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With the aid of a quantum memory, the uncertainty about the measurement outcomes of two incompatible observables of a quantum system can be reduced. We investigate this measurement uncertainty bound by considering an additional quantum…

Quantum Physics · Physics 2013-02-15 Ming-Liang Hu , Heng Fan

We generalize measurement-device-independent quantum key distribution [ H.-K. Lo, M. Curty, and B. Qi, Phys. Rev. Lett. 108, 130503 (2012) ] to the scenario where the Bell-state measurement station contains also heralded quantum memories.…

Quantum Physics · Physics 2015-06-16 Silvestre Abruzzo , Hermann Kampermann , Dagmar Bruß

Quantum memory effects can be related to a bidirectional exchange of information between an open system and its environment, which in turn modifies the state and dynamical behavior of the last one. Nevertheless, non-Markovianity can also be…

Quantum Physics · Physics 2021-01-26 Adrián A. Budini

We investigate non-Markovianity measure using two-time correlation functions for open quantum systems. We define non-Markovianity measure as the difference between the exact two-time correlation function and the one obtained in the Markov…

Quantum Physics · Physics 2015-12-09 Md. Manirul Ali , Ping-Yuan Lo , Matisse Wei-Yuan Tu , Wei-Min Zhang

Quantum reservoir computing (QRC) harnesses driven quantum dynamics for time-series processing, yet the mechanisms behind the differing performance levels across its many implementations remain unclear. We show that apparently unrelated…

Quantum Physics · Physics 2026-03-24 Saud Čindrak , Lara Giebeler , Niclas Götting , Christopher Gies , Kathy Lüdge

Quantum regression theorem is a very useful result in open quantum system and extensively used for computing multi-point correlation functions. Traditionally it is derived for two-time correlators in the Markovian limit employing the…

Quantum Physics · Physics 2022-09-14 Sakil Khan , Bijay Kumar Agarwalla , Sachin Jain

Quantum reservoir computing (QRC) offers a promising framework for online quantum-enhanced machine learning tailored to temporal tasks, yet practical implementations with native memory capabilities remain limited. Here, we demonstrate an…

Memory effects play a fundamental role in the study of the dynamics of open quantum systems. There exist two conceptually distinct notions of memory discussed for quantum channels in the literature. In quantum information theory quantum…

Quantum Physics · Physics 2016-09-26 Carole Addis , Göktuğ Karpat , Chiara Macchiavello , Sabrina Maniscalco

Quantum-speed-limit (QSL) time captures the intrinsic minimal time interval for a quantum system evolving from an initial state to a target state. In single qubit open systems, it was found that the memory (non-Markovian) effect of…

Quantum Physics · Physics 2015-03-18 Chen Liu , Zhen-Yu Xu , Shiqun Zhu

In this paper we present a new approach for testing QM against the realism aspect of hidden variable theory (HVT). We consider successive measurements of non-commuting operators on a input spin $s$ state. The key point is that, although…

Quantum Physics · Physics 2007-05-23 Ali Ahanj , Pramod Joag

Quantum memories are enabling devices for extending the reach of quantum key distribution (QKD) systems. The required specifications for memories are, however, often considered too demanding for available technologies. One can change this…

Quantum Physics · Physics 2016-11-17 Nicoló Lo Piparo , Mohsen Razavi , Christiana Panayi

Establishing a notion of the quantum state that applies consistently across space and time could be a crucial step toward formulating a relativistic quantum theory. We give an operational meaning to multipartite quantum states over…

Quantum Physics · Physics 2026-04-14 Seok Hyung Lie , Hyukjoon Kwon

Recently, a series of different measures quantifying memory effects in the quantum dynamics of open systems has been proposed. Here, we derive a mathematical representation for the non-Markovianity measure based on the exchange of…

Understanding temporal processes and their correlations in time is of paramount importance for the development of near-term technologies that operate under realistic conditions. Capturing the complete multi-time statistics defining a…

Quantum Physics · Physics 2020-04-28 Philip Taranto

Quantum memory effects can be induced even when the degrees of freedom associated to the environment are not affected at all during the system evolution. In this paper, based on a bipartite representation of the system-environment dynamics,…

Quantum Physics · Physics 2022-01-03 Adrián A. Budini

Memoryless time evolutions are ubiquitous in nature but often correspond to a resolution-induced approximation, i.e. there are correlations in time whose effects are undetectable. Recent advances in the dynamical control of small quantum…

In the measurement of a continuous observable Q, the pure components of the reduced state do, in general, depend on the initial state. For measurements which attempt to localize the measured system in a certain region R, the localized wave…

High Energy Physics - Phenomenology · Physics 2007-05-23 Kai J. Druhl

Quantum reservoir computing (QRC) is a highly promising computational paradigm that leverages quantum systems as a computational resource for nonlinear information processing. While its application to time-series analysis is eagerly…

Quantum Physics · Physics 2024-11-18 Kaito Kobayashi , Keisuke Fujii , Naoki Yamamoto

We present a \emph{novel} and scalable supervised machine learning framework to predict open-quantum system dynamics and detect non-Markovian memory using only local ancilla measurements. A system qubit is coherently coupled to an ancilla…

Quantum Physics · Physics 2025-09-30 Ali Abu-Nada , Subhashish Banerjee

We use a Quantum Extreme Learning Machine for characterizing and estimating parameters of quantum dynamics generated by a tunable collision model. The input to the learning protocol consists of quantum states produced by successive system…

Quantum Physics · Physics 2026-03-19 Hajar Assil , Abderrahim El Allati , Gian Luca Giorgi