Quantum memory receiver for superadditive communication using binary coherent states

TL;DR

This paper introduces a quantum memory-based receiver architecture for classical communication using binary coherent states, demonstrating superadditivity and improved transmission rates through joint detection and collective readout.

Contribution

It proposes a novel quantum memory receiver scheme that enables superadditive communication with binary coherent states, combining linear optical transformations and quantum memories.

Findings

Demonstrates superadditivity in classical communication over quantum channels.

Analyzes two readout methods: direct detection and Dolinar receiver.

Shows potential for enhanced transmission rates using joint detection.

Abstract

We propose a simple architecture based on multimode quantum memories for collective readout of classical information keyed using a pair coherent states, exemplified by the well-known binary phase shift keying format. Such a configuration enables demonstration of the superadditivity effect in classical communication over quantum channels, where the transmission rate becomes enhanced through joint detection applied to multiple channel uses. The proposed scheme relies on the recently introduced idea to prepare Hadamard sequences of input symbols that are mapped by a linear optical transformation onto the pulse position modulation format [Guha, S. {\em Phys. Rev. Lett.}\ {\bf 2011}, {\em 106}, 240502]. We analyze two versions of readout based on direct detection and an optional Dolinar receiver which implements the minimum-error measurement for individual detection of a binary coherent state alphabet.