Detecting and quantifying non-Markovianity via quantum direct cause

• URL: http://arxiv.org/abs/2506.23267v1
• Date: Sun, 29 Jun 2025 14:45:40 GMT
• Title: Detecting and quantifying non-Markovianity via quantum direct cause
• Authors: Shrikant Utagi, Prateek Chawla,
• Abstract summary: We study the efficacy of two recently introduced witnesses of non-Markovianity.<n>We show, through specific counterexamples taken from existing literature, that they can witness a process to be non-Markovian.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We study the efficacy of the two recently introduced witnesses of non-Markovianity, namely that based on temporal correlations in pseudo-density matrix and temporal steering correlations in detecting information backflow. We show, through specific counterexamples taken from existing literature, that they can witness a process to be non-Markovian where trace distance and entropic distinguishability measures may fail. We further show that, since the pseudo-density matrix is directly related to the Choi matrix of a channel via the partial transpose, it can be generalized to quantify the total quantum memory in any indivisible process. Moreover, we make an interesting observation that temporal steerable correlations-based measure may not capture eternal non-Markovianity hence may not be proportional to Choi-matrix-based methods, while pseudo-density matrix-based measures introduced in this work faithfully capture eternal non-Markovianity. Our work highlights important distinction between weak and strong forms of quantum direct cause in quantum mechanics when applied to open system dynamics.

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