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Optimal quantum control of continuous variable systems poses a formidable computational challenge because of the high-dimensional character of the system dynamics. The framework of quantum invariants can significantly reduce the complexity…

Quantum control refers to our ability to manipulate quantum systems. This tutorial-style chapter focuses on the use of classical electromagnetic fields to steer the system dynamics. In this approach, the quantum nature of the control stems…

Quantum Physics · Physics 2025-12-05 Christiane P. Koch

We develop dynamical programming methods for the purpose of optimal control of quantum states with convex constraints and concave cost and bequest functions of the quantum state. We consider both open loop and feedback control schemes,…

Quantum Physics · Physics 2009-03-06 Viacheslav P. Belavkin , Antonio Negretti , Klaus Molmer

In quantum systems theory one of the fundamental problems boils down to: Given an initial state, which final states can be reached by the dynamic system in question? Formulated in the framework of bilinear control systems, the evolution…

Quantum Physics · Physics 2020-12-09 Frederik vom Ende

Quantum physics is a linear theory, so it is somewhat puzzling that it can underlie very complex systems such as digital computers and life. This paper investigates how this is possible. Physically, such complex systems are necessarily…

Quantum Physics · Physics 2024-03-12 George F R Ellis

Periodically-driven systems are ubiquitous in science and technology. In quantum dynamics, even a small number of periodically-driven spins leads to complicated dynamics. Hence, it is of interest to understand what constraints such dynamics…

Quantum Physics · Physics 2022-04-20 Tanmoy Pandit , Alaina M. Green , C. Huerta Alderete , Norbert M. Linke , Raam Uzdin

Non-Markovian reduced dynamics of an open system is investigated. In the case the initial state of the reservoir is the vacuum state, an approximation is introduced which makes possible to construct a reduced dynamics which is completely…

Quantum Physics · Physics 2017-08-23 Andrzej Kossakowski , Rolando Rebolledo

The evolution of particulate and multiphase systems can transition from dynamic regimes, governed by classical transport equations with well-defined damping coefficients, to anomalously slow relaxation described by rate equations when the…

Soft Condensed Matter · Physics 2025-08-20 Carlos E. Colosqui

Numerous lines of experimental, numerical and analytical evidence indicate that it is surprisingly easy to locate optimal controls steering quantum dynamical systems to desired objectives. This has enabled the control of complex quantum…

Quantum Physics · Physics 2015-05-13 Raj Chakrabarti , Herschel Rabitz

Recently remarkable progress in quantum technology has been witnessed. In view of this it is important to investigate an open quantum system as a model of such quantum devices. Quantum devices often require extreme conditions such as very…

Quantum Physics · Physics 2020-12-02 Shingo Kukita , Yasushi Kondo , Mikio Nakahara

Open quantum systems are traditionally described by decomposing the total Hilbert space into a system and an external environment, linked by an explicit interaction Hamiltonian. We propose an alternative framework in which the environment…

Quantum Physics · Physics 2026-04-01 Yu Su , Yao Wang

We show that the dynamics of any open quantum system that is initially correlated with its environment can be described by a set of (or less) completely positive maps, where d is the dimension of the system. Only one such map is required…

Quantum Physics · Physics 2019-10-30 Gerardo A. Paz-Silva , Michael J. W. Hall , Howard M. Wiseman

Any real interaction process produces many incompatible system versions, or realisations, giving rise to omnipresent dynamic randomness and universally defined complexity (arXiv:physics/9806002). Since quantum behaviour dynamically emerges…

General Physics · Physics 2014-01-30 Andrei P. Kirilyuk

Many quantum systems exhibit high sensitivity to their initial conditions, where microscopic quantum fluctuations can significantly influence macroscopic observables. Understanding how quantum states may influence the behavior of nonlinear…

Quantum-mechanical initial conditions for the fluctuations of the geometry can be assigned in excess of a given physical wavelength. The two-point functions of the scalar and tensor modes of the geometry will then inherit corrections…

High Energy Physics - Theory · Physics 2009-11-10 Massimo Giovannini

A quantum-mechanical system comes naturally equipped with a convex space: each (Hermitian) operator has a (real) expectation value, and the expectation value of the square any Hermitian operator must be non-negative. This space is of…

High Energy Physics - Lattice · Physics 2025-02-05 Scott Lawrence

Quantum systems are invariably open, evolving under surrounding influences rather than in isolation. Standard open quantum system methods eliminate all information on the environmental state to yield a tractable description of the system…

Quantum Physics · Physics 2014-09-26 Jake Iles-Smith , Neill Lambert , Ahsan Nazir

When manipulating a quantum system $S$, its surrounding system, or \textit{environment}, $E$ induces unwanted effects. It is mainly due to its vastness and the lack of knowledge about the Hamiltonian $H_{SE}$ that governs the dynamics…

Quantum Physics · Physics 2015-03-05 Masaki Owari , Koji Maruyama , Takeji Takui , Go Kato

A central aim of physics is to describe the dynamics of physical systems. Schrodinger's equation does this for isolated quantum systems. Describing the time evolution of a quantum system that interacts with its environment, in its most…

Quantum Physics · Physics 2012-08-16 Kavan Modi

Quantum coherence inherently affects the dynamics and the performances of a quantum machine. Coherent control can, at least in principle, enhance the work extraction and boost the velocity of evolution in an open quantum system. Using…

Quantum Physics · Physics 2018-12-10 Vasco Cavina , Andrea Mari , Alberto Carlini , Vittorio Giovannetti