Efficient optimal minimum error discrimination of symmetric quantum states
- Department of Information Engineering (DEI), University of Padua, Via Gradenigo 6/B, 35131, Padova (Italy)
This article deals with the quantum optimal discrimination among mixed quantum states enjoying geometrical uniform symmetry with respect to a reference density operator rho{sub 0}. It is well known that the minimal error probability is given by the positive operator-valued measure obtained as a solution of a convex optimization problem, namely a set of operators satisfying geometrical symmetry, with respect to a reference operator PI{sub 0} and maximizing Tr(rho{sub 0}PI{sub 0}). In this article, by resolving the dual problem, we show that the same result is obtained by minimizing the trace of a semidefinite positive operator X commuting with the symmetry operator and such that X>=rho{sub 0}. The new formulation gives a deeper insight into the optimization problem and allows to obtain closed-form analytical solutions, as shown by a simple but not trivial explanatory example. In addition to the theoretical interest, the result leads to semidefinite programming solutions of reduced complexity, allowing to extend the numerical performance evaluation to quantum communication systems modeled in Hilbert spaces of large dimension.
- OSTI ID:
- 21388700
- Journal Information:
- Physical Review. A, Vol. 81, Issue 1; Other Information: DOI: 10.1103/PhysRevA.81.012315; (c) 2010 The American Physical Society; ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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