UNAMBIGOUS SEQUENTIAL STATE DISCRIMINATION

Eunsang Kim, Tae Ryong Park

Chih‐Lung Chou

We review the problem of discriminating with minimum error among mixed quantum states, with emphasize on the analytically solved quantum ensembles.

Sonja Franke‐Arnold, John Jeffers

Tatiane da Silva Evangelista, Carlile Lavor, WILSON Ricardo Matos Rabelo

The problem of determining the state of a quantum system is a central task in any quantum information processing. However, there are limitations imposed by quantum mechanics on the possibilities to determine the state of a quantum system. For example, nonorthogonal states cannot be discriminated perfectly. In this paper, we propose a new method to calculate the inconclusive coefficients based on the solution of a quadratic system, replacing the determination of the roots of a polynomial of degree 8, used in an algorithm to quantum state discrimination previously defined in the literature. The new method simplifies the calculation of the inconclusive coefficients and can be extended very easily to any dimension. The method was written in Matlab and successfully applied to problems with different dimensions.

Miroslav Ježek

Alfred S. Goldhaber, Kenneth Watson

The theory of se~uential decays of an unstable system is studied.Examples include the se~uential emission of two or more photons by an excited atom which reaches its ground state via one or more intermediate leveis} and the decay of an unstable particle into other unstable particles.To describe these phenomena} a factorization of the Green's function is introduced.This leads to a simple} and intuitively obvious} description of se~uential decays.It also makes possible an assessment of the accuracy of this description.