Research On The Phonon-Assisted Spin Quantum State Detection Method Applied To The NV Center Gyroscope

As a novel gyroscope combining quantum physics,quantum materials,quantum optics and micro-nano technology,the NV center solid state spin gyroscope has comprehensive advantages such as high sensitivity,predominant environmental adaptability and potential of small size.It has potential application value in military application fields such as aviation,aerospace and guidance.It also has potential application value in civil fields such as geodetic surveying,geological exploration,tunnel engineering,petroleum exploration,mining and marine development.It takes the demand for new quantum gyroscopes in future potential application as the starting point,and takes the NV center quantum gyroscope as the research object in this paper.We carried out research on the phonon-assisted spin quantum state detection method applied to the NV center gyroscope,researching key technologies such as the phonon-assisted detection mechanism and phonon-assisted solid state spin angular velocity measurement method of the NV center,providing theoretical and technical support for promoting this kind of quantum gyroscope from theoretical verification to application.The main research work of this paper is as follows:(1)The structural properties,spin properties and optical polarization readout properties of the NV center are analyzed.The decoherence mechanism of the electron spins and the optical transition dynamics of the NV center is analyzed through the two-level and three-level model.The solid-state spin manipulation and measurement technology of the NV center are studied,which provide theoretical support for the research on the phonon-assisted spin quantum state detection method applied to the NV center gyroscope.(2)Angular velocity measurement model construction and sensitivity evaluation of the optical detection magnetic resonance of the NV center.The principle and coherent manipulation timing characteristics of the quantum cumulative phase angular velocity measurement of the NV center are analyzed.On this basis,an optical detection magnetic resonance angular velocity measurement method of the NV center is studied,and corresponding model was constructed.The sensitivity of this method is compared to the quantum cumulative phase angular velocity measurement method.Research results show that the theoretical sensitivity of non-nitrogen-coupled quantum accumulation phase angular velocity measurement method is 1.09×10-3 °/(?)for the hypothetical parameters in this paper.When the decoherence time T2*is 1000 μs,and concentration of the NV center concentration is 1×1018/cm3,the sensitivity of the nitrogen-coupled quantum cumulative phase angular velocity measurement method is up to 1.01 ×10-5 °/(?)theoretically.The sensitivity of optical detection magnetic resonance angular velocity measurement of the NV center is related to magnetic field intensity,and the angle between the NV center axis and the direction of the magnetic field at different rotating times.The average sensitivity of the optical detection magnetic resonance angular velocity measurement method is 9×106 °/(?)when the external uniform magnetic field is 100 G.(3)Phonon-assisted detection mechanism for the angular velocity measurement of the NV center.The strain-induced energy transferable phonon-spin interaction coupling excitation model was established based on the relationship between the wave function and the lattice displacement vector.The coefficient matrix satisfying Bloch’s theorem was introduced to establish the phonon spectrum models of the first Brillouin zone characteristic region for different axial NV centers in this paper.The phonon thermal balance properties of the phonon-assisted detection system are analyzed.The structure optimization model of different axial NV centers for the phonon model was constructed based on the molecular dynamic simulation software CASTEP and density functional theory for the first-principles research.Its structural characteristics,phonon characteristics,and thermodynamic properties were analyzed.The research results show that the phonon mode’s evolution depends on the occupation of the NV center.A decrease in thermodynamic entropy accompanies the strengthening of the phonon mode.The phonon main resonance frequency of the NV center diamond is in the order of THz,and the sub-resonance frequency is in the order of hundreds of MHz.The phonon-assisted detection device for the NV center is designed according to this frequency band can effectively increase the spin transition probability of the NV center,improving the sensitivity of the angular velocity measurement.(4)Design and fabrication of the piezoelectric phonon-assisted device of the NV center.The structure of the piezoelectric phonon-assisted device of the NV center including interdigital electrode layer,ZnO piezoelectric thin membrane layer and diamond substrate containing the NV center was designed based on the phonon-assisted detection mechanism of the NV center.The phonon field characteristic function of the piezoelectric phonon-assisted device the NV center is established according to the Bragg reflection equation under the condition of small periodic perturbation.The differential equation of phonon transfer for the NV center piezoelectric phonon-assisted device is established combined with the spatial gradient field equation of the phonon-assisted device.The effect of crystal orientation and membrane thickness of ZnO piezoelectric membrane on the phase velocity v and the electromechanical coupling coefficient K2 of the NV center piezoelectric phonon-assisted device are mainly studied based on the finite element software COMSOL.The structure of the NV center piezoelectric phonon-assisted device is optimized and MEMS prepared.The results show that piezoelectric phonon-assisted device of the NV center has optimized performance for the thickness of the(100)ZnO piezoelectric membrane of 400 nm,the IDT layer located between the ZnO piezoelectric membrane and the diamond,with its thickness of 100 nm under the simulation parameters condition in this paper.(5)Experimental verification of the angular velocity measurement principle and the phonon-assisted spin quantum state detection method of the NV center.Angular velocity measurement module of the NV center was built under the reciprocating swing condition.The quantum gyroscope effect of the NV center is studied when the slider moves down(the NV center rotates counterclockwise).Also,the optical detection magnetic resonance angular velocity measurement experiment was carried out based on the optical detection magnetic resonance angular velocity measurement module built in this paper.Experimental results show that the sensitivities of the quantum cumulative phase angular velocity measurement of the single NV center for non-nitrogen-coupled and 14N-coupled are 3.897 × 10-4 quantum cumulative phase°/(°/s)and 3.117 × 10-3 quantum cumulative phase°/(°/s),respectively.The measurement error of the optical detection magnetic resonance angular velocity under the experimental conditions of this paper is less than 20%,which verifying the principle of angular velocity measurement of the NV center.The phonon-assisted detection experiment is carried out based on the piezoelectric phonon-assisted device of the NV center.Experimental results show that the the transition efficiency of the phonon-assisted detection method with the phonon excitation frequency of 350 MHz is improved by 1.29%.The sensitivity of the angular velocity measurement of the single NV center is 8.44%higher than that of nonphonon-assisted case,which verifying the phonon-assisted spin quantum state detection method of the NV center.