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By using relative entropy of coherence, we characterize the coherence gain induced by some quantum evolutions, including the cohering power of unitary operations and the decohering power of quantum operations. We find that the cohering…

Quantum Physics · Physics 2016-07-28 Zhengjun Xi , Mingliang Hu , Yongming Li , Heng Fan

We study the optimal generation of entanglement between two qubits subject to local unitary control. With the only assumptions of linear control and unitary dynamics, by means of a numerical protocol based on the variational approach…

Quantum Physics · Physics 2009-11-13 Raffaele Romano , Alessio Del Fabbro

We analyze quantum coherence generated by non-interacting magnons in a ferromagnetic spin chain described by the isotropic Heisenberg model. The exact expression derived for the reduced density operator of an arbitrary subsystem reveals…

Quantum Physics · Physics 2025-09-23 V. C. Vieira , F. M. de Paula

Manipulation and quantification of quantum resources are fundamental problems in quantum physics. In the asymptotic limit, coherence distillation and dilution have been proposed by manipulating infinite identical copies of states. In the…

Quantum Physics · Physics 2018-10-02 Qi Zhao , Yunchao Liu , Xiao Yuan , Eric Chitambar , Xiongfeng Ma

Quantum technologies are developing powerful tools to generate and manipulate coherent superpositions of different energy levels. Envisaging a new generation of energy-efficient quantum devices, here we explore how coherence can be…

Quantum Physics · Physics 2017-09-06 Giulio Chiribella , Yuxiang Yang

Quantum thermodynamics allows for the interconversion of quantum coherence and mechanical work. Quantum coherence is thus a potential physical resource for quantum machines. However, formulating a general nonequilibrium thermodynamics of…

Quantum Physics · Physics 2025-11-05 Franklin L. S. Rodrigues , Eric Lutz

A bipartite system whose subsystems are fully quantum chaotic and coupled by a perturbative interaction with a tunable strength is a paradigmatic model for investigating how isolated quantum systems relax towards an equilibrium. It is found…

Optimal control theory is developed for the task of obtaining a primary objective in a subspace of the Hilbert space while avoiding other subspaces of the Hilbert space. The primary objective can be a state-to-state transition or a unitary…

Quantum Physics · Physics 2008-06-13 Jose P. Palao , Ronnie Kosloff , Christiane P. Koch

The characterization and control of quantum effects in the performance of thermodynamic tasks may open new avenues for small thermal machines working in the nanoscale. We study the impact of coherence in the energy basis in the operation of…

Quantum Physics · Physics 2021-04-14 Kenza Hammam , Yassine Hassouni , Rosario Fazio , Gonzalo Manzano

Non-equilibrium effects may have a profound impact on the performance of thermal devices performing thermodynamic tasks such as refrigeration or heat pumping. The possibility of enhancing the performance of thermodynamic operations by means…

Quantum Physics · Physics 2024-03-26 Kenza Hammam , Gonzalo Manzano , Gabriele De Chiara

We review the generation of random pure states using a protocol of repeated two qubit gates. We study the dependence of the convergence to states with Haar multipartite entanglement distribution. We investigate the optimal generation of…

Quantum Physics · Physics 2009-01-26 A. Borras , A. Majtey , M. Casas

Connections between the resource theories of coherence and purity (or non-uniformity) are well known for discrete-variable, finite-dimensional, quantum systems. We establish analogous results for continuous-variable systems, in particular…

Quantum Physics · Physics 2021-11-17 Giulio Gianfelici , Hermann Kampermann , Dagmar Bruß

Quantum superposition of energy eigenstates can appear autonomously in a single quantum two-level system coupled to a low-temperature thermal bath, if such coupling has a proper composite nature. We propose here a principally different and…

Quantum Physics · Physics 2023-12-18 Michal Kolář , Radim Filip

The resource theory of coherence studies the operational value of superpositions in quantum technologies. A key question in this theory concerns the efficiency of manipulation and inter-conversion of the resource. Here we solve this…

Quantifying quantum coherence is a key task in the resource theory of coherence. Here we establish a good coherence monotone in terms of a state conversion process, which automatically endows the coherence monotone with an operational…

Quantum Physics · Physics 2020-07-01 Deng-hui Yu , Li-qiang Zhang , Chang-shui Yu

Quantum coherence, encoded in the off-diagonal elements of a system's density matrix, is a key resource in quantum thermodynamics, fundamentally limiting the maximum extractable work known as ergotropy. While previous experiments have…

Quantum Physics · Physics 2025-12-04 Li Li , Silu Zhao , Yun-Hao Shi , Kai Xu , Heng Fan , Dongning Zheng , Zhongcheng Xiang

One of the principal objectives of quantum thermodynamics is to explore quantum effects and their potential beneficial role in thermodynamic tasks like work extraction or refrigeration. So far, even though several papers have already shown…

Quantum Physics · Physics 2019-04-22 C. L. Latune , I. Sinayskiy , F. Petruccione

This paper presents several results on performance analysis for a class of uncertain linear quantum systems subject to either quadratic or non-quadratic perturbations in the system Hamiltonian. Also, coherent guaranteed cost controllers are…

Quantum Physics · Physics 2014-04-16 Chengdi Xiang , Ian R. Petersen , Daoyi Dong

Quantum pseudorandomness, also known as unitary designs, comprise a powerful resource for quantum computation and quantum engineering. While it is known in theory that pseudorandom unitary operators can be constructed efficiently, realizing…

Quantum Physics · Physics 2019-07-24 Jun Li , Zhihuang Luo , Tao Xin , Hengyan Wang , David Kribs , Dawei Lu , Bei Zeng , Raymond Laflamme

Coherent states are derived for one-dimensional systems generated by supersymmetry from an initial Hamiltonian with a purely discrete spectrum for which the levels depend analytically on their subindex. It is shown that the algebra of the…

Quantum Physics · Physics 2023-04-13 David J. Fernandez C , Veronique Hussin , Oscar Rosas-Ortiz