Investigation On Preparation Of Optical Quantum States Via Conditional Measurement And Quantum Communication Networks

In the last two decades, systems of quantum optics are progressively emerging as an important physical ground for the study and the experimental realization of quantum communication, quantum computation and quantum information processes. The basic principles of quantum mechanics, the quantum superposition principle and the Heisenberg uncertainty principle, lead to the existence of nonfactorizable dynamics and thus physically nonseparable quantum states. The nonseparable states in quantum mechanics are named entangled states, which have the peculiar structure of the nonlocal correlations. The quantum entanglement can be regarded as true physical resources for the development of quantum information science. The optical quantum states can serve as the information carriers and also are easily manipulated with the schemes of quantum optics to realize information processes. The engineering of optical quantum states implements the preparation, transformation and manipulation of quantum states of light by means of physical methods.In the thesis, the fundamental physics for the quantum information science, quantum mechanics and quantum optics, is briefly summarized at first(Chapter 2) after the introduction(Chapter 1); In Chapter 3, a physical scheme for the simultaneously generating radiation-field modes of a single photon state and a superposition state of zero- and one-photon is proposed; In Chapter 4, the generation systems of multipartite entangled states for continuous variables utilizing the squeezed states of light and linearly optical transformation are discussed, the experimentally measurable criterion inequalities for checking the multipartite entanglement of continuous variables are given, and a few of quantum communication networks are introduced; The conclusion and prospection are presented in Chapter 5. The completed creative works are as following:1. We theoretically demonstrated that a single-photon state and a zero-and one-photon superposition state can be simultaneously prepared via the conditional measurement of a two-mode squeezed state.2. An experimental system realizing above proposal is designed, in which the nondegenerate optical parametric amplifiers are used for the basic devices.