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Valid transformations between quantum states are necessarily described by completely positive maps, instead of just positive maps. Positive but not completely positive maps such as the transposition map cannot be implemented due to the…

Quantum Physics · Physics 2019-06-03 Qingxiuxiong Dong , Marco Túlio Quintino , Akihito Soeda , Mio Murao

We extend the concept of stochastic energy extraction from quantum batteries to the scenario where both positive operator-valued (POV) and physically realizable non-positive operator-valued measurements (NPOVMs) are applied on the auxiliary…

Quantum Physics · Physics 2025-04-15 Paranjoy Chaki , Aparajita Bhattacharyya , Kornikar Sen , Ujjwal Sen

We exhibit a two-parameter family of bipartite mixed states $\rho_{bc}$, in a $d\otimes d$ Hilbert space, which are negative under partial transposition (NPT), but for which we conjecture that no maximally entangled pure states in $2\otimes…

The theory of positive maps plays a central role in operator algebras and functional analysis, and has countless applications in quantum information science. The theory was originally developed for operators acting on complex Hilbert…

Quantum Physics · Physics 2023-06-07 Giulio Chiribella , Kenneth R. Davidson , Vern I. Paulsen , Mizanur Rahaman

We investigate the role of energy-invariant assistants in energy extraction from quantum batteries. To this end, for energy extraction, we restrict ourselves to unitaries that jointly act on the battery and the assistant but preserve the…

Quantum Physics · Physics 2026-04-23 Paranjoy Chaki , Aparajita Bhattacharyya , Kornikar Sen , Ujjwal Sen

Ergotropy provides a fundamental measure of the extractable work from a quantum system and, consequently, of the maximal useful energy, or charge, stored within it. Understanding how this quantity can be manipulated and transformed…

Quantum Physics · Physics 2026-04-30 André H. A. Malavazi , Borhan Ahmadi , Paweł Horodecki , Pedro R. Dieguez

Maximum quantum work extraction is generally defined in terms of the ergotropy functional, no matter how experimentally complicated is the implementation of the optimal unitary allowing for it, especially in the case of multipartite…

Quantum Physics · Physics 2025-01-27 Riccardo Castellano , Ranieri Nery , Kyrylo Simonov , Donato Farina

We present a simple quantum interactive proof (QIP) protocol using the quantum state teleportation (QST) and quantum energy teleportation (QET) protocols. QET is a technique that allows a receiver at a distance to extract the local energy…

Quantum Physics · Physics 2024-06-18 Kazuki Ikeda , Adam Lowe

We study quantum processes, as one parameter families of differentiable completely positive and trace preserving (CPTP) maps. Using different representations of the generator, and the Sylvester criterion for positive semi-definite matrices,…

Quantum Physics · Physics 2019-09-17 Gustavo Montes Cabrera , David Davalos , Thomas Gorin

Strong local passivity is a property of multipartite quantum systems from which it is impossible to extract energy locally. Surprisingly, if the strong local passive state displays entanglement, it could be possible to locally activate…

Non-locality without entanglement is a rather counter-intuitive phenomenon in which information may be encoded entirely in product (unentangled) states of composite quantum systems in such a way that local measurement of the subsystems is…

Quantum Physics · Physics 2017-03-08 Sarah Croke , Stephen M Barnett

We study the feasibility of extracting a pure entangled state of non-complementary, and potentially well separated, regions of a quantum many-body system. It is shown that this can indeed be accomplished in non-equilibrium scenarios as well…

Quantum Physics · Physics 2009-07-14 J. Molina-Vilaplana , H. Wichterich , V. E. Korepin , S. Bose

We study the distinguishability of bipartite quantum states by Positive Operator-Valued Measures with positive partial transpose (PPT POVMs). The contributions of this paper include: (1). We give a negative answer to an open problem of [M.…

Quantum Physics · Physics 2014-04-02 Nengkun Yu , Runyao Duan , Mingsheng Ying

In quantum information and computation, the generation of entanglement through unitary gates remains a significant and active area of research. However, there are states termed as absolutely separable, from which entanglement cannot be…

Quantum Physics · Physics 2026-02-13 Bivas Mallick , Saheli Mukherjee , Nirman Ganguly , A. S. Majumdar

Passive states are special configurations of a quantum system which exhibit no energy decrement at the end of an arbitrary cyclic driving of the model Hamiltonian. When applied to an increasing number of copies of the initial density…

Quantum Physics · Physics 2020-06-02 Raffaele Salvia , Vittorio Giovannetti

Quantum batteries, composed of quantum cells, are expected to outperform their classical analogs. The origin of such advantages lies in the role of quantum correlations, which may arise during the charging and discharging processes…

The No Low-energy Trivial States (NLTS) conjecture of Freedman and Hastings, 2014 -- which posits the existence of a local Hamiltonian with a super-constant quantum circuit lower bound on the complexity of all low-energy states --…

Quantum Physics · Physics 2022-01-26 Anurag Anshu , Chinmay Nirkhe

We investigate a two-qubit quantum battery where coherent charger-battery coupling competes with non-Markovian environmental interactions. By tuning the coupling strengths and detuning, we identify regimes in which environmental memory…

Quantum Physics · Physics 2026-04-14 Meysam Helmi Barati Farimani , Ali Mortezapour

We consider a classical harmonic driving field as the energy charger for the quantum batteries, which consist of an ensemble of two-level atoms. The maximum stored energy and the final state are derived analytically with the optimal driving…

Quantum Physics · Physics 2019-05-15 Yu-Yu Zhang , Tian-Ran Yang , Libin Fu , Xiaoguang Wang

Quantum algorithms for estimating the ground state energy of a quantum system often operate by preparing a classically accessible quantum state and then applying quantum phase estimation. Whether this approach yields quantum advantage…

Quantum Physics · Physics 2026-02-25 Daochen Wang