title: Frozen quantum coherence.
abstract: We analyze 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.
authors.affiliation: School of Mathematical Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Bromley
authors.affiliation: School of Mathematical Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.|Dipartimento di Fisica "E. R. Caianiello," Università degli Studi di Salerno, Via Giovanni Paolo II, I-84084 Fisciano (SA), Italy, and INFN Sezione di Napoli, Gruppo Collegato di Salerno, 84084 Fisciano (SA), Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Cianciaruso
authors.affiliation: School of Mathematical Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Adesso