Probabilistic purification of noisy coherent states

TL;DR

This paper proposes a probabilistic method for purifying noisy coherent quantum states using linear optics and detection, which reduces noise more effectively than existing deterministic or classical methods, enhancing quantum communication.

Contribution

It introduces a novel probabilistic purification scheme for unknown noisy coherent states that improves noise reduction beyond traditional methods.

Findings

The scheme achieves lower noise in output states compared to deterministic methods.

It enhances classical communication capacity and quantum key distribution security.

The method is feasible with linear optics and standard detection techniques.

Abstract

A basic feasible probabilistic purification of unknown noisy coherent states, outgoing from different state preparations with unknown mean number of thermal photons, is proposed. The scheme is based only on a linear-optical network with an avalanche photo-diode or heterodyne (homodyne) detection used to post-select a successful processing. The suggested probabilistic method can produce an output state with a lower noise than both quantum deterministic and classical probabilistic distillation method. The purification applied in the state preparation can increase classical capacity of communication and security of quantum key distribution.