Quantifying information flow in quantum processes

: Santos, Leonardo S. V.; Xu, Zhen-Peng; Piilo, Jyrki; Guehne, Otfried

Publisher: American Physical Society (APS)

: COLLEGE PK

: 2025

: Physical Review A

: PHYS REV A

: 022201

: 112

: 2

: 12

: 2469-9926

: 2469-9934

DOI: https://doi.org/10.1103/5211-h7g2

: https://doi.org/10.1103/5211-h7g2

: https://research.utu.fi/converis/portal/detail/Publication/499702804

We present a framework for quantifying information flow within general quantum processes. For this purpose, we introduce the signaling power of quantum channels and discuss its relevant operational properties. This function supports extensions to higher-order maps, enabling the evaluation of information flow in general quantum causal networks and processes with indefinite causal order. Furthermore, our results offer a rigorous approach to information dynamics in open systems that applies also in the presence of initial system-environment correlations, and allows for the distinction between classical and quantum information backflow.

5211-h7g2.pdf

:
We thank Roope Uola and Kimmo Luoma for discussions and Dariusz Chruscinski and Simon Milz for key remarks. This work was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation, Projects No. 447948357 and 440958198) , the Sino-German Center for Research Promotion (Project No. M-0294) , and the German Ministry of Education and Research (Project QuKuK, BMBF Grant No. 16KIS1618K) . Z.-P.X. acknowledges support from National Natural Science Foundation of China (Grant No. 12305007) and Anhui Provincial Natural Science Foundation (Grant No. 2308085QA29) . L.S.V.S. acknowledges support from the House of Young Talents of the University of Siegen.