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We find the necessary and sufficient condition under which two two-qubit mixed states can be purified into a pure maximally entangled state by local operations and classical communication. The optimal protocol for such transformation is…

Quantum Physics · Physics 2007-05-23 Enric Jane

Describing the thermodynamic properties of quantum systems far from equilibrium is challenging, in particular when the system is strongly coupled to its environment, or when memory effects cannot be neglected. Here, we address such regimes…

Mesoscale and Nanoscale Physics · Physics 2022-02-11 Matteo Carrega , Loris Maria Cangemi , Giulio De Filippis , Vittorio Cataudella , Giuliano Benenti , Maura Sassetti

It is not a general opinion that that a quantum system could be purified into a target eigenstate via repeated measurements on a coupled qubit rather than direct transitions in the Hamiltonian. The projective measurement on the ancillary…

Quantum Physics · Physics 2023-10-30 Jia-shun Yan , Jun Jing

A measurement-based quantum computer could consist of a local-gapped Hamiltonian system, whose thermal states --at sufficiently low temperature-- are universal resources for the computation. Initialization of the computer would correspond…

Quantum Physics · Physics 2015-06-18 G. H. Aguilar , T. Kolb , D. Cavalcanti , L. Aolita , R. Chaves , S. P. Walborn , P. H. Souto Ribeiro

Quantum state engineering of light is of great interest for quantum technologies, particularly generating non-classical states of light, and is often studied through quantum conditioning approaches. Recently, we demonstrated that such…

Quantum Physics · Physics 2026-03-24 J. Rivera-Dean , Th. Lamprou , E. Pisanty , M. F. Ciappina , P. Tzallas , M. Lewenstein , P. Stammer

We propose a quantum algorithm for the purification of a generic mixed state $\rho$ of a $n$-qudit system by using an ancillary $n$-qudit system. The algorithm is optimal in that (i) the number of ancillary qudits cannot be reduced, (ii)…

Quantum Physics · Physics 2009-05-04 Giuliano Benenti , Giuliano Strini

We present a quantum thermometry method utilizing an optomechanical system composed of an optical field coupled to a mechanical resonator for measuring the unknown temperature of a thermal bath. To achieve this, we connect a thermal bath to…

Quantum Physics · Physics 2024-12-06 Asghar Ullah , Ali Pedram , M. Tahir Naseem , Özgür E. Müstecaplıoğlu

Landauer's limit on heat dissipation during information erasure is critical as devices shrink, requiring optimal pure-state preparation to minimise errors. However, Nernst's third law states this demands infinite resources in energy, time,…

Quantum tunneling allows electrons to be transferred between two regions separated by an energetically forbidden barrier. Performing a position measurement that finds a particle in the barrier forces the tunneling electrons to transition…

Quantum Physics · Physics 2026-03-17 Rafael Sánchez , Alok Nath Singh , Andrew N. Jordan , Bibek Bhandari

Practical implementations of quantum technologies require preparation of states with a high degree of purity---or, in thermodynamic terms, very low temperatures. Given finite resources, the Third Law of thermodynamics prohibits perfect…

In this article we extend results from our previous work [Bendersky, de la Torre, Senno, Figueira and Ac\'in, Phys. Rev. Lett. 116, 230406 (2016)] by providing a protocol to distinguish in finite time and with arbitrarily high success…

By reformulating the first law of thermodynamics in the fashion of quantum-mechanical operators on the parameter manifold, we propose a universal class of quantum heat engines (QHE) using the multi-level quantum system as the working…

Quantum Physics · Physics 2007-05-23 H. T. Quan , P. Zhang , C. P. Sun

Quantum advantage arises from quantum states that cannot be efficiently simulated on a classical computer. Such states are characterised by a property known as nonstabiliserness. In this work, we investigate whether nonstabiliserness can be…

Cooling quantum systems is arguably one of the most important thermodynamic tasks connected to modern quantum technologies and an interesting question from a foundational perspective. It is thus of no surprise that many different…

Discrete combinatorial optimization consists in finding the optimal configuration that minimizes a given discrete objective function. An interpretation of such a function as the energy of a classical system allows us to reduce the…

Quantum Physics · Physics 2015-06-22 Sergio Boixo , Gerardo Ortiz , Rolando Somma

We introduce the idea of actually cooling quantum systems by means of incoherent thermal light, hence giving rise to a counter-intuitive mechanism of "cooling by heating". In this effect, the mere incoherent occupation of a quantum…

Quantum Physics · Physics 2012-03-28 A. Mari , J. Eisert

Optimal (reversible) processes in thermodynamics can be modelled as step-by-step processes, where the system is successively thermalized with respect to different Hamiltonians by an external thermal bath. However, in practice interactions…

The cooling effects of a quantum LC circuit coupled inductively with an ensemble of artificial qubits are investigated. The particles may decay independently or collectively through their interaction with the environmental vacuum…

Quantum Physics · Physics 2015-05-18 Mihai A. Macovei

Quantum thermodynamics and quantum entanglement represent two pivotal quantum resource theories with significant relevance in quantum information science. Despite their importance, the intricate relationship between these two theories is…

Quantum Physics · Physics 2025-03-26 Ray Ganardi , Piotr Masajada , Moein Naseri , Alexander Streltsov

We analyze quantum state-transfer optimization within hybrid open systems, from a "noisy" (write-in) qubit to its "quiet" counterpart (storage qubit). Intriguing interplay is revealed between our ability to avoid bath-induced errors that…

Quantum Physics · Physics 2015-05-20 B. M. Escher , G. Bensky , J. Clausen , G. Kurizki , L. Davidovich