The Study Of Quantum Correlation And Dense Coding In A Two-qubit Spin Squeezing System

Quantum correlation and dense coding has been extensively investigated in recent years, because it is one of the most fascinating features of quantum mechanics and plays an important role in quantum information processing(QIP) and quantum computation fields. Inspired by previous investigations, in this paper we studied the quantum correlation and dense coding in two-qubit spin squeezing system are investigated.The general situation, current research status and prospects of quantum information science is introduced firstly. In Chapter 2, we give out the definition of three quantum correlation measurements.In chapter 3, using the concurrence(C) criterion, we investigate the thermal entanglement properties in two-qubit spin squeezing model for two kinds of squeezing interaction: one-axis twisting model(OATM) and two-axis countertwisting model(TACM) with a transverse field. We study the thermal entanglement properties for two temperature cases: limit temperature and finite temperature respectively in each model. In chapter 4, using the C and QD criterions, the quantum correlation properties in two qubitsone-axis spin squeezing model with an external magnetic field are investigated. It is found that one obvious difference at ground state is the sudden disappearance phenomenon(SDP) occured in the behaviors of C, while not in QD. And for the finite temperature case,one evident difference is that the sudden birth phenomenon(SBP) is appeared in the evolution of C, while not in QD. In chapter 5, we investigate the effects of spin squeezing interaction, external magnetic field and temperature on dense coding properties in two-qubit spin squeezing model for two kinds of squeezing interaction: one-axis twisting model(OATM) and two-axis countertwisting model(TACM) with a transverse field. We found that it is hard to valid dense coding when the system in OATM and it is easy to carry out valid dense coding and optimal dense coding when the system in TACM. Finaly, the conclusion is give out.