Discriminating two nonorthogonal states against a noise channel by feed-forward control

TL;DR

This paper introduces a feed-forward control scheme that significantly enhances the discrimination of two nonorthogonal quantum states after passing through a noise channel, outperforming traditional minimum-error methods.

Contribution

The proposed feed-forward control scheme improves quantum state discrimination under noise, achieving near-perfect or better-than-initial discrimination in a deterministic or probabilistic manner.

Findings

Enhanced discrimination accuracy with FFC under amplitude damping noise

Achieves near-ideal discrimination for equal priors

Outperforms standard ME discrimination methods

Abstract

We propose a scheme by using the feed-forward control (FFC) to realize a better effect of discrimination of two nonorthogonal states after passing a noise channel based on the minimum- error (ME) discrimination. We show that the application of our scheme can highly improve the effect of discrimination compared with the ME discrimination without the FFC for any pair of nonorthogonal states and any degree of amplitude damping (AD). Especially, the effect of our optimal discrimination can reach that of the two initial nonorthogonal pure states in the presence of the noise channel in a deterministic way for equal a prior probabilities or even be better than that in a probabilistically way for unequal a prior probabilities.