Unambiguous identification of coherent states II: Multiple resources

TL;DR

This paper extends unambiguous identification of coherent states to scenarios with multiple resources, demonstrating repeated use of reference states despite measurement disturbances and analyzing the impact of imperfections.

Contribution

It generalizes existing optical setups for unambiguous coherent state identification to multiple copies and explores the reusability of reference states after measurement.

Findings

Recovered reference states can be reused for multiple identifications.

Imperfections in state preparation affect the identification performance.

Multiple resources improve the robustness of the identification process.

Abstract

We consider unambiguous identification of coherent states of electromagnetic field. In particular, we study possible generalizations of an optical setup proposed in M. Sedl\'{a}k {\it et al.}, Phys. Rev. A {\bf 76}, 022326 (2007). We show how the unambiguous identification of coherent states can be performed in a general case when multiple copies of unknown and the reference states are available. We also investigate whether reference states after the measurement can be "recovered" and further used for subsequent unambiguous identification tasks. We show that in spite of the fact that the recovered reference states are disturbed by measurements they can be repeatedly used for unambiguous identifications. We analyze the role of various imperfections in preparation of the unknown and the reference coherent states on the performance of our unambiguous identification setup.