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The passive states of a quantum system minimize the average energy among all the states with a given spectrum. We prove that passive states are the optimal inputs of single-jump lossy quantum channels. These channels arise from a weak…

Quantum Physics · Physics 2016-07-06 Giacomo De Palma , Andrea Mari , Seth Lloyd , Vittorio Giovannetti

Extracting useful work from quantum systems is a fundamental problem in quantum thermodynamics. In scenarios where rapid protocols are desired -- whether due to practical constraints or deliberate design choices -- a fundamental trade-off…

Quantum Physics · Physics 2026-04-23 Shoki Sugimoto , Takahiro Sagawa , Ryusuke Hamazaki

Work and quantum correlations are two fundamental resources in thermodynamics and quantum information theory. In this work we study how to use correlations among quantum systems to optimally store work. We analyse this question for isolated…

Non-unitary operations generated by an effective non-Hermitian Hamiltonian can be used to create quantum state manipulations which are impossible in Hermitian quantum mechanics. These operations include state preparation (or cooling) and…

Quantum Physics · Physics 2014-04-25 Raam Uzdin

We investigate the problem of preparing a pure Gaussian state via reservoir engineering. In particular, we consider a linear quantum system with a passive Hamiltonian and with a single reservoir which acts only on a single site of the…

Quantum Physics · Physics 2016-08-10 Shan Ma , Matthew J. Woolley , Ian R. Petersen , Naoki Yamamoto

We put forth a notion of optimality for extracting ergotropic work, derived from an energy constraint governing the necessary dynamics for work extraction in a quantum system. Within the traditional ergotropy framework, which predicts an…

Quantum Physics · Physics 2024-03-12 Pritam Halder , Srijon Ghosh , Saptarshi Roy , Tamal Guha

A suitable way of quantifying work for microscopic quantum systems has been constantly debated in the field of quantum thermodynamics. One natural approach is to measure the average increase in energy of an ancillary system, called the…

Quantum Physics · Physics 2018-05-16 Nelly Huei Ying Ng , Mischa Woods , Stephanie Wehner

We characterize the class of all physical operations that transform Gaussian states to Gaussian states. We show that this class coincides with that of all operations which can be performed on Gaussian states using linear optical elements…

Quantum Physics · Physics 2009-11-07 Géza Giedke , J. Ignacio Cirac

The paradigm of extracting work from isolated quantum system through a cyclic Hamiltonian process is a topic of immense research interest. The optimal work extracted under such process is termed as ergotropy [Europhys. Lett., 67 (4),…

Quantum Physics · Physics 2016-06-08 Amit Mukherjee , Arup Roy , Some Sankar Bhattacharya , Manik Banik

We consider ensembles of bipartite states resulting from a random passive Gaussian unitary applied to a fiducial pure Gaussian state. We show that the symplectic spectra of the reduced density operators concentrate around that of a thermal…

Quantum Physics · Physics 2019-12-02 Motohisa Fukuda , Robert Koenig

The quantum ergotropy quantifies the maximal amount of work that can be extracted from a quantum state without changing its entropy. Given that the ergotropy can be expressed as the difference of quantum and classical relative entropies of…

Quantum Physics · Physics 2021-08-26 Akira Sone , Sebastian Deffner

Work extraction from a heat engine in a cycle by a quantum mechanical device (quantum "piston") is analyzed. The standard definition of work fails in the quantum domain. The correct extractable work and its efficiency bound are shown to…

Quantum Physics · Physics 2013-10-11 D. Gelbwaser-Klimovsky , R. Alicki , G. Kurizki

We examine when it is possible to locally extract energy from a bipartite quantum system in the presence of strong coupling and entanglement, a task which is expected to be restricted by entanglement in the low-energy eigenstates. We fully…

Non-Gaussian states and operations are crucial for various continuous-variable quantum information processing tasks. To quantitatively understand non-Gaussianity beyond states, we establish a resource theory for non-Gaussian operations. In…

Quantum Physics · Physics 2018-05-23 Quntao Zhuang , Peter W. Shor , Jeffrey H. Shapiro

Quantum Non-Gaussian states are considered as a useful resource for many tasks in quantum information processing, from quantum metrology and quantum sensing to quantum communication and quantum key distribution. Another useful tool that is…

Quantum Physics · Physics 2021-08-31 Seid Koudia , Abdelhakim Gharbi

Active states, from which work can be extracted by time-dependent perturbations, are an important resource for quantum thermodynamics in the absence of heat baths. Here we characterize this resource, establishing a resource theory that…

Quantum Physics · Physics 2023-04-19 Swati , Uttam Singh , Giulio Chiribella

We show how the presence of entanglement in a bipartite Gaussian state can be detected by the amount of work extracted by a continuos variable Szilard-like device, where the bipartite state serves as the working medium of the engine. We…

Quantum Physics · Physics 2017-12-20 Matteo Brunelli , Marco G. Genoni , Marco Barbieri , Mauro Paternostro

Work extraction in quantum finite systems is an important issue in quantum thermodynamics. The optimal work extracted is called ergotropy, and it is achieved by maximizing the average work extracted over all the unitary cycles. However, an…

Quantum Physics · Physics 2024-04-10 Gianluca Francica , Luca Dell'Anna

In the context of quantum technologies over continuous variables, Gaussian states and operations are typically regarded as freely available, as they are relatively easily accessible experimentally. In contrast, the generation of…

Quantum Physics · Physics 2022-07-13 Oliver Hahn , Patric Holmvall , Pascal Stadler , Giulia Ferrini , Alessandro Ferraro

Although entropy is a necessary and sufficient quantity to characterize the order of work content for equal energetic (EE) states in the asymptotic limit, for the finite quantum systems, the relation is not so linear and requires detail…

Quantum Physics · Physics 2020-07-29 Mir Alimuddin , Tamal Guha , Preeti Parashar