Classical correlations for Generic States are Fragile under Decoherence

TL;DR

This paper investigates how classical correlations in quantum states behave under noise, showing they generally decrease with noise, and introduces methods to distinguish quantum channels based on classical correlators.

Contribution

It provides a detailed analysis of classical correlators under noise, connecting their behavior to quantum channels and proposing a discrimination method based on classical correlations.

Findings

Classical correlators decrease with increasing noise levels for most channels.

A connection between classical correlators of noisy and initial states is established.

Method to discriminate quantum channels using classical correlators of generalized W states.

Abstract

Quantum correlations typically decrease with increasing noise, although classical correlators (CCors) may rise for a particular class of states with noise. To analyse the behavior of classical correlation (CC) in the presence of local noise, we scrutinize the set of classical correlators, axiomatic CC measures like classical discord, and local work for Haar uniformly generated states. Like quantum correlation measures, we illustrate that when noise levels rise, the average value of the CC measures for noisy output states obtained from random input states decreases for most of the channels. We also demonstrate a connection between the CCors of the noise-affected multipartite states that are produced and the CCors of the initial states that exhibit exponential, polynomial, and constant behavior as the noise level changes. Moreover, based on CCors of the generalised N-qubit W state as input, we determine a method to discriminate between the quantum channels, namely phase damping, depolarizing, and amplitude damping channels. We also relate classical, quantum, and total correlation measures that exhibit a comparable reaction to decoherence for generic states.