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An exactly solvable model for a quantum measurement is discussed, that integrates quantum measurements with classical measurements. The z-component of a spin-1/2 test spin is measured with an apparatus, that itself consists of magnet of N…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 A. E. Allahverdyan , R. Balian , Th. M. Nieuwenhuizen

In this manuscript, we analyze the mechanism of the superradiant phase transition in the anisotropic Rabi model under the classical oscillator limit using the pattern picture. By expanding the anisotropic Rabi model Hamiltonian in operator…

Quantum Physics · Physics 2026-05-07 Yuan Qiu , Ke-Xiong Yan , Jun-Hao Lin , Jie Song , Ye-Hong Chen , Yan-Xia

We consider a disordered quantum metamaterial formed by an array of superconducting flux qubits coupled to microwave photons in a cavity. We map the system on the Tavis-Cummings model accounting for the disorder in frequencies of the…

Superconductivity · Physics 2015-07-08 Dmitriy S. Shapiro , Pascal Macha , Alexey N. Rubtsov , Alexey V. Ustinov

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

Implementing fast and high-fidelity quantum operations using open-loop quantum optimal control relies on having an accurate model of the quantum dynamics. Any deviations between this model and the complete dynamics of the device, such as…

Quantum Physics · Physics 2024-10-31 Elie Genois , Noah J. Stevenson , Noah Goss , Irfan Siddiqi , Alexandre Blais

A calorimetric measurement has recently been proposed as a promising technique to measure thermodynamic quantities in a dissipative superconducting qubit. These measurements rely on the fact that the system is projected into energy…

Quantum Physics · Physics 2016-12-28 Rui Sampaio , Samu Suomela , Tapio Ala-Nissila

We describe the quantum phase transitions in the ferromagnetic Dicke-Ising model using a Landau theory approach. The theory quantitatively captures the change from a second- to a first-order transition between the normal and superradiant…

Strongly Correlated Electrons · Physics 2026-05-28 Jan Alexander Koziol

Collective bosonic excitations are a fascinating aspect of broken-symmetry correlated phases. A wealth of such phases emerged in tailored moir\'e heterostructures, where, in addition, new direct knobs of control exist. Our work explores how…

Strongly Correlated Electrons · Physics 2026-03-13 Gal Shavit , Gil Refael

We face the problem of detecting and featuring footprints of quantum criticality in the finite-temperature behavior of quantum many-body systems. Our strategy is that of comparing the phase diagram of a system displaying a T=0 quantum phase…

Statistical Mechanics · Physics 2007-08-09 Alessandro Cuccoli , Alessio Taiti , Ruggero Vaia , Paola Verrucchi

A cavity quantum electrodynamical scenario is proposed for implementing a Schr\"odinger microscope capable of amplifying differences between non orthogonal atomic quantum states. The scheme involves an ensemble of identically prepared…

Quantum criticality is the intriguing possibility offered by the laws of quantum mechanics when the wave function of a many-particle physical system is forced to evolve continuously between two distinct, competing ground states. This…

Mesoscale and Nanoscale Physics · Physics 2008-09-18 Nicolas Roch , Serge Florens , Vincent Bouchiat , Wolfgang Wernsdorfer , Franck Balestro

Quantum state tomography (QST) is essential for validating quantum devices but suffers from exponential scaling in system size. Neural-network quantum states, such as Restricted Boltzmann Machines (RBMs), can efficiently parameterize…

Quantum Physics · Physics 2026-01-30 Simon Tonner , Viet T. Tran , Richard Kueng

An open fully connected system of qubits at nonzero temperature is driven within a finite time interval along various paths in the space of its control parameters. The driving leads across finite-size precursors of first- and second-order…

Quantum Physics · Physics 2024-12-18 Felipe Matus , Pavel Cejnar

We investigate the magnetic quantum phase-transitions in bulk correlated metals at the level of dynamical mean-field theory. To this end, we focus on the Hubbard model on a simple cubic lattice as a function of temperature and electronic…

Strongly Correlated Electrons · Physics 2024-09-09 S. Adler , D. R. Fus , M. O. Malcolms , A. Vock , K. Held , A. A. Katanin , T. Schäfer , A. Toschi

Electromagnetic modes are instrumental in building quantum machines. In this experiment, we introduce a method to manipulate these modes by effectively controlling their phase space. Preventing access to a single energy level, corresponding…

In this paper, we discuss a geometrodynamical approach to particle physics, in which quantum mechanics is no more than an approximated model of nature in the microscopic scale. We derive quantum mechanics from the concept of non-local…

General Relativity and Quantum Cosmology · Physics 2020-02-05 Tomer Shushi

We adopt a three-level bosonic model to investigate the quantum phase transition in an ultracold atom-molecule conversion system which includes one atomic mode and two molecular modes. Through thoroughly exploring the properties of energy…

Quantum Physics · Physics 2013-07-12 Sheng-Chang Li , Li-Bin Fu , Fu-Li Li

In this review, we study some aspects of the non-equilibrium dynamics of quantum systems. In particular, we consider the effect of varying a parameter in the Hamiltonian of a quantum system which takes it across a quantum critical point or…

Statistical Mechanics · Physics 2015-05-14 Shreyoshi Mondal , Diptiman Sen , K. Sengupta

A one-dimensional quantum oscillator is monitored by taking repeated position measurements. As a first con- tribution, it is shown that, under a quantum nondemolition measurement scheme applied to a system initially at the ground state, (i)…

Quantum Physics · Physics 2015-11-13 Vincenzo Matta , Vincenzo Pierro

Quantum physics enables parameter estimation with precisions beyond the capability of classical sensors. Quantum criticality is a key resource for this quantum-enhanced sensing, but experimental realization has been challenging due to the…

Quantum Physics · Physics 2026-02-10 Lei Xiao , Saubhik Sarkar , Kunkun Wang , Abolfazl Bayat , Peng Xue