Generation Of Entangled States And Information Concentration In Cavity QED

The quantum information science is the combination of quantum mechanics and the information theory, which is formalized in the 1980s, and it can solve many information processing problems which cannot be achieved with the classical information theory. It is rapidly growing brand-new cross science subject with a wide and profound future application field since then. In the field of quantum information, cavity quantum electrodynamics(C-QED)is considered to be one of the most prospective physical systems to realize quantum information processing and quantum computer. We can achieve the conversion between atomic quantum bit and photon quantum bit using it. Then we can fulfill the process of the quantum information. In this paper, the generation of entangled states and information concentration in cavity QED are studied, and many significant results have been obtained.In chapter 1, at first, a simple overview is presented for the bring history background of quantum entanglement, then the basic theories of quantum entanglement are explicated. Especially, the definition of quantum entanglement, a few kinds of familiar entangled states, the measurement of the degree of quantum entanglement, and the physical implementation of manipulation of quantum entanglement, which form the theoretical basic of the works in the following chapters, are discussed in detail.In chapter 2, the basic theories of cavity quantum electrodynamics system are elaborated, especially for technology of generating of entangled states and realizing the process of quantum teleportation, which lay the foundation for the study of generation of maximal entangled states via entanglement swapping and realization of remote atomic information concentration in cavity QED.In chapter 3, the generation of maximally entangled states via entanglement swappingin cavity QED is studied. Using techniques of entanglement swapping, we can create the maximally entangled photon-photon states as well as the maximally entangled atom-photon states from the same initial states in cavity QED. The preparation of the initial pairs of entangled states in our scheme is relatively simple. Our scheme also does not require the measurement in Bell basis. These advantages can warrant the current schememore feasible in experiments.%â– In chapter 4, the realization of remote atomic information concentration in cavity QED is investigated. We propose a scheme for information concentration of two ,, three remote two-level atoms in cavity QED. The idea can directly be generalized in the case of multi-atom information concentration. Our scheme does not involve the Bell-state measurement. Moreover, during the interaction between atom and cavity, the cavity frequency is large detuned from the atomic transition frequency, thus the scheme is insensitive to both the cavity decay and the thermal field. We note that the idea can also be applied to the ion trap system.