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Quantum systems out of equilibrium are presently a subject of active research, both in theoretical and experimental domains. In this work we consider time-periodically modulated quantum systems which are in contact with a stationary…

Quantum Gases · Physics 2017-12-06 V. Volokitin , A. Liniov , I. Meyerov , M. Hartmann , M. Ivanchenko , P. Hänggi , S. Denisov

Quantum metrology leverages quantum resources such as entanglement and squeezing to enhance parameter estimation precision beyond classical limits. While optimal quantum control strategies can assist to reach or even surpass the Heisenberg…

Quantum Physics · Physics 2025-10-17 Qifei Wei , Shengshi Pang

This paper discusses fully coherent quantum feedback control, in which the sensors, controller, and actuators are quantum systems and interact coherently with the system to be controlled: as a result, the entire feedback loop is coherent.…

Quantum Physics · Physics 2007-05-23 Seth Lloyd

Measuring the power spectral density of a stochastic process, such as a stochastic force or magnetic field, is a fundamental task in many sensing applications. Quantum noise is becoming a major limiting factor to such a task in future…

This work introduces the Schmidt quantum compressor, an innovative approach to quantum data compression that leverages the principles of Schmidt decomposition to encode quantum information efficiently. In contrast to traditional variational…

Quantum Physics · Physics 2025-08-06 Israel F. Araujo , Hyeondo Oh , Nayeli A. Rodríguez-Briones , Daniel K. Park

This article considers some control problems for closed and open two-level quantum systems. The closed system's dynamics is governed by the Schr\"odinger equation with coherent control. The open system's dynamics is governed by the…

Quantum Physics · Physics 2023-12-01 Oleg V. Morzhin , Alexander N. Pechen

Scrambling quantum systems have attracted attention as effective substrates for temporal information processing. Here we consider a quantum reservoir processing framework that captures a broad range of physical computing models with quantum…

The Brownian dynamics of the density operator for a quantum system interacting with a classical heat bath is described using a stochastic, non-linear Liouville equation obtained from a variational principle. The environment's degrees of…

Quantum Physics · Physics 2015-06-26 M. Grigorescu

We give an introduction to feedback control in quantum systems, as well as an overview of the variety of applications which have been explored to date. This introductory review is aimed primarily at control theorists unfamiliar with quantum…

Quantum Physics · Physics 2007-05-23 Kurt Jacobs

Robust performance of control schemes for open quantum systems is investigated under classical uncertainties in the generators of the dynamics and nonclassical uncertainties due to decoherence and initial state preparation errors. A…

Optimization and Control · Mathematics 2024-06-24 Sophie G. Schirmer , Frank C. Langbein , Carrie A. Weidner , Edmond Jonckheere

High-quality control is a fundamental requirement for quantum computation, but practically it is often hampered by the presence of various types of noises, which can be static or time-dependent. In many realistic scenarios, multiple noise…

Quantum Physics · Physics 2024-03-04 Bowen Shao , Xiaodong Yang , Ran Liu , Yue Zhai , Dawei Lu , Tao Xin , Jun Li

Quantum sensing harnesses the unique properties of quantum systems to enable precision measurements of physical quantities such as time, magnetic and electric fields, acceleration, and gravitational gradients well beyond the limits of…

Quantum Physics · Physics 2025-07-23 Ivana Nikoloska , Ruud Van Sloun , Osvaldo Simeone

Critical quantum metrology relies on the extreme sensitivity of a system's eigenstates near the critical point of a quantum phase transition to Hamiltonian perturbations. This means that these eigenstates are extremely sensitive to all the…

Quantum Physics · Physics 2025-06-12 George Mihailescu , Steve Campbell , Karol Gietka

Realistic multi-qubit noise processes often result in error mechanisms that are not captured by the probabilistic, Markovian error models commonly employed in circuit-level analyses of quantum fault-tolerance. By working within an…

We investigate the presence of memory in the sequential measurement statistics of an open quantum system, as witnessed by the departure from the quantum regression theorem (QRT), that is, the possibility to predict multitime probabilities…

Quantum Physics · Physics 2026-05-08 Paolo Luppi , Claudia Benedetti , Andrea Smirne

A dynamical decoupling method is presented which is based on embedding a deterministic decoupling scheme into a stochastic one. This way it is possible to combine the advantages of both methods and to increase the suppression of undesired…

Quantum Physics · Physics 2007-05-23 Oliver Kern , Gernot Alber

Analog quantum simulators have provided key insights into quantum many-body dynamics. However, in such systems, both coherent and incoherent errors limit their scalability, hindering simulations in regimes that challenge classical…

The optimal control problem for open quantum systems can be formulated as a time-dependent Lindbladian that is parameterized by a number of time-dependent control variables. Given an observable and an initial state, the goal is to tune the…

Quantum Physics · Physics 2024-05-30 Wenhao He , Tongyang Li , Xiantao Li , Zecheng Li , Chunhao Wang , Ke Wang

Finding a physically consistent approach to modelling interactions between classical and quantum systems is a highly nontrivial task. While many proposals based on various mathematical formalisms have been made, most of these efforts run…

Quantum Physics · Physics 2022-10-05 Marcel Reginatto , Sebastian Ulbricht

We derive the quantum stochastic master equation for bosonic systems without measurement theory but control theory. It is shown that the quantum effect of the measurement can be represented as the correlation between dynamical and…

Quantum Physics · Physics 2007-05-23 M. Yanagisawa