Null Values and Quantum State Discrimination

TL;DR

This paper introduces a null value measurement protocol for quantum state discrimination, combining partial-collapse and postselection, which enhances signal-to-noise ratio in optical experiments compared to strong measurements.

Contribution

The paper proposes a novel null value measurement scheme for quantum state discrimination and demonstrates its effectiveness through optical experiments.

Findings

Enhanced signal-to-noise ratio with null value protocol

Successful optical implementation of the scheme

Improved quantum state discrimination performance

Abstract

We present a measurement protocol for discriminating between two different quantum states of a qubit with high fidelity. The protocol, called null value, is comprised of a projective measurement performed on the system with a small probability (also known as partial-collapse), followed by a tuned postselection. We report on an optical experimental implementation of the scheme. We show that our protocol leads to an amplified signal-to-noise ratio (as compared with a straightforward strong measurement) when discerning between the two quantum states.