TY - JOUR
T1 - Multicopy programmable discrimination of general qubit states
JF - Physical Review A
Y1 - 2010
A1 - Sentís, Gael
A1 - Bagan, Emili
A1 - Calsamiglia, John
A1 - Muñoz-Tapia, Ramon
AB - Quantum state discrimination is a fundamental primitive in quantum statistics where one has to correctly identify the state of a system that is in one of two possible known states. A programmable discrimination machine performs this task when the pair of possible states is not a priori known but instead the two possible states are provided through two respective program ports. We study optimal programmable discrimination machines for general qubit states when several copies of states are available in the data or program ports. Two scenarios are considered: One in which the purity of the possible states is a priori known, and the fully universal one where the machine operates over generic mixed states of unknown purity. We find analytical results for both the unambiguous and minimum error discrimination strategies. This allows us to calculate the asymptotic performance of programmable discrimination machines when a large number of copies are provided and to recover the standard state discrimination and state comparison values as different limiting cases.
VL - 82
UR - http://link.aps.org/doi/10.1103/PhysRevA.82.042312
ER -