Indirect measurement for optimal quantum communication enhanced by binary non-standard coherent states

Abstract

It is well known that the Helstrom bound can be improved by generalizing the form of a coherent state. Thus, designing a quantum measurement achieving the improved Helstrom bound is important for novel quantum communication. In this paper, we analytically show that the improved Helstrom bound can be achieved by a projective measurement composed of orthogonal non-standard Schrödinger cat states. Moreover, we numerically show that the improved Helstrom bound can be nearly achieved by an indirect measurement based on the Jaynes–Cummings model. As the Jaynes–Cummings model describes an interaction between a light and a two-level atom, we emphasize that the indirect measurement considered in this paper has potential to be experimentally implemented.