Residual and Destroyed Accessible Information after Measurements

TL;DR

This paper introduces a framework to quantify the information extracted, destroyed, and residual in quantum measurements, especially in non-demolition scenarios, with applications to coherent state discrimination.

Contribution

It proposes a novel framework to characterize quantum measurements based on information dynamics, enhancing understanding of measurement impacts in quantum communication.

Findings

Framework effectively characterizes information flow in quantum measurements.

Application to coherent states demonstrates practical utility.

Provides insights into residual information in non-demolition measurements.

Abstract

When quantum states are used to send classical information, the receiver performs a measurement on the signal states. The amount of information extracted is often not optimal due to the receiver's measurement scheme and experimental apparatus. For quantum non-demolition measurements, there is potentially some residual information in the post-measurement state, while part of the information has been extracted and the rest is destroyed. Here, we propose a framework to characterize a quantum measurement by how much information it extracts and destroys, and how much information it leaves in the residual post-measurement state. The concept is illustrated for several receivers discriminating coherent states.