Research On Quantum Properties Of Nanodiamond Nitrogen Vacancy Center System And Single-Photon Microwave Resonator System

Quantum mechanics is the basic theory of studying the microscopic world,which promotes the research and development of many technical fields.Quantum entanglement is the main physical quantity of quantum mechanics that is different from classical mechanics.It is also an important research content in modern quantum informatics research.It plays a very important role in quantum teleportation,quantum communication,long-range quantum computing and quantum high-precision measurement.Among many quantum systems,mechanical vibrators have better frequency adjustability and higher quality factors,which can be used to study quantum properties such as quantum entanglement and quantum superposition state.And with the development of nanotechnology,nanometer mechanical vibrator is used in quantum experimental research.This thesis studies the preparation and parameter regulation of quantum states in nanodiamond-nitrogen vacancy center system and single-photon microwave resonator system,and the evolutionary properties of entanglement in quantum systems composed of mechanical oscillator and microscopic particle or cavity field,as well as quantum state transfer,etc..The specific content is as follows:The evolution properties of quantum entanglement in the second-order magnetic gradient induced nano-diamond mechanical oscillator coupled to nitrogen vacancy center system are studied.The influence of different factors on the entanglement properties of the mechanical oscillator’s dual-mode coupled to nitrogen vacancy center is discussed according to the negativity.The attenuation factor of the mechanical vibrator,the spontaneous radiance of the center of the nitrogen vacancy,the initial state of the system corresponding to different coherence angles,and the coupling strength is included.The evolutionary properties of entanglement between three bodies in the system are analyzed.It is found that the anti-attenuation ability of the entanglement can be controlled by the coherence angle of the system.And when the initial states of the three bodies are pure state,the maximum entangled state of the tripartite is obtained.The quantum properties of the single-photon emitter and mechanical vibrator coupled to microwave field system are studied.The evolution of the bipartite entanglement is discussed through the negativity in the quantum system that consist of the single-photon emitter,the membrane vibration mode and the microwave mode.Therefore,the quantum state transfer and the required conditions of the single-photon emitter and microwave field photon are analyzed after adiabatic elimination of vibration mode.It is found that quantum state transfer between optical photon and microwave photon can be achieved by manipulating the coupling strength and the coherence angle of the single-photon emitter.And the evolution of the bipartite entanglement in the system is affected by the coherence angle and the coupling strengths.