Frozen Quantum Coherence

TL;DR

This paper investigates conditions under which quantum coherence remains unaffected by noise in open quantum systems, revealing universal criteria for coherence freezing in multi-qubit systems and analytical results for specific two-qubit states.

Contribution

It identifies universal conditions for coherence freezing in multi-qubit systems and provides analytical formulas for certain two-qubit states, advancing understanding of quantum coherence dynamics.

Findings

Coherence can be completely unaffected by noise under specific conditions.

Universal criteria for coherence freezing are established for even N-qubit systems.

Analytical expressions for coherence measures are derived for two-qubit states with maximally mixed marginals.

Abstract

We analyse under which dynamical conditions the coherence of an open quantum system is totally unaffected by noise. For a single qubit, specific measures of coherence are found to freeze under different conditions, with no general agreement between them. Conversely, for an N-qubit system with even N, we identify universal conditions in terms of initial states and local incoherent channels such that all bona fide distance-based coherence monotones are left invariant during the entire evolution. This finding also provides an insightful physical interpretation for the freezing phenomenon of quantum correlations beyond entanglement. We further obtain analytical results for distance-based measures of coherence in two-qubit states with maximally mixed marginals.