Generation Of High-dimensional Quantum Entangled States And Its Application In Quantum Communication

Thanks to the existence of quantum entanglement, quantum information hasincomparable advantages over classical information field determined. As a newinterdisciplinary field derived from the combination of quantum mechanics andclassical information science, quantum communication goes beyond the limitations ofclassical communication in safety performance, carrying capacity and transmissiondistance and so on, then it attracts more and more attentions. Moreover, the quantumentanglement is an indispensable resource and information carrier in quantumcommunication scheme and thus concerned, especially higher dimension meansstronger nonlocality and much more powerful capability and security performance.Nowadays, effective construction of quantum entanglement has become a hot topic inquantum information research.In this paper, we proposed two schemes of symmetric and asymmetric entangledqudits generation in the optical system. The first proposal is assisted with cross-phasemodulation, which is based on the weak cross-Kerr nonlinearity. It enables thesimplification of generation steps and the improvement of success probability.Moreover, it is flexible for the generation of symmetric entangled qudits witharbitrary dimensions only with the same device. In addition, with the cascade used ofthe modified module, the input independent qudits could be transformed intoentangled qudits with different forms, thus saving all the resources and the totalsuccess probability could reach1. The second proposal is for asymmetric entangledqutrits generation, which is heralded. Therefore the generated qutrits have fewrestrictions and can be used flexibly in the subsequent quantum informationprocessing. The success probability is not very high, due to the bunching effect ofmulti-photon interference. However, if a special single photon detector is available,the success probability can increase to the theoretical limit value.The generated symmetric and asymmetric entangled qudits in our paper can beapplied to a variety of quantum communication schemes, which expend the quantuminformation resources and design ideas of quantum communication scheme and it is convenient for the research of the operation of qudits and entangled qudits.