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It is "conventional wisdom" that the uncertainty of local temperature measurements on equilibrium systems diverges exponentially fast as their temperature $T$ drops to zero. In contrast, some exactly solvable models showcase a more benign…

Quantum Physics · Physics 2018-07-04 Karen V. Hovhannisyan , Luis A. Correa

The last decade has witnessed the remarkable progress in our understanding of thermalization in isolated quantum systems. Combining the eigenstate thermalization hypothesis with quantum measurement theory, we extend the framework of quantum…

Statistical Mechanics · Physics 2018-10-31 Yuto Ashida , Keiji Saito , Masahito Ueda

Thermometry is a fundamental parameter estimation problem which is crucial in the development process of natural sciences. One way to solve this problem is to the extensive used local thermometry theory, which makes use of the classical and…

Quantum Physics · Physics 2023-05-16 Shoukang Chang , Wei Ye , Xuan Rao , Huan Zhang , Liqing Huang , Mengmeng Luo , Yuetao Chen , Qiang Ma , Shaoyan Gao

On a quantum superconducting processor we observe partial and infinite-temperature thermalization induced by a sequence of repeated quantum projective measurements, interspersed by a unitary (Hamiltonian) evolution. Specifically, on a qubit…

Quantum Physics · Physics 2023-06-22 Alessandro Santini , Andrea Solfanelli , Stefano Gherardini , Guido Giachetti

We propose a quantum information based scheme to reduce the temperature of quantum many-body systems, and access regimes beyond the current capability of conventional cooling techniques. We show that collective measurements on multiple…

Ultra-cold atoms in optical lattices provide one of the most promising platforms for analog quantum simulations of complex quantum many-body systems. Large-size systems can now routinely be reached and are already used to probe a large…

Quantum Gases · Physics 2016-11-30 J. Gertis , M. Friesdorf , C. A. Riofrio , J. Eisert

Quantum fidelity is a measure to quantify the closeness of two quantum states. In an operational sense, it is defined as the minimal overlap between the probability distributions of measurement outcomes and the minimum is taken over all…

Quantum Physics · Physics 2019-07-24 Changhun Oh , Changhyoup Lee , Leonardo Banchi , Su-Yong Lee , Carsten Rockstuhl , Hyunseok Jeong

Temperature is a deceptively simple concept that still raises deep questions at the forefront of quantum physics research. The observation of thermalisation in completely isolated quantum systems, such as cold-atom quantum simulators,…

Quantum Physics · Physics 2022-03-09 Mark T. Mitchison , Archak Purkayastha , Marlon Brenes , Alessandro Silva , John Goold

The ultimate precision of any measurement of the temperature of a quantum system is the inverse of the local quantum thermal susceptibility [De Pasquale et al., Nature Communications 7, 12782 (2016)] of the subsystem with whom the…

Quantum Physics · Physics 2017-05-24 Giacomo De Palma , Antonella De Pasquale , Vittorio Giovannetti

Relativistic quantum metrology provides an optimal strategy for the estimation of parameters encoded in quantum fields in flat and curved spacetime. These parameters usually correspond to physical quantities of interest such as proper…

Quantum Physics · Physics 2017-05-25 Dominik Šafránek , Jan Kohlrus , David Edward Bruschi , Antony R. Lee , Ivette Fuentes

Quantum simulation is a highly ambitious program in cold atom research currently being pursued in laboratories worldwide. The goal is to use cold atoms in optical lattice to simulate models for unsolved strongly correlated systems, so as to…

Quantum Gases · Physics 2015-05-14 Qi Zhou , Tin-Lun Ho

One of the fundamental problems of quantum statistical physics is how an ideally isolated quantum system can ever reach thermal equilibrium behavior despite the unitary time evolution of quantum-mechanical systems. Here, we study, via…

Quantum Physics · Physics 2025-06-24 Marvin Lenk , Sayak Biswas , Anna Posazhennikova , Johann Kroha

We propose observable bounds for Gaussian illumination to maximize the signal-to-noise ratio, which minimizes the discrimination error between the presence and absence of a low-reflectivity target using Gaussian states. The observable…

We assess precision thermometry for an arbitrary single quantum system. For a $d$-dimensional harmonic system we show that the gap sets a single temperature that can be optimally estimated. Furthermore, we establish a simple linear…

Quantum Physics · Physics 2018-02-06 Steve Campbell , Marco G. Genoni , Sebastian Deffner

Precise thermometry is of wide importance in science and technology in general and in quantum systems in particular. Here, we investigate fundamental precision limits for thermometry on cold quantum systems, taking into account constraints…

Quantum Physics · Physics 2020-10-02 Mathias R. Jørgensen , Patrick P. Potts , Matteo G. A. Paris , Jonatan B. Brask

Proofs of the quantum advantage available in imaging or detecting objects under quantum illumination can rely on optimal measurements without specifying what they are. We use the continuous-variable Gaussian quantum information formalism to…

Quantum Physics · Physics 2021-03-04 Hao Yang , Wojciech Roga , Jonathan D. Pritchard , John Jeffers

The precise knowledge of the temperature of an ultracold lattice gas simulating a strongly correlated system is a question of both, fundamental and technological importance. Here, we address such question by combining tools from quantum…

Quantum Physics · Physics 2015-09-08 Mohammad Mehboudi , Maria Moreno-Cardoner , Gabriele De Chiara , Anna Sanpera

Quantum Gaussian states can be considered as the majority of the practical quantum states used in quantum communications and more generally in quantum information. Here we consider their properties in relation with the geometrically uniform…

Quantum Physics · Physics 2014-10-21 Gianfranco Cariolaro , Roberto Corvaja , Gianfranco Pierobon

Especially investigated in recent years, the Gaussian discord can be quantified by a distance between a given two-mode Gaussian state and the set of all the zero-discord two-mode Gaussian states. However, as this set consists only of…

Quantum Physics · Physics 2015-06-22 Paulina Marian , Tudor A. Marian

While the ability to measure low temperatures accurately in quantum systems is important in a wide range of experiments, the possibilities and the fundamental limits of quantum thermometry are not yet fully understood theoretically. Here we…

Quantum Physics · Physics 2019-07-10 Patrick P. Potts , Jonatan Bohr Brask , Nicolas Brunner