| 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 teleportation, quantum dense coding, quantum cryptography, quantum error correction and so on. To realize quantum information processing, quantum hardware is essential. The cavity QED technology is considered one of the most promising physical systems that people put forward to carry out quantum information processing and quantum computation.This thesis focuses on preparation of two special multi-particle entanglement, NOON state and singlet state. NOON state is a kind of maximally entangled state that can be used to demonstrate multi-photon de Broglie wavelength and can be applied to the quantum phase measurement. Singlet state is a special type of entangled state with total spin zero. This thesis mainly carries out the following researches:1. We present a scheme to generate a NOON state in the atom-cavity system. An atom is embedded in a two-mode cavity, then we make use of the hyperfine structure of the atom to realize the interaction between special atom energy levels and cavity field. With the assistant of external classical fields, we can realize the entanglement between atom energy levels and photon number state. At last, we get the NOON states via a single-qubit operation.2. We propose a scheme to generate a three-qubit three-level singlet state in cavity QED, by placing three∧-type SQUIDs in a single mode cavity. In this scheme, we make use of the interaction between the SQUIDs and cavity filed, and the classical pulses. The cavity fields are in vacuum state during the whole operation processes of creating the entanglement, and there is no quantum information transfer between the SQUIDs and cavity fields. |
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