Hermitian conjugate measurement

TL;DR

This paper introduces a probabilistic reversing operation using the Hermitian conjugate of a measurement operator, enabling approximate recovery of a quantum state after disturbance while increasing information gain.

Contribution

It presents a novel class of reversing operations that improve state fidelity and information gain simultaneously, demonstrated with spin systems and feasible interactions.

Findings

Reversing operations can recover original quantum states with high probability.

The method increases both fidelity and information gain simultaneously.

Experimental feasibility is demonstrated with spin system interactions.

Abstract

We propose a new class of probabilistic reversing operations on the state of a system that was disturbed by a weak measurement. It can approximately recover the original state from the disturbed state especially with an additional information gain using the Hermitian conjugate of the measurement operator. We illustrate the general scheme by considering a quantum measurement consisting of spin systems with an experimentally feasible interaction and show that the reversing operation simultaneously increases both the fidelity to the original state and the information gain with such a high probability of success that their average values increase simultaneously.