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Causal diamonds are known to have thermal behavior that can be probed by finite-lifetime observers equipped with energy-scaled detectors. This thermality can be attributed to the time evolution of observers within the causal diamond,…

Quantum Physics · Physics 2025-01-03 H. E. Camblong , A. Chakraborty , P. Lopez-Duque , C. Ordóñez

The effective Hamiltonian serves as the conceptual pivot of quantum engineering, transforming physical complexity into programmable logic; yet, its construction remains compromised by the mathematical non-uniqueness of block…

Quantum Physics · Physics 2026-02-04 Hao-Yu Guan , Xiao-Long Zhu , Yu-Hang Dang , Xiu-Hao Deng

We consider the problem of decoherence and relaxation of open bosonic quantum systems from a perspective alternative to the standard master equation or quantum trajectories approaches. Our method is based on the dynamics of expectation…

Quantum Physics · Physics 2009-11-13 D. A. R. Dalvit , G. P. Berman , M. Vishik

Thermodynamics relies on the possibility to describe systems composed of a large number of constituents in terms of few macroscopic variables. Its foundations are rooted into the paradigm of statistical mechanics, where thermal properties…

Quantum Physics · Physics 2016-10-04 Antonella De Pasquale , Davide Rossini , Rosario Fazio , Vittorio Giovannetti

Existing algorithms for the optimal control of quantum observables are based on locally optimal steps in the space of control fields, or as in the case of genetic algorithms, operate on the basis of heuristics that do not explicitly take…

Quantum Physics · Physics 2007-08-27 Raj Chakrabarti , Rebing Wu , Herschel Rabitz

Useful quantum metrology requires nonclassical states with a high particle number and (close to) the optimal exploitation of the state's quantum correlations. Unfortunately, the single-particle detection resolution demanded by conventional…

Quantum Physics · Physics 2017-11-08 Samuel P. Nolan , Stuart S. Szigeti , Simon A. Haine

A genuine feature of projective quantum measurements is that they inevitably alter the mean energy of the observed system if the measured quantity does not commute with the Hamiltonian. Compared to the classical case, Jacobs proved that…

Statistical Mechanics · Physics 2015-06-10 Kay Brandner , Michael Bauer , Michael T. Schmid , Udo Seifert

The paper gives a systematic review of the basic ideas of (non-relativistic) quantum mechanics including all changes that result from previous work of the authors. This shows that the new theory is self-consistent and (in certain sense)…

Quantum Physics · Physics 2011-02-24 Petr Hajicek , Jiri Tolar

Providing entanglement for the design of quantum technologies in the presence of noise constitutes today's main challenge in quantum information science. A framework is required that assesses the build-up of entanglement in realistic…

Quantum Physics · Physics 2026-01-26 Julien Pinske , Laura Ares , Benjamin Hinrichs , Martin Kolb , Jan Sperling

The main power of quantum sensors is achieved when the probe is composed of several particles. In this situation, quantum features such as entanglement contribute to enhancing the precision of quantum sensors beyond the capacity of…

The theory of quantum Brownian motion describes the properties of a large class of open quantum systems. Nonetheless, its description in terms of a Born-Markov master equation, widely used in the literature, is known to violate the…

Quantum Physics · Physics 2016-12-16 Aniello Lampo , Soon Hoe Lim , Jan Wehr , Pietro Massignan , Maciej Lewenstein

The logarithm-determinant is an widely-present operation in many areas of physics and computer science. Derivatives of the logarithm-determinant compute physically relevant quantities in statistical physics models, quantum field theories,…

Quantum Physics · Physics 2025-09-23 Thomas E. Baker , Jaimie A. Greasley

Given the recent developments in quantum techniques, modeling the physical Hamiltonian of a target quantum many-body system is becoming an increasingly practical and vital research direction. Here, we propose an efficient strategy combining…

Quantum Physics · Physics 2023-06-26 Tian-Lun Zhao , Shi-Xin Hu , Yi Zhang

A simple model of quantum particle is proposed in which the particle in a {\it macroscopic} rest frame is represented by a {\it microscopic d}-dimensional oscillator, {\it s=(d-1)/2} being the spin of the particle. The state vectors are…

Quantum Physics · Physics 2007-05-23 Blagowest Nikolov

We investigate the role of a statistical complexity measure to assign equilibration in isolated quantum systems. While unitary dynamics preserve global purity, expectation values of observables often exhibit equilibration-like behavior,…

Quantum Physics · Physics 2025-08-14 Marcos G. Alpino , Tiago Debarba , Reinaldo O. Vianna , André T. Cesário

A model master equation suitable for quantum computing dynamics is presented. In an ideal quantum computer (QC), a system of qubits evolves in time unitarily and, by virtue of their entanglement, interfere quantum mechanically to solve…

Quantum Physics · Physics 2017-05-31 Frank Tabakin

We analytically derive the exact -- though formal -- master equation for a two-level quantum system (qubit) interacting with a bosonic environment within the rotating-wave approximation, assuming the environment is initially in an arbitrary…

Quantum Physics · Physics 2025-10-16 Hiromichi Nakazato , Saverio Pascazio

Quantum sensors can show unprecedented sensitivities, provided they are controlled in a very specific, optimal way. Here, we consider a spin sensor of time-varying fields in the presence of dephasing noise, and we show that the problem of…

Quantum Physics · Physics 2024-07-10 S. Hernández-Gómez , F. Balducci , G. Fasiolo , P. Cappellaro , N. Fabbri , A. Scardicchio

An arbitrary operator corresponding to a physical observable cannot be measured in a single measurement on currently available quantum hardware. To obtain the expectation value of the observable, one needs to partition its operator to…

Quantum Physics · Physics 2021-12-07 Tzu-Ching Yen , Artur F. Izmaylov

Ever since the formulation of quantum mechanics, there is very little understanding of the process of the collapse of a wavefunction. We have proposed a dynamical model to emulate the measurement postulates of quantum mechanics. We…

Quantum Physics · Physics 2023-08-16 Gurpahul Singh , Ritesh K. Singh , Soumitro Banerjee