Quantum Information Processing Based On The Diamond Spin Ensemble Hybrid System Via Strain Modulation

Quantum information science is a new-frontier-crossed discipline focusing on information calculation,encoding and transfer via the entanglement and coherence properties of the quantum system.It combines quantum mechanics,information science and computing science.Both theoretical and experimental research on quantum information have obtained rapid development,and lots of progress has been made in recent years.To date,many physical systems can be used to realize quantum information processing,such as cavity quantum electrodynamics,ion trap,nuclear magnetic resonance,superconducting Josephson junction,quantum dot,diamond nitrogen-vacancy center(NVC).Among these physical systems,cavity quantum electrodynamics,ion trap and nuclear magnetic resonance might be mature,but not fit for large-scale quantum information processing.Although superconducting Josephson junction,quantum dot and NVC are advantageous for the scalable quantum information processing,they developed slowly due to the limit of decoherence.At present,the more practical quantum information processing devices might be the hybrid system consisting of multiple quantum systems.It gathers the merits of different subsystems simultaneously,and avoid their own physical limits.Additionally,NVC system possesses many distinct advantages.For example,the electronic spin of the NVC has long coherent time at room temperature.It can simultaneously couple with many external fields,such as magnetic field,microwave field and optical field,and be precisely manipulated.Therefore,NVC can interact with many other quantum systems(such as mechanical resonator and superconducting cavity),which forms the hybrid system.With the development of the nanofabrication technology and improvement of the experimental condition,NVC hybrid system has been regarded as one of the most effective system to implement large-scale quantum information processing at present.In this article,we mainly study the basic issue in quantum information processing and nonlinear acoustics based on NVC hybrid system,including the generation and entanglement dynamics of macroscopic nonclassical state and electromagnetically induced acoustic wave transparency phenomenon.In chapter one,we briefly introduce the investigation history of quantum information science,including the theoretical and experimental research in the field of quantum computing,quantum communication and quantum simulation.In chapter two,we briefly introduce some related theoretical and experimental background of diamond NVC and electromagnetically induced transparency.From chapter three to chapter five,we introduce our research work.The research contents include the following three parts:1.We propose a theoretical scheme to realize electromagnetically induced acoustic wave transparency(EIAT)in a diamond mechanical resonator(DMR)system by utilizing the dynamical strain-mediated coupling mechanism.EIAT means that the system becomes transparent to the acoustic field in some certain parameters.It is found that single and three multiple EIAT windows occur in the lambda-type and delta-type transition structure in the subspace spanned by the ground states of the NVC,which is formed by the joint action of the microwave fields and strain field.Besides,the switching between single and three EIAT windows can be obtained by properly adjusting the system parameters.Based on our new ideas,this hybrid system could be used to construct a "slow sound" solid-state physical materials.It could also promote phonon-based quantum information processing applications on the NVC hybrid system.2.We propose a specific scheme to achieve macroscopic mechanical Schrodinger cat state(SCS)in the DMR system via the dynamical strain coupling mechanism.In our model,the direct coupling between NVC and lattice strain field can be used to achieve spin and phonon interaction in the quantum regime.We construct a cyclic delta-type transition structure of NVC ground state subspace by means of the joint driving of the phonon strain field and a pair of external microwave fields.Besides,we realize the population transfer between different energy levels of NVC system by properly adjusting the system parameters.Based on this physical process,the macroscopic SCS of the DMR was obtained.Additionally,we demonstrate the different features of the nonclassicality of the SCS in dissipative case and non-dissipative case.Our work provides a new route for realizing the large-scale quantum computing and quantum information processing based on the DMR system.3.We propose a theoretical scheme to realize macroscopic entanglement between two separate NVC spin ensemble(NVE)based on the hybrid system,which consists of NVE and superconducting coplanar waveguide resonator(CPWR).It is found that,the excitation initially prepared in the CPWR can be transferred between the NVE and CPWR,and finally distributed in these two NVEs.The entanglement between two NVEs is generated in this process.Besides,the higher amount of entanglement between NVEs can be generated in our model even when the dissipation of the NVEs and CPWR are considered.Our scheme is scalable,which means it can be used to entangle multiple NVEs.It has certain significance to realize the solid-state quantum network.The last chapter presents a summary of this dissertation,and then gives some outlook for the investigation.