The Generation Of Steady-state Spin Squeezing In NV Centers System

In recent years,spin squeezing has attracted scientists'attention.Compared with the optical squeezed state,the spin squeezed state is easier to store,and physicists found that the degree of squeezing produced in the spin system can be greater,so the spin squeezing has attracted great attention.As a kind of multi-body entanglement source,spin compression can exceed the standard quantum limit to improve the signal-to-noise ratio and achieve accurate measurement.At the same time,spin compression can be used to improve the stability of atomic clocks,magnetic sensors and other measurements based on the principle of atomic interference.In this paper,we mainly study the generation of steady-state spin squeezing in the coupling system of nanotubes and NV centers?N-itrogen-Vacancy center?.In recent years,great efforts have been made in the solid-state system operation of electron spin related to NV centers.These work provide a new way to explore the basic concepts of quantum physics and the possible applications of quantum information and computation.It is easy to control and read the NV self spin by using the magnetic and optical fields,and the ground state has a very long coherent time at room temperature.In addition,NV centers has advantages in the storage and transmission of quantum information.These diverse characteristics and advantages make NV centers a system with great research value of quantum technology,including quantum information processing and sensing applications.This paper is divided into three parts:The first part is the first two chapters.The first chapter mainly introduces the development and research background of spin compression.In the second chapter,the theory and basic concepts of spin compression are introduced in detail.It mainly includes the definition of spin squeezing and the description of several spin squeezing parameters,the spin squeezing parameters of odd and even states,the relationship between spin squeezing and dual correlation and quantum entanglement,the spin squeezing inequality of high spin system and the self selected squeezing in NV color center system.The second part is the third chapter,which mainly introduces the theoretical basis and research tools related to the system.There are three kinds of quantum mechanics picture and quantum master equation.The third part is the main part of this thesis.The hybrid quantum system with NV color center can be used to prepare the long phase dry time of spin and the strong coupling of subsystems.Recently,it has aroused the interest of quantum simulation,especially in the coupling of NV spin and mechanical resonance in diamond crystal.Recently,different schemes have been proposed for spin compression in NV centers system.Bennett et al^[112].Developed a scheme to generate spin compression in diamond mechanical nano resonators.Inspired by this model,we study the spin squeezing evolution of a hybrid quantum system consisting of a spin ensemble driven by a single-mode radiation field and nanotubes.According to the model,the corresponding Hamiltonian is written and sorted into the form of effective Hamiltonian.On the basis of the derived main equation,the spin compression evolution behavior of the system is simulated.The effects of different effective Rabi frequency,dissipation rate,the number of equilibrium phonons and the number of spin squeezing on spin squeezing are analyzed.The results show that the steady-state spin compression can be produced by using the external magnetic field.The fifth chapter is the summary and Prospect of this paper.