Causal and Noncausal Revivals of Information: A New Regime of Non-Markovianity in Quantum Stochastic Processes
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 noncausal 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 noncausal revivals. As a byproduct, we demonstrate that focusing on processes with genuine backflows, while excluding those with only noncausal revivals, resolves the issue of nonconvexity of Markovianity, thus enabling the construction of a convex resource theory of genuine quantum non-Markovianity.
Authors
- Francesco Buscemi (ORCID: https://orcid.org/0000-0001-9741-0628)
- Tanmoy Pandit (ORCID: https://orcid.org/0000-0002-2377-6181)
- Brij Mohan (ORCID: https://orcid.org/0000-0001-6606-5374)
- Siddhartha Das (ORCID: https://orcid.org/0000-0002-4523-5781)
- Himanshu Badhani (ORCID: https://orcid.org/0000-0002-1795-4164)
- Manabendra Nath Bera (ORCID: https://orcid.org/0000-0002-8329-2656)
- Kaumudibikash Goswami (ORCID: https://orcid.org/0000-0002-6603-8082)
- Rajeev Gangwar (ORCID: https://orcid.org/0000-0001-9507-6654)
Institutions
- Indian Institute of Science Education and Research Kolkata (IN)
- Indian Institute of Science Education and Research Mohali (IN)
- Hebrew University of Jerusalem (IL)
- Homi Bhabha National Institute (IN)
- Indian Institute of Science Education and Research, Bhopal (IN)
- Indian Institute of Science Education and Research Berhampur (IN)
- Indian Institute of Science Education and Research, Tirupati (IN)
- Nagoya University (JP)
- International Institute of Information Technology, Hyderabad (IN)
- University of Hong Kong (HK)
Publication Details
- Journal
- PRX Quantum
- Published
- 2025-04-23
- DOI
- https://doi.org/10.1103/prxquantum.6.020316
- Citations
- 6
- Primary Topic
- Quantum Mechanics and Applications
- Type
- article
- Field-Weighted Citation Impact
- 7.48
Funders
- John Templeton Foundation
- ITEA
- Department of Science and Technology, Ministry of Science and Technology, India
- Council of Scientific and Industrial Research, India
- Ministry of Education, Culture, Sports, Science and Technology
- Ministry of Electronics and Information technology
- International Institute of Information Technology, Hyderabad
- Japan Society for the Promotion of Science
- Science and Engineering Research Board