Generation Of Non-classical Optical State At Optical Fiber Communication Wavelength And Its Application In Quantum Teleportation

With the continual development of quantum optical protocols and technologies,the studies on the experimental generations of nonclassical states of optical fields and their applications in quantum communication,quantum measurement,quantum computation and quantum internets have been extensively implemented,and significant achievements have already been obtained.One of the hot topics in current quantum optics region is to explore the possible applications of optical quantum states in quantum information and quantum measurements.Squeezed states of light with the quantum noise in a quadrature component lower than standard quantum noise limit(QNL)have been utilized in researches of quantum communication and quantum precise measurements to improve the information capacity and signal-to-noise ratio for breaking through the limitation of classical physics.Entangled states of optical field have determinate nonlocal quantum correlations among their submodes and thus provide basic resources for quantum information technique.They have been used in experimental researches on different types of quantum protocols such as quantum teleportation,quantum entanglement swapping,quantum storage,quantum computation,quantum key distribution and quantum cryptography,in which the experimental results in agreement with the theoretical prediction are obtained.Currently,researchers are devoting themselves to transferring the experimental achievements into practical applications.For constructing useful quantum information network we have to realize the long-distance transmission of quantum states firstly.Compared with free space,optical fiber channels can better avoid the influences of outside environment noises and have the intrinsic properties of uniform and stability.Hence,optical fibers can be used as the good long-distance transmission mediums of optical modes.Nonclassical optical states at the wavelength of 1.3 μm,which matches one of the low loss transmission windows of optical fibers,have potential applications in quantum communication.Thus the experimental preparation of optical quantum states is important to develop practical quantum information networks.I have completed two research subjects during my Ph.D study.Firstly,I theoretically analyzed the generation conditions of nonclassical states of light at 1.3 μm wavelength,which is a low loss transmission window of optical fibers,and then designed the corresponding experimental system.An optical parametric amplifier(OPA)involving a type-II quasi-phase-matching periodically poled KTi OPO4(PPKTP)crystal was built to produce nonclassical states of light.The single-mode squeezed state,entangled state and intensity difference squeezed state of light are respectively generated by the OPA via intracavity parametric down-conversion under different physical conditions.Then,the continuous variable(CV)quantum teleportation passing through 6.0 kilometer fiber channel is experimentally realized by using EPR entangled state of light at wavelength of 1.3 μm.The work provides a feasible experimental protocol and technical reference for long-distance CV quantum teleportation in optical fiber channels.The system used here could be applied as a primary element for CV quantum communication networks in future.The main contents of the doctoral dissertation:1.The phase-matching relations of type-II phase matched periodically poled crystal are theoretically discussed,and the different experimental conditions for generating single-mode squeezed state,two-mode Einstein-Podolsky-Rosen(EPR)entangled state and intensity difference squeezed state of light are analyzed,which show that different quantum states of light can be produced with an identical OPA by controlling its operation conditions.2.For experiments,we build an OPA consisting of a type-II quasi-phase-matched PPKTP crystal,with which single-mode squeezed state,EPR entangled stateand intensity difference squeezed state of light at 1.3 μm wavelength are respectively generated under different physical conditions.3.A bipartite entangled state of light is experimentally obtained by interferencing two single-mode squeezed states of light with a specified relative phase on a 50:50 beam splitter.The squeezed states of light are generated by a pair of degenerate OPAs with totally identical configurations.Two sub-modes of the generated entanglement are distributed to two distant parties,Alice and Bob,through optical fiber channels.The distance between Alice and Bob is 6 kilometer.Finally,the deterministic quantum teleportation over 6.0 kilometer fiber channel is experimentally accomplished.The creative works are shown as follows:1.Special phase-matching relations of type-II matched periodically poled crystal are analyzed and different experimental conditions for generating single-mode squeezed state,two-mode EPR entangled state and intensity difference squeezed state with an identical OPA are discussed.2.Single-mode squeezed state,EPR entangled state and intensity difference squeezed state of light at optical fiber communication wavelength are respectively generated by an OPA consisting of a type-II phase-matched PPKTP crystal,which provides a feasible reference for designing a multi-purpose non-classical optical source.3.Continuous variable quantum teleportation of optical coherent state through a 6 kilometer fiber channel is experimentally demonstrated for the first time by means of using optical entangled states at 1.3 μm,which provides a useful technical reference for building CV quantum teleportation networks.