Investigation Of Quantum Properties And Quantum Measurement Of Optical Parametric Process

Quantum information has been developed rapidly over the past twenty years.In the field of quantum information,the non-classical fields such as squeezed vacuum state,quantum correlation twin beams,EPR entangle state, squeezed amplitude state and so on have been proved to be important in quantum measurement and quantum communication.It has the wide application in quantum teleportation,quantum non-demolition measurement, quantum dense coding and quantum entanglement swap etc.According to the eigenstates of applied quantum systems with discrete or continuous spectrum construction,the quantum information is divided into two types:discrete variables(dv) and continuous variables(cv).They have different features and application potentials.The quantum information starts from discrete variables,and then is extended into the field of continuous variables.The preparation and control of Non-classical states,especially of quantum entanglement states,can be applied for the test of quantum mechnatics,and it can also be the important bases for quantaum information. Using entanglements,many quantum information and quantum measurement research work can be accomplished.Entanglement between more than two partites is going to be the key ingredient for quantum networks such as quantum teleportation networks,telecloning,controlled dense coding and quantum information between the quantum nodes established by quntum storage.In this thesis,we mainly investigated the research works about the continuous variables quantum entanglement as following:1.The review of squeezed and entanglement state is given,the quantum proporties of squeezing,correlation and entanglement generated from NOPO below and above threshold are discussed.2.The transfer of intensity quantum correlation is realized theoretically and experimentally.It is shown that the correlation between two separate lights with different frequency is established with quantum transfer.3.The time-correlation character of twin beams generated by Nondegenerate Optical Parametric Oscillator above threshold is experimentaly analyzed4.A scheme for generation of continuous variable tripartite entanglement using typeâ…¡second harmonic generation(SHG) process is proposed theoretically.Using the sufficient inseparability criterion for continuous variable tripartite entanglement,the quadrature noise correlation of reflected fundamental fields and generated harmonic field both below and above threshold of OPO are calculated.The dependences of correlation on the cavity parameters are also discussed.5.Analyzed the character of modulated laser by means of semiclassical theory.By optical homodyne tomography the Wigner function is reconstructed.The creative works are as follows:1.Experimentally analysed time-correlation character of twin beams generated from Nondegenerate Optical Parametric Oscillator.2.A scheme for generation of continuous variable tripartite entanglement using triply resonant typeâ…¡SHG processes is proposed and the three light modes of entangled state with different wavelengths are acquired theoretically.The experimental feasibility has also been analyzed.3.Reconstructed the Wigner function of a modulated laser experimentally.