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Proceedings Paper

A quantum state discrimination martingale
Author(s): Michael R. Frey
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Paper Abstract

A martingale appears in conclusive Bayesian discrimination of two quantum states subjected to a sequence of optimal weak measurements. This martingale is solely a function of the two system states and their respective probabilities at the time of each measurement, and it directly determines the evolving probability of discrimination error. Also, it is constant if and only if the states are pure. For strictly mixed quantum states the martingle is constant just on average, with the consequence that, with some probability, the realized discrimination error probability conditioned on prior measurements may be less (better) than the optimal Helstrom error probability. So for mixed states conditionally superoptimal discrimination is possible. This phenomenon is demonstrated numerically in an example.

Paper Details

Date Published: 25 April 2007
PDF: 9 pages
Proc. SPIE 6573, Quantum Information and Computation V, 65730W (25 April 2007); doi: 10.1117/12.717679
Show Author Affiliations
Michael R. Frey, Bucknell Univ. (United States)


Published in SPIE Proceedings Vol. 6573:
Quantum Information and Computation V
Eric J. Donkor; Andrew R. Pirich; Howard E. Brandt, Editor(s)

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