We propose a scheme to implement ancilla-free 1 to 2 optimal phase covariant quantum cloning with atoms trapped in cavities.In the scheme the W-class state of three atoms,which are individually trapped in three spatia...We propose a scheme to implement ancilla-free 1 to 2 optimal phase covariant quantum cloning with atoms trapped in cavities.In the scheme the W-class state of three atoms,which are individually trapped in three spatially separated cavities,is deterministically generated.Then by the use of this W-class state and detection of the atomic state,an optimal ancilla-free 1 to 2 phase-covariant quantum cloning between two spatially separated trapped atoms can be realized.The scheme is robust for atomic spontaneous decay,cavity decay and photon leakage out of the fiber.In principle,an M+1-atom W-class state can be generated by using such an approach.Thus this scheme also can be generalized to implement 1 to M ancilla-free phase-covariant quantum cloning.展开更多
This paper considers a generalized spin star system which can be solved exactly, with the central spin-1/2 system embedded in an outer ring of N spin-1/2 particles（denoted as spin bath）. In this model, in addition...This paper considers a generalized spin star system which can be solved exactly, with the central spin-1/2 system embedded in an outer ring of N spin-1/2 particles（denoted as spin bath）. In this model, in addition to the central-outer interaction, each pair of nearest neighbour of the bath interacts within themselves. The general expressions of the eigenstates as well as the eigenvalues of the model are derived with the use of the symmetries of system. It analyses the quantum state transfer and the dynamical behaviour of entanglement created during quantum communication. It also analyses the efficiency of the configuration regarded as quantum phase covariant clone or decoherence model. Some interesting results are discovered concerning the properties of quantum communication in this model.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.11074002)the Personal Development Foundation of Anhui Province (Grant No.2008Z018)
文摘We propose a scheme to implement ancilla-free 1 to 2 optimal phase covariant quantum cloning with atoms trapped in cavities.In the scheme the W-class state of three atoms,which are individually trapped in three spatially separated cavities,is deterministically generated.Then by the use of this W-class state and detection of the atomic state,an optimal ancilla-free 1 to 2 phase-covariant quantum cloning between two spatially separated trapped atoms can be realized.The scheme is robust for atomic spontaneous decay,cavity decay and photon leakage out of the fiber.In principle,an M+1-atom W-class state can be generated by using such an approach.Thus this scheme also can be generalized to implement 1 to M ancilla-free phase-covariant quantum cloning.
基金Project supported by the National Science Foundation (Grant No 2007CB925204)
文摘This paper considers a generalized spin star system which can be solved exactly, with the central spin-1/2 system embedded in an outer ring of N spin-1/2 particles（denoted as spin bath）. In this model, in addition to the central-outer interaction, each pair of nearest neighbour of the bath interacts within themselves. The general expressions of the eigenstates as well as the eigenvalues of the model are derived with the use of the symmetries of system. It analyses the quantum state transfer and the dynamical behaviour of entanglement created during quantum communication. It also analyses the efficiency of the configuration regarded as quantum phase covariant clone or decoherence model. Some interesting results are discovered concerning the properties of quantum communication in this model.
