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Advantages of using a low-energy effective theory to study bound state properties are briefly discussed, and a nonperturbative implementation of such an effective theory is described within the context of nonrelativistic quantum mechanics.…

High Energy Physics - Phenomenology · Physics 2009-10-31 Richard Hill

We study the possibility of deterministic protocols for extracting work from quantum systems. Focusing on the two-point measurement work extraction scenario, we prove that, with enough copies of the system, such zero-fluctuation protocols…

Quantum Physics · Physics 2024-07-15 Raffaele Salvia , Vittorio Giovannetti

Maximizing the amount of work harvested from an environment is important for a wide variety of biological and technological processes, from energy-harvesting processes such as photosynthesisto energy storage systems such as fuels and…

Free energy fixes the maximum work of a thermodynamic process once the state and Hamiltonian are specified. A work-extraction task asks a different question: how much average work can a single device realize across several preparations and…

Quantum Physics · Physics 2026-05-06 Sumit Rout , Aravinth Balaji Ravichandran , Paweł Horodecki , Anubhav Chaturvedi

Energy extraction from quantum batteries by means of completely positive trace-preserving (CPTP) maps leads to the concept of CPTP-local passive states, which identify bipartite states from which no energy can be squeezed out by applying…

Quantum Physics · Physics 2024-06-19 Aparajita Bhattacharyya , Kornikar Sen , Ujjwal Sen

Suppose that the Hamiltonian acting on a quantum system is unknown and one wants to determine what is the Hamiltonian. We show that in general this requires a time $\Delta t$ which obeys the uncertainty relation $\Delta t \Delta H \gtrsim…

Quantum Physics · Physics 2009-11-07 Y. Aharonov , S. Massar , S. Popescu

Quantum batteries, small-scale energy storage devices based on quantum systems, offer the potential for enhanced charging performance through quantum effects such as coherence and collectivity. In this work, we study the collective charging…

Quantum Physics · Physics 2026-03-31 Chayan Purkait , B. Prasanna Venkatesh , Gentaro Watanabe

Considering the emerging applications of quantum technologies, studying energy storage and usage at the quantum level is of great interest. In this context, there is a significant contemporary interest in studying ergotropy, the maximum…

Quantum Physics · Physics 2025-08-26 Jitendra Joshi , T. S Mahesh

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

Although implementing shortcuts to adiabaticity (STA) in open quantum systems remains challenging due to the complex control schemes required for such systems, their powerful ability to rapidly steer the system toward target states and…

Quantum Physics · Physics 2025-11-11 Sh. Ebrahimi , S. Salimi , F. T. Tabesh , A. S. Khorashad

The maximum unitarily extractable work from a quantum system -- ergotropy -- is the basic principle behind quantum batteries, a rapidly emerging field. This work studies ergotropy in two quantum chaotic systems, the quantum kicked top and…

Quantum Physics · Physics 2025-08-11 Sreeram PG , J. Bharathi Kannan , S. Harshini Tekur , M. S. Santhanam

Quantum battery concerns about population redistribution and energy dispatch over controllable quantum systems. Under unitary transformation, ergotropy rather than energy plays an essential role in describing the accumulated useful work.…

Quantum Physics · Physics 2024-12-10 Shi-fan Qi , Jun Jing

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…

We consider work extraction from $N$ copies of a quantum system. When the same work-extraction process is implemented on each copy, the relative size of fluctuations is expected to decay as $1/\sqrt{N}$. Here, we consider protocols where…

Quantum Physics · Physics 2019-08-15 Martí Perarnau-Llobet , Raam Uzdin

"A battery powers a device" can be read as "work stored in the battery is being transported to the device." In quantum batteries, the total amount of stored work can be measured by ergotropy, which is the maximal work extractable by unitary…

Quantum Physics · Physics 2025-01-20 Rick P. A. Simon , Janet Anders , Karen V. Hovhannisyan

We identify the conditions for local passivity for shared quantum batteries with local Hamiltonians. For locally passive states of two-qubit batteries, we find the relation of their entanglement content with the amount of energy that can be…

Quantum Physics · Physics 2021-09-29 Kornikar Sen , Ujjwal Sen

We theoretically analyze the Photosystem II reaction center using a quantum master equation approach, where excitonic and charge-transfer rates are computed at the Redfield and F\"orster levels with realistic spectral densities. The focus…

Chemical Physics · Physics 2025-07-08 Trishna Kalita , Manash Jyoti Sarmah , Javed Akhtar , Himangshu Prabal Goswami

Given a closed quantum system, the states that can be reached with a cyclic process are those with the same spectrum as the initial state. Here we prove that, under a very general assumption on the Hamiltonian, the distribution of the mean…

Quantum Physics · Physics 2021-08-04 Raffaele Salvia , Vittorio Giovannetti

We extend the notion of estimation entropy of autonomous dynamical systems proposed by Liberzon and Mitra [1] to nonlinear dynamical systems with uncertain inputs with bounded variation. We call this new notion the {$\epsilon$}-estimation…

Systems and Control · Electrical Eng. & Systems 2023-11-14 Hussein Sibai , Sayan Mitra

We consider the problem of learning the Hamiltonian of a quantum system from estimates of Gibbs-state expectation values. Various methods for achieving this task were proposed recently, both from a practical and theoretical point of view.…

Quantum Physics · Physics 2024-10-31 Adam Artymowicz , Hamza Fawzi , Omar Fawzi , Samuel O. Scalet