Causal and Non-Causal Revivals of Information: A New Regime of Non-Markovianity in Quantum Stochastic Processes

Fuente: arXiv
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Main Authors: Buscemi, Francesco, Gangwar, Rajeev, Goswami, Kaumudibikash, Badhani, Himanshu, Pandit, Tanmoy, Mohan, Brij, Das, Siddhartha, Bera, Manabendra Nath
Format: Preprint
Published: 2024
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author Buscemi, Francesco
Gangwar, Rajeev
Goswami, Kaumudibikash
Badhani, Himanshu
Pandit, Tanmoy
Mohan, Brij
Das, Siddhartha
Bera, Manabendra Nath
author_facet Buscemi, Francesco
Gangwar, Rajeev
Goswami, Kaumudibikash
Badhani, Himanshu
Pandit, Tanmoy
Mohan, Brij
Das, Siddhartha
Bera, Manabendra Nath
contents The study of information revivals, witnessing the violation of certain data-processing inequalities, has provided an important paradigm in the study of non-Markovian quantum stochastic processes. Although often used interchangeably, we argue here that the notions of ``revivals'' and ``backflows'', i.e., flows of information from the environment back into the system, are distinct: an information revival can occur without any backflow ever taking place. In this paper, we examine in detail the phenomenon of non-causal revivals and relate them to the theory of short Markov chains and squashed non-Markovianity. We also provide an operational condition, in terms of system-only degrees of freedom, to witness the presence of genuine backflow that cannot be explained by non-causal revivals. As a byproduct, we demonstrate that focusing on processes with genuine backflows, while excluding those with only non-causal revivals, resolves the issue of non-convexity of Markovianity, thus enabling the construction of a convex resource theory of genuine quantum non-Markovianity.
format Preprint
id arxiv_https___arxiv_org_abs_2405_05326
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Causal and Non-Causal Revivals of Information: A New Regime of Non-Markovianity in Quantum Stochastic Processes
Buscemi, Francesco
Gangwar, Rajeev
Goswami, Kaumudibikash
Badhani, Himanshu
Pandit, Tanmoy
Mohan, Brij
Das, Siddhartha
Bera, Manabendra Nath
Quantum Physics
The study of information revivals, witnessing the violation of certain data-processing inequalities, has provided an important paradigm in the study of non-Markovian quantum stochastic processes. Although often used interchangeably, we argue here that the notions of ``revivals'' and ``backflows'', i.e., flows of information from the environment back into the system, are distinct: an information revival can occur without any backflow ever taking place. In this paper, we examine in detail the phenomenon of non-causal revivals and relate them to the theory of short Markov chains and squashed non-Markovianity. We also provide an operational condition, in terms of system-only degrees of freedom, to witness the presence of genuine backflow that cannot be explained by non-causal revivals. As a byproduct, we demonstrate that focusing on processes with genuine backflows, while excluding those with only non-causal revivals, resolves the issue of non-convexity of Markovianity, thus enabling the construction of a convex resource theory of genuine quantum non-Markovianity.
title Causal and Non-Causal Revivals of Information: A New Regime of Non-Markovianity in Quantum Stochastic Processes
topic Quantum Physics
url https://arxiv.org/abs/2405.05326