Quantum Manipulation And Simulation In Photonic Systems

The use of quantum physics has revolutionized the way we communicate and process information.Quantum coherence and decoherence are at the heart of both foundations and applications of quantum physics.When there is no decoherence,any physical system should offer the possibility to implement a large number of quantum gates and transfer information.A photon is an element particle of electromagnetic radiation with a well-defined energy,due to its high speed,strong stability and low dissipation,photon has been an ideal carrier of quantum information as well as the experimental implementation of quantum information processing.The current explosion in information technology has been derived from our ability to control the flow of photons in the most intricate ways,specially,the experiment on slow light.This dissertation theoretical study on the following two problems:one is on how to control the flow of photons by means of the atomic ensemble system,which includes the propagation of slow light in a rectangle atomic medium and the scattering process of photons confined in a one dimensional optical waveguide.The other is on simulation the quantum information processing in optical system,which includes realizing error-free discriminations of quantum states and the quantum game of the two-player quantum prisoner's dilemma by using linear optical elements.This dissertation includes five part.It is organized as follows:The first part is introduction,which paves the way for the dissertation. In this part,we introduce the history of the development of the quantum information and quantum computation,as well as its status of current research.The second part is the second chapter of this dissertation.Here we mainly concerns on how to coherently control the propagation of slow light by a rectangle atomic medium.Currently there are two ways to get the slow light:coher- ent population oscillation and electromagnetical induced transparency.First, we theoretically predicted a phenomenon of the enhanced light deflection by an atomic ensemble through coherent population oscillation mechanism,which is realized by a two-level atomic ensemble interacting with a control field and a much weaker probe field.Here both optical fields are treated classical.Then, for the light deflection by a A-type atomic ensemble,we systematically develop a quantum theory describing the spatial motion of polaritons in inhomogeneous magnetic fields.Our treatment is based on the mean field theory.The third part is the third chapter of this dissertation.Here,we study the coherent transport of photons,which propagate in a one-dimensional coupled-resonator waveguide(CRW) and are scattered by an atomic ensemble localized in one of the CRW.The coherent control can be realized by adjusting the detuning between the single photon frequency and the energylevel-spacings of the atoms.There also exist bound states which trap the single photon in the CRW.The forth part is the forth chapter of this dissertation.We propose a linear optical scheme for optimal unambiguous discrimination among nonorthogonal quantum states,and also simulation the quantum game of the two-player quantum prisoner's dilemma.Here,both spatial anb polarization degree of freedom of single photon are used.A summary of the work and an outlook of this thesis are given in the last part.