Quantum Correlations And Realizing Quantum Dense Coding Based On The Single Jaynes- Cummings Atom And An Isolated Atom System

Quantum information science is a new interdiscipline which is a combination of quantum mechanics and information science.As a core of quantum information,quantum entanglement provides an important physical resource for realization of quantum communication and quantum computation and is widely used in quantum information processing,such as quantum dense coding,quantum teleportation,quantum error correction,quantum cryptography and so on.It has been discovered that quantum entanglement can't measure entire correlations of non-locality of quantum system.Recently, it was found that there are some quantum correlations other than entanglement that also offer some advantage, such as such as quantum discord and geometric quantum discord. In general, this correlation is different from entanglement, and quantum discord may be nonzero even for certain separable states. So,it's significant for developing quantum information science.In this paper, the contents of research include the following aspects:(1)Various correlations in the system of single Jaynes-Cummings(J-C)atom and an isolated atom are studied via the measurement of geometric quantum discord proposed by Dakic et al. The dynamical evolutions of geometric quantum discord between two atoms are numerically analyzed as well as those of the quantum entanglement and quantum discord.Results show that quantum correlations can be increased by increasing initial entanglement and purity of the prepared W-state of the two atoms. The coupling constant and photon number may also play a significant role in the quantum correlation dynamics.(2)This paper mainly studies quantum dense coding via a model of single J-C two-level atom A plus an isolated atom B. The effects of the initial Werner-like state purity,initial entanglement and photon number on the channel capacity of dense coding are discussed.The results show that channel capacity can be increased by increasing the initial purity and entanglement. Particularly,optimal dense coding can be realized when the photon number is zero. For then on zero photon number, the channel capacity exhibits a damping oscillation.(3)Using double Jaynes-Cummings coupling model in the two-level atoms of two entangled atoms as quantum teleportation channel,studied the realization of quantum teleportation.The effects of the initial Werner-like state purity, initial entanglement and photon number on the fidelity of quantum teleportation are discussed.The results show that fidelity can be increased by increasing the initialpurity and entanglement and this time can always realization of quantum teleportation.In addition also found, Fidelity of average photon number directly affects the frequency and damping oscillation in the process of evolution.