off the pumping radiation.

6. Fluorescence of IU-centers.

7. Photo Detector.

8. RF antenna.

9. RF amplifier.

10. The adder signals from two RF generators.

11. RF amplitude modulator generator 13.

12. RF amplitude modulator generator 14.

13. A controlled sinusoidal signal generator operating in the 1..1 HMG (RF) range used in the nuclear spin polarization cycle.

14. Managed sinusoidal signal generator operating in the 1..10 MHz range (RF) used in the measurement cycle.

15. Device for generating, recording and processing signals.

16. A controlled oscillator of a microwave sinusoidal signal used in the cycle of polarization of the nuclear spin, adjusted to transitions | 0> - | +1> electronic spin.

17. The controlled oscillator of the microwave sinusoidal signal used in the cycle of polarization of the nuclear spin, adjusted to transitions | 0> - | -1> of the electronic spin. 53. Band-pass filter of the synchronous detector D _MW .

54. Delay line for adjusting synchronous detector A _MW -

Detailed solution description

The created technical solution includes a method of continuous measurement of the absolute speed of rotation of an object, as well as a device that allows continuous measurement of the absolute speed of rotation of an object in space based on an ensemble of NV - centers in a diamond. NV - the center in diamond - a defect in the crystal lattice of diamond, consisting of impurity nitrogen, and vacancies.

The advantages of such a system are high reliability, relatively small dimensions of the sensing element with a relatively higher performance in terms of accuracy compared with the known analogues. Moreover, due to natural features, this method allows for the detection of rotation with respect to three axes in one sensitive element using 4 selected crystallographic axes. Also, NV - centers are stable color centers at temperatures of 0-600 K.

The method of continuous measurement of the absolute speed of rotation is based on the determination of the projection of the total magnetization vector of nuclear spins of nitrogen defects ¹⁴ N OR of the ¹³ C carbon isotope in the crystal lattice of a diamond containing NV (-) color defects. In the proposed method, the total magnetization vector is brought into equilibrium stationary state by two opposite effects - “initialization” and “drive”. Bringing the system into rotation leads to a deviation of the magnetization vector from the equilibrium state — the balanced state of the nuclear spin changes the projection onto the quantization axis.

Estimates for measuring the error for such a device are at the level of 10 ^l -3 Grad / hour, being ahead of similarly compact methods for determining rotation by 1 -2 orders of magnitude.

The measurement method has the following simultaneous processes.

1. Initialization

2. Drive - flipping of the magnetization vector from state 0 to state 1.

3. Measurement of fluorescence

4. Feedback on the level of fluorescence on drive parameters

5. Binding the initialization parameters to the transition frequencies of the spin system to eliminate interference from external magnetic fields and temperature, as well as the simultaneous use of a degenerate triplet system of + 1.0, -1 nuclear spin to filter the contribution of the magnetic field. The design of the gyroscope on NV - centers in diamond consists of a diamond plate (3, Fig. 1). Diamond plate must have certain qualities on the content of color centers in it. In the case of C13 spins, there should be an increased C 13 content. In the case of N14, an increased content of NV color centers and a reduced C 13 content. The structure includes a green light source (23) (500-580nm), a laser or photodiode type, and an optical system for directing green radiation to a diamond plate; an optical filter (5) for filtering radiation (4) falling from diamond (3) into a waveguide (24) from pump radiation; a photodetector (7) for detecting fluorescence (6) of color centers in a diamond plate and optical elements (24), which allow directing fluorescence from a diamond plate to a photodetector (7).

The structure of the invention also includes a (resonant) microwave (22) and RF (8) antenna, a source of microwave (16-20) and RF (10-14) signals, which are necessary for effective interaction with the electronic and nuclear spins in the composition of the defects in diamond In addition, the device must contain a source of constant magnetic field (1) and an electronic computing system to control measurements (15).

Sources of RF and microwave signals are two-channel and consist of harmonic signal generators (13,14, 16,17) modulated in frequency and amplitude (using modulators 11,12, 18,19). The signal from the two channels is summed by adders (10.20) and is amplified by amplifiers (9.12) before being fed into the antennas.

Exercise

A rotation sensor based on the use of controlled precession of an ensemble of nuclear spins in a diamond crystal with a large number of Nn centers in it. The NV center in diamond can be in several charging states q = 0, q = -l, q = + l. In the framework of this invention uses the state q = - 1.

A single NV center is represented in FIG. 4. Separate NV - the center consists of a nitrogen atom and a vacancy located next to it.

The NV (-) defect has 6 free electrons having a total spin S = 1. The circuit of electronic energy levels for orbitals inside the forbidden zone of diamond is shown in FIG. 5, on the left.

The system of sublevels of the unexcited state is presented in FIG. 5, on the right.

NV - center has optical transitions in the visible and infrared range. The main optical transition is associated with the transition of one electron with e _x, orbitals to ai orbital and is at a wavelength of 637 nm and also has a phonon-broadened spectral tail. After the incoherent excitation of the NV center, it decays into an unexcited state either through an optical transition or through a metastable state that does not preserve the spin value, emitting a photon in the IR range. The probability of making the transition through the metastable state depends on the state of the electron spin of the NV center, being the maximum for the state with spin projection + -1 and the minimum for the spin projection 0. The fluorescence intensity of the NV center in the visible range is thus highly dependent on the spin properties of the center (contrast reaches 30%), which is used for optical reading of the state of the spin system. The metastable state, which changes the spin, has no symmetry to the spin state; therefore, the spin is eventually polarized to the state with the projection 0, realizing the optical spin initialization protocol. The asymmetry of the transitions with respect to the state of the electron spin allows the optical initialization of the electron spin to occur — the incoherent transfer from the + -1 states of the electron spin to the state 0.

Also, the NV-center has allowed dipole transitions in the microwave range. In the unexcited electronic state (both electrons are on the ai sublevel) there is a nonzero spin spin interaction of electrons, which leads to a splitting of the energy level D ~ 2.87 GHz between states with different projection of the electron spin on the NV axis (m _s = 0 and m _s = + / - 1), forming a thin splitting of the ground state. Degeneration by the sign of the projection can be removed by applying a constant magnetic field along the axis of the NV center.

In addition, each of the thin states experiences hyperfine splitting associated with the interaction of the electron spin with the spin of the N _l4 nucleus. Ultra slim

the splitting in the absence of external fields is from 2.8 to 7.2 MHz, depending on the state. The total Hamiltonian for the electronic and nuclear spin systems is written as follows [Philipp Neumann “The nitrogen-vacancy center in diamond”, pp. 42,56-58, 2012]:

H _el = DS ² S _z ² - y _e B _z S _z

H _{ei is the} term in the Hamiltonian corresponding to the interaction of the electron

2

back with a diamond grating field (DS _Z ) and an external magnetic field (- y _e B _z 5 _z ).

D (“2.87 GHz) is the quadrupole splitting of the electron spin-1 in the field of a diamond lattice;

y _e (“2.8 MHz / Gs) is the gyromagnetic ratio of the electron spin; B _{z - the} value of the external magnetic field;

S _{z is the} operator of the projection of the electron spin on the Z axis;

I * addend in the Hamiltonian corresponding to the hyperfine interaction

(H _fi f), the interaction of the nuclear spin with an external magnetic field (H _nZ ), the quadrupole interaction of the nuclear spin (H _Q ).

In turn, the components of the nuclear spin Hamiltonian are written as [Philipp Neumann “The nitrogen-vacancy center in diamond”, pp. 42,56-58, 2012]:

Hnz = -ΎhB · /

H ₀ = QIz

H _{F —} Fermi contact interaction;

\ y _@h \ probability of finding an electron inside the nucleus;

aiso-interaction interaction;

H _{dd is the} dipole-dipole interaction of the electron and nuclear spins;

m _{0 is the} magnetic permeability of vacuum;

Uh ⁼ dp –n ^~ gyromagnetic ratio for the N14 core;

e _{r is the} rth vector ort of the Cartesian coordinate system;

g is the effective distance between the electron and nuclear spins;

B - external magnetic field;

Q is the quadrupole splitting constant for the nuclear spin;

/ nuclear spin vector operator;

5 electron spin vector operator;

The parameters of the Hamiltonian can be found in [Philipp Neumann, “The nitrogen-vacancy center in diamond”, pp. 42,56-58, 2012], [L. I. Childress, “Coherent manipulation of single quantum systems in the solid state,” pp. 25-26 no. March, 2007] [Victor Marcel Acosta “Optical Magnetometry with Nitrogen-Vacancy Centers in Diamond”, p. 15, 2011].

The natural width of the microwave transition line at a frequency of 2.87 GHz is about 100–200 kHz, and the distance between the transitions corresponding to different spin states about 2.1 MHz, thus, in the EPR and O DMR spectra one can observe triplet splitting of states with the projection of the electron spin equal to 0 and 1 (Fig. 6).

However, in the case of using an NV - center ensemble, factors such as voltage in a crystal, impurities Sv and inhomogeneous magnetic field can lead to inhomogeneous broadening of the microwave transition line for different Nn centers from the ensemble, which can lead to deterioration of the gyroscope.

Diamond crystals with a moderate content of NV-defects (1-100 ppm) are best suited for use in the device. Diamonds produced by HPHT without the use of catalysts, CVD with a controlled moderate content of nitrogen impurities, and the absence of other paramagnetic impurities, such as C in, as well as natural diamond crystals can be used. To create an ensemble of Nn-centers in a crystal, it is necessary to conduct irradiation under an electron, proton, neutron, or helium beam, with particle energy exceeding 1 MeV. (ZMEV). After irradiation, it is necessary to hold the sample in a vacuum high-temperature furnace. Annealing mode may be different. As an example, annealing at a temperature of 800 degrees Celsius for 2 hours is used. In the process of annealing, vacancies formed during irradiation become mobile and “find” nitrogen impurity atoms in the diamond lattice.

A diamond crystal can be polished according to a different crystallographic axis. Commercially available plates have [100], [110], [111] orientation. For example, the [100] orientation means that the face of polishing is perpendicular to the edge of the cube of the diamond-faceted lattice. The [111] orientation means that the normal to the polishing plane is parallel to the covalent bond in the diamond lattice (see Fig. 4). For effective interaction of microwave radiation with electron spin, the magnetic alternating field should be directed perpendicular to the axis of the NV center. The most suitable solution would be a microwave resonator shown in FIG. 2, consisting of a printed circuit board (25) on which a capacitor (26) is formed, and two conductive rings (22). The signal to the microwave antenna is fed through the waveguide (27). Microwave resonator must have the necessary degree of adaptability, for use at different frequencies, for example at the transition Ms = -1 -> 0, or Ms = +1 -> 0.

A microstrip antenna (28) is used as the RF antenna, the width of which provides the necessary uniformity of the magnetic field at the RF frequency in the diamond region.

Measurement technology of rotation on the nuclear back of nitrogen

The measurement of rotation is carried out on the basis of the measurement of the parameters of the precession of the total magnetization vector of the nuclear spin of the NV-center ensemble, namely the declination or projection of the vector on the quantization axis, which change in the presence of rotation.

In order to carry out the measurement described above, it is necessary to simultaneously perform an incoherent relaxation initialization of the nuclear spin into states with projection 0 and simultaneous coherent inversion (“drive”) to state 1, or -1, or +1 and -1 simultaneously. The choice of these three cases is due to the type of polarization of the “drive” of the RF. The right circular gives +1, the left circular gives -1, the linear gives both projections. In the process of these effects, it is necessary to measure the projection of the nuclear spin by projecting it onto the state of the electronic spin. This projection is successfully performed during the initialization process, which will be discussed in more detail below. By contrast of fluorescence depending on the state of the electronic spin, the detuning of the “drive” parameters is determined, namely the frequency, and the system is controlled by the feedback method to close the work cycle into a closed loop (close-loop).

Process 1: Relaxation Polarization of Nuclear Spin

Subprocess 1.1

The initialization of the ensemble of nuclear spins of NV centers is carried out in accordance with FIG. 7, FIG. 8. To do this, radiation of an incoherent pumping optical (500-600 nm), coherent resonant UHF1 field at frequencies corresponding to transitions | 0, 1} - | -1, 1} (UHF), | 0, - 1} - 11, - 1} (UHF1) (FIG. 8), radio frequencies at junctions 11, - 1}

-> 11, 0}, | -1,1} - | -1,0} (RF) - the frequencies of these transitions are the same.

The combination of the application of the three types of radiation brings the system into a state with projections of electron and nuclear spin equal to 0, because optical pumping, transferring populations from the Ms = + -1 level to Ms = 0, translates the populations of nuclear sublevels without changes. And as follows from FIG. 8, level | 0,0}, is the only “dark” level from which microwaves do not transfer, therefore, it accumulates population. This method has been studied numerically. FIG. Figure 9 shows the time dependence of the states that started from equally populated thermal populations.

As a result, we have an analog of incoherent pumping for a three-level system — the nuclear spin — of the pumping state from non-zero projections into zero-projection over a characteristic time T _p or at a speed G _p = 1 / T _mit .

Subprocess 1.2 In reality, for a stable initialization operation, it is necessary that shifts in energy levels due to the Zeeman effect (3 MHz / G), or temperature (70 kHz / deg) do not lead to a change in the total spin polarization velocity. For this purpose, a feedback method is implemented using the synchronous detection method. By modulating the frequency of the microwave field in the vicinity of the resonant frequency, it is possible to realize a dispersed circuit, with the linear dependence of the signal necessary for the implementation of the feedback on the distance to the desired frequency, using the synchronous detection circuit shown in FIG. ten.

Process 2. Drive the nuclear spin in the ground state of the electron spin.

By virtue of the implementation of the process 1 - “initialization”, the nuclear spin relaxes to the state gsch = 0 - i.e. to the "Equator" of the scope of possible positions of the back (not the scope of the Bloch). As a result of this relaxation, the nuclear spin gradually loses the phase and projection that it had.

In contrast to initialization, “drive” is necessary for a flip from the zero projection to 1 (-1, or both). This process, together with decoherence, leads to the fact that the populations of nuclear states come to equilibrium, which can be determined from a system of kinetic equations:

dN (, 1, -1) = Г mi, N _h (1, -1) + WD _h ri .ve N _h

dt

dN,

- ° = G _M (N, + N _,) - h _aL .N „

dt

Where G is the initialization speed, W is the frequency of the Rabi drive field.

Whence for the case when pumping is carried out immediately on +1 and -1 projections

Where a = w / g

As can be seen, with a constant initialization rate G, population, and therefore, the level of fluorescence depends on the detuning of the RF drive frequency.

Rotation triggers extra fluorescence level drift (see below). Leaving the level of fluorescence due to rotation can be compensated by RF detuning. The detuning required to compensate will unambiguously characterize the amount of rotation. In this case, since the effect of rotation will be compensated, the operating point will remain unchanged. To do this, however, the system must be derived from the maximum or minimum of fluorescence in which the response of the system is quadratic in deflection effects.

To bring the system into a sensitive state, it is necessary to set the system on the slope of the resonant circuit in the absence of rotation. The choice of the working point of the gyroscope according to the parameters G, D, and - determines the sensitivity of the signal to rotation. The optimum sensitivity position corresponds to D = ± W / L / 3. Then the frequency changes of Rabi with resonance detuning will be equal

Leading to sensitivity in the population

dN _{± l} 6N _{± i} 6W PLN / З

dA yes GdA 8G (1 + 2a †

Process 3. Measuring the state of the nuclear spin by projecting it onto the electron spin and measuring rotation

When making a spin, the spin system continues to precess in space, while the antenna, and with it the radio frequency field, begins to rotate, gaining phase with respect to the rotating spin. A linear change in phase with time is a change in frequency. The appearance of this additional frequency will change the precession frequency, which will lead to a change in the level of the fluorescence signal as described above. A feedback loop (45-50 fig. 3), in which the control action is the detuning of the RF generator, and the controlled value — the fluorescence value of the NV-center ensemble compensates for this change. In this case, the compensation feedback signal will be a measure of the change in the precession frequency. Thus, due to feedback compensation, the instrument's operating point is almost not shifted until changes in the rotational speed are slower than the speed of the feedback loop, and the detuning of the RF generator frequency is linearly proportional to the angular velocity of rotation.

In the scheme of continuous measurement, three simultaneous modulations of frequencies occur (RF1 ~ 5 MHz). The frequencies of the microwave, for which there is a minimum of fluorescence, and RF, for which there is a maximum of fluorescence, represent a linear combination of external parameters: magnetic field, temperature and angular velocity of rotation. The position of the extremes is determined by sinusoidal or meandering modulation of parameters, followed by synchronous demodulation 1 harmonics of the received signal and regulation of the parameter bias in the feedback loop. Details of the work of this method can be, for example, found in [Arie et al., Opt. Lett. 17, 1204.1992].

However, to bind simultaneously in 3 parameters, it is necessary to spread the modulation frequencies, on the one hand, so that the beats between the individual modulation frequencies do not fall into the frequency domain of demodulation, on the other hand, do not exceed the system response speed. To increase the accuracy due to the inertia of the temperature, the microwave frequencies are represented as F _MWI ⁼ F _MWO ^~ ^ _{MW »} Dhci / 2 ⁼ Dhci / o + ^ _MW - The frequency F _MW0 is linearly related to the temperature of the sensor, while A _MW mainly tied to the projection of the external magnetic field. This allows slow modulation of F _MW0 and fast modulation A _{mi /.} The error signal of slow modulation is not of interest to calculate the angular velocity.

The third RF modulation occurs at an intermediate frequency (between modulation frequencies A _MW and F _MW0 ). The RF1 S _RF error signal contains the angular velocity of rotation, from which the angular velocity of rotation is obtained by subtracting the nuclear quadrupole splitting.

As mentioned above, with constant operation, the frequencies of RF1, RF2, UHF1, UHF2 are modulated. Sources of modulations are the generators of a sinusoidal signal (32,43,47, Fig. 3). The modulation signals are summed with the feedback signals from the proportional-integral-differential controllers (33,44,46) on the adders (34,35,45). The resulting control signals using the adder (36) and subtractors (37.40) form the control signals for the microwave generators (38), microwave frequencies (39), RF1 (42), RF2 (41). These signals change the frequencies of the oscillators, allowing you to scan the resonant lines at the frequencies described in the “Process 1” section.

When modulating frequencies, the fluorescence signal (51) contains all the components of the signal offset from the resonant frequencies, spectrally transferred to the modulation frequency. The component data is demodulated by spectral filtering at the modulation frequency using band-pass filters (29.49.52), followed by multiplying (30.48.53) the signal by the modulation signal from the generators (32.43.47), the phase of which is compensated to take into account the inevitable response delay of the system subject to modulation, delay lines (31,50,54). Demodulated frequency offset signals are applied to the proportional-integral differential controllers (33,44,46), closing the feedback loop binding to the resonant lines.

The application of the developed technical solution allows to obtain the following technical indicators.

Reducing the volume of the sensitive element of the sensor: less than 1 cu. cm.

High specific spectral sensitivity of the element: 0.3 x 10-3 GD. / l / hour

Low drift sensitivity: ~ 10-3 GD. /hour

The possibility of creating a hybrid device that includes a sensor measuring three physical parameters (3x axial gyroscope, magnetometer, temperature sensor).

Claims

CLAIM

1. The method of measuring rotation in space using a rotation sensor containing a diamond plate with color centers, including the following steps,

- calibrate the sensor by transferring the system of electronic spins of color centers to the state with m _s = 0 with the projection of electronic spins on the axis NV of the center equal to zero due to the constant impact on the diamond plate of the incoherent optical field, as well as the transfer of a part of the system of electronic spins corresponding to the projection of the nuclear spin nc = 1 hsch = -1, color centers from the state m _s = 0 to the state m _s = (+/-) 1 and ns = (- / +) 1 with the projection of the indicated spins on the axis NV of the center equal to plus one | 0, 1 } -> · | - 1, 1} and minus one | 0, - 1} -> · | 1, -1} due to constant and simultaneous The exposure of the diamond plate to optical incoherent radiation, two-frequency microwave radiation (microwave) and magnetic field, after which they transfer the systems of nuclear spins to the state nc = 0 due to the constant action on the diamond plate of radio frequency radiation (RF), which realizes the transitions | 1, - 1} <- "· 11,0}, | -1, 1} <-" · | - 1,0},

- bring the sensor into a state sensitive to rotation due to the application to the system of a nuclear spin, which is in the state m _s = 0, gsch = 0, of resonant radio frequency radiation,

- minimize the measurement error of rotation of the modulated microwave frequencies in the vicinity of two resonant frequencies corresponding to different values of the electronic spin, while registering the response of the electronic spin on the fluorescence signal of the diamond plate at modulation frequencies and produce a correction frequency of the microwave signal based on the measured error signal returning the radiation frequency to the maxima of the resonant circuits,

- calculate with a given periodicity the angular velocity of rotation of the sensor as the difference is constantly monitored frequency of radio frequency radiation, and the known value of quadrupole splitting of the nuclear spin, while continuously adjusting the frequency of radio frequency radiation due to modulation of the frequency of radio frequency radiation in the vicinity of the resonant frequency of the nuclear spin, while registering the response nuclear spin on the fluorescence signal of the diamond plate at the modulation frequency and produce a corrective part from the signal based on the measured error signal that returns the frequency of the radiation to the maximum of the resonant circuit.

2. The method according to p. 1, characterized in that they provide with the help of an optical system for directing radiation to the diamond plate the pump power density on the diamond plate is not less than 10 W / mm2.

3. The method according to p. 2, characterized in that they create a magnetic field on the diamond plate up to 20 Gauss.

4. The method according to p. 3, characterized in that they provide with a microwave antenna electromagnetic field on a diamond plate with a uniformity of more than 90%.

5. The method according to p. 4, characterized in that using optical provide the efficiency of collecting fluorescence emission of at least 10%.

6. The rotation sensor on the color centers, containing

- diamond plate with color centers,

- a source of incoherent light with an optical system for directing radiation to a diamond plate, providing a pump power density sufficient to convert the system of electron spins of color centers to the state | 0, 1} with the projection of these spins on the axis NV of the center equal to zero due to the constant impact on the diamond plate incoherent optical field

- two sources of microwave radiation (microwave), modulated in amplitude and frequency, and a source of constant magnetic field to convert part of the system of electronic spins of color centers to the state with the projection of these spins on oc _b NV center equal to one | 0, 1} | - 1 , 1} and minus one | 0, - 1} | 1, -1} due to the constant and simultaneous impact on the diamond plate of the dual frequency microwave and magnetic field, while the source of the magnetic field is part of the antenna to create a microwave and is located in such a way that creates a magnetic field in the direction most orthogonal to the orientation of the crystallographic axis, or In the case of a three-axis variant, a magnetic field is created in the direction not collinear 3m to the axes,

- two sources of radiofrequency radiation to align the system of nuclear spins into a state sensitive to rotation in the sensor space due to the constant effect of RF radiation on the diamond plate, which realizes the transitions | 1, -1} <-> · 11.0}, | -1, 1} <-> · | -1,0},

- a photodetector for detecting the fluorescence of color centers in the diamond plate, as well as an optical system that allows you to direct the fluorescence from the diamond plate to the photodetector,

- a controller that, by means of control signals, generates feedback through constant microwave modulation in the vicinity of 2 resonant frequencies at based on the magnitude of the electron spin response through fluorescence registration at the modulation frequency, as well as constant RF modulation in the vicinity of the resonance frequency of the nuclear spin based on the nuclear spin response value through fluorescence registration at the modulation frequency, and calculates the angular rotational speed as the difference of the constantly monitored frequency of radio frequency radiation, and the known value of quadrupole splitting of the nuclear spin.

7. Sensor and. 6, characterized in that a source of incoherent radiation with a spectrum in the range from 500 nm to 580 nm is used, the optical power at the output of the source is at least 0.1 W.

8. The sensor according to claim 7, characterized in that an antenna is used for a microwave with a frequency range from 2.6 to 3 GHz.

9. The sensor according to claim 8, characterized in that a source of a constant magnetic field is used, which allows creating a field on a diamond plate up to 20 Gauss and having a temperature stability of more than 1 Gauss per hour.

10. The sensor according to claim 9, characterized in that it includes RF radiation sources operating in the range up to 10 MHz.

11. Sensor for and. 10, characterized in that a photodetector operating in the spectral range from 600 to 800 nm, having a frequency band of more than 1 MHz and providing a signal-to-noise ratio at the output of at least 50 dB, is used,

12. Sensor for and. 11, characterized in that the magnitude of the projection of the magnetic field on the perpendicular to the selected axes of the crystal is at least 0.3 Gs.

13. Sensor for and. 12, characterized in that the quadrupole splitting of the nuclear spin, equal to 4.95 MHz, is used.