Witnessing environment dimension through temporal correlations

Lucas B. Vieira, Simon Milz, Giuseppe Vitagliano, Costantino Budroni

Publications: Contribution to journalArticlePeer Reviewed


We introduce a framework to compute upper bounds for temporal correlations achievable in open quantum system dynamics, obtained by repeated measurements on the system. As these correlations arise by virtue of the environment acting as a memory resource, such bounds are witnesses for the minimal dimension of an effective environment compatible with the observed statistics. These witnesses are derived from a hierarchy of semidefinite programs with guaranteed asymptotic convergence. We compute non-trivial bounds for various sequences involving a qubit system and a qubit environment, and compare the results to the best known quantum strategies producing the same outcome sequences. Our results provide a numerically tractable method to determine bounds on multi-time probability distributions in open quantum system dynamics and allow for the witnessing of effective environment dimensions through probing of the system alone.
Original languageEnglish
Pages (from-to)1-25
Number of pages25
Publication statusPublished - 10 Jan 2024

Austrian Fields of Science 2012

  • 103025 Quantum mechanics

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