Statistics of exponentially decaying radiation of any nuclide always obeys the binomial stochastic distribution. The variance is derived for the number of atoms disintegrating in a time interval. The variance determin...Statistics of exponentially decaying radiation of any nuclide always obeys the binomial stochastic distribution. The variance is derived for the number of atoms disintegrating in a time interval. The variance determines the error of the disintegrations number. When the measuring time is short compared with the half life, then the Poisson stochastics is valid. Today, computers can be used to determine either distribution very easily. The dependence of absolute and relative error on the measuring time interval is examined, but here assuming the absence of the background contribution.展开更多
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
文摘Statistics of exponentially decaying radiation of any nuclide always obeys the binomial stochastic distribution. The variance is derived for the number of atoms disintegrating in a time interval. The variance determines the error of the disintegrations number. When the measuring time is short compared with the half life, then the Poisson stochastics is valid. Today, computers can be used to determine either distribution very easily. The dependence of absolute and relative error on the measuring time interval is examined, but here assuming the absence of the background contribution.
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.
