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According to a fundamental result in quantum computing, any unitary transformation on a composite system can be generated using so-called 2-local unitaries that act only on two subsystems. Beyond its importance in quantum computing, this…

Quantum Physics · Physics 2024-08-15 Iman Marvian

Light harvesting processes are often computationally studied from a time-dependent viewpoint, in line with ultrafast coherent spectroscopy experiments. Yet, natural processes take place in the presence of incoherent light, which induces a…

Chemical Physics · Physics 2021-04-14 Ignacio Loaiza , Artur F. Izmaylov , Paul Brumer

We compare quantum decoherence in generic regular and chaotic systems that interact with a thermal reservoir via a dipole coupling. Using a time-dependent, self-consistent approximation in the spirit of Hartree, we derive in the high…

Quantum Physics · Physics 2016-06-29 Allan Tameshtit , J. E. Sipe

This paper is concerned with constructing an optimal controller in the coherent quantum Linear Quadratic Gaussian problem. A coherent quantum controller is itself a quantum system and is required to be physically realizable. The use of…

Quantum Physics · Physics 2012-05-21 Igor G. Vladimirov , Ian R. Petersen

We investigate the fundamental limitations imposed by thermodynamics for creating correlations. Considering a collection of initially uncorrelated thermal quantum systems, we ask how much classical and quantum correlations can be obtained…

Macroscopic quantum superpositions are widely believed to be unobservable because large systems cannot be perfectly isolated from their environments. Here, we show that even under perfect isolation, intrinsic unitary dynamics with the…

Quantum Physics · Physics 2025-12-15 Gabriel Dias Carvalho , Pedro S. Correia , Thiago R. de Oliveira

The work considers an open qutrit system whose density matrix $\rho(t)$ evolution is governed by the Gorini-Kossakowski-Sudarshan-Lindblad master equation with simultaneous coherent (in the Hamiltonian) and incoherent (in the superoperator…

Quantum Physics · Physics 2024-07-12 Oleg Morzhin , Alexander Pechen

A Cahn-Hilliard equation with stochastic multiplicative noise and a random convection term is considered. The model describes isothermal phase-separation occurring in a moving fluid, and accounts for the randomness appearing at the…

Analysis of PDEs · Mathematics 2021-04-21 Luca Scarpa

This paper considers a class of uncertain linear quantum systems subject to uncertain perturbations in the system Hamiltonian. We present a method to design a coherent robust H-infinity controller so that the closed loop system is robustly…

Systems and Control · Computer Science 2015-09-10 Chengdi Xiang , Ian R. Petersen , Daoyi Dong

Quantum coherence as an asymmetry relative to a translation group generated by a Hermitian operator, is a necessary resource for the quantum parameter estimation. On the other hand, the sensitivity of the parameter estimation is known to be…

While questions on quantum simulation of ground state physics are mostly focussed on the realization of effective interactions, most work on quantum simulation of thermal physics explores the realization of dynamics towards a thermal mixed…

The interaction of a quantum system with its environment causes decoherence, setting a fundamental limit on the suitability of a system for quantum information processing. However, we show that if the quantum system consists of coupled…

Quantum Physics · Physics 2018-04-11 Helen Cammack , Peter Kirton , Paul Eastham , Jonathan Keeling , Brendon Lovett

Quantum entanglement is a key resource for quantum technologies, yet its efficient and high-fidelity generation remains a challenge due to the complexity of quantum dynamics. This paper presents a quantum optimal control framework to…

Quantum Physics · Physics 2025-07-15 Nahid Binandeh Dehaghani , A. Pedro Aguiar , Rafal Wisniewski

Nature, in the form of dissipation, inevitably intervenes in our efforts to control a quantum system. In this talk we show that although we cannot, in general, compensate for dissipation by coherent control of the system, such effects are…

Quantum Physics · Physics 2007-05-23 Allan I Solomon , Sonia G Schirmer

The introduction of the quantum analogue of a Carnot engine based on a bath comprising of particles with a small amount of coherence initiated an active line of research on the harnessing of different quantum resources for the enhancement…

Quantum Physics · Physics 2022-12-23 Kenza Hammam , Heather Leitch , Yassine Hassouni , Gabriele De Chiara

We describe a method to compute thermodynamic quantities in the harmonic approximation for identical bosons and fermions in an external confining field. We use the canonical partition function where only energies and their degeneracies…

Quantum Physics · Physics 2012-02-16 J. R. Armstrong , N. T. Zinner , D. V. Fedorov , A. S. Jensen

Quantum coherence profoundly alters classical thermodynamic expectations by modifying the structure and accessibility of probability distributions. Classically, transitions to lower-entropy states (local second-law violations) are…

Quantum Physics · Physics 2025-05-20 Andrei Tudor Patrascu

We introduce the quantitative measures characterizing the rates of decoherence and thermalization of quantum systems. We study the time evolution of these measures in the case of a quantum harmonic oscillator whose relaxation is described…

Quantum Physics · Physics 2009-11-06 V. V. Dodonov , S. S. Mizrahi , A. L. de Souza Silva

Quantum coherence is a prime resource in quantum computing and quantum communication. Quantum coherence of an arbitrary qubit state can be created at a remote location using maximally entangled state, local operation and classical…

Quantum Physics · Physics 2023-02-09 Jasleen Kaur , Shrobona Bagchi , Arun Kumar Pati

One of the fundamental questions in the emerging field of quantum thermodynamics is the role played by coherence in energetic processes that occur at the quantum level. Here, we address this issue by investigating two different quantum…

Quantum Physics · Physics 2021-01-04 Bertúlio de Lima Bernardo