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Quantum phase transitions (QPTs) in the spin-boson model with/without the rotating-wave approximation (RWA) are systematically investigated through variational calculations using a sub-Ohmic bath with high spectral density. Four cases…

Quantum Physics · Physics 2026-03-17 Nengji Zhou , Yulong Shen , Zhe Sun

The uncertainty quantifications of theoretical results are of great importance to make meaningful comparisons of those results with experimental data and to make predictions in experimentally unknown regions. By quantifying uncertainties,…

Nuclear Theory · Physics 2018-12-10 Sota Yoshida , Noritaka Shimizu , Tomoaki Togashi , Takaharu Otsuka

We study the low energy states of finite spin chains with isotropic (Heisenberg) and anisotropic (XY and Ising-like) exchange interaction with uniform and non-uniform coupling constants. We show that for an odd number of sites a spin…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Florian Meier , Jeremy Levy , Daniel Loss

Phase transitions which occur at zero temperature when some non-thermal parameter like pressure, chemical composition or magnetic field is changed are called quantum phase transitions. They are caused by quantum fluctuations which are a…

Statistical Mechanics · Physics 2007-05-23 Thomas Vojta

In this work, we propose a theory of temperature estimation of quantum systems, which is applicable in the regime of non-negligible prior temperature uncertainty and limited measurement data. In this regime the problem of establishing a…

We propose that proximity of the first-order transition manifested by the quantum tricritical point (QTCP) explains non-Fermi-liquid properties of YbRh2Si2. Here, at the QTCP, a continuous phase transition changes into first order at zero…

Strongly Correlated Electrons · Physics 2008-11-06 Takahiro Misawa , Youhei Yamaji , Masatoshi Imada

We propose a thermodynamic multi-state spin model in order to describe equilibrial behavior of a society. Our model is inspired by the Axelrod model used in social network studies. In the framework of the statistical mechanics language, we…

Physics and Society · Physics 2015-01-09 Jozef Genzor , Vladimir Buzek , Andrej Gendiar

Uncertainty relations represent a foundational principle in quantum mechanics, imposing inherent limits on the precision with which \textit{mechanically} conjugate variables such as position and momentum can be simultaneously determined.…

Quantum Physics · Physics 2025-11-10 Ye-Ming Meng , Zhe-Yu Shi

We derive a thermodynamic uncertainty relation for first passage processes in quantum Markov chains. We consider first passage processes that stop after a fixed number of jumps, which contrasts with typical quantum Markov chains which end…

Quantum Physics · Physics 2022-04-21 Yoshihiko Hasegawa

Quantum correlations including entanglement and quantum discord has drawn much attention in characterizing quantum phase transitions. Quantum deficit originates in questions regarding work extraction from quantum systems coupled to a heat…

Quantum Physics · Physics 2017-11-22 Yao-Kun Wang

Conventional criticality-based quantum metrological schemes work only at zero or very low temperature because the quantum uncertainty around the quantum phase-transition point is generally erased by thermal fluctuations with the increase of…

Quantum Physics · Physics 2021-10-18 Wei Wu , Chuan Shi

Several prominent proposals have suggested that spins of localized electrons could serve as quantum computer qubits. The exchange interaction has been invoked as a means of implementing two qubit gates. In this paper, we analyze the…

Strongly Correlated Electrons · Physics 2016-08-31 Ari Mizel , Daniel A. Lidar

The magnetic insulator copper pyrazine dinitrate comprises antiferromagnetic spin-1/2 chains that are well described by the exactly solvable one-dimensional Heisenberg model, providing a unique opportunity for a quantitative comparison…

Strongly Correlated Electrons · Physics 2018-01-04 Oliver Breunig , Markus Garst , Andreas Klümper , Jens Rohrkamp , Mark M. Turnbull , Thomas Lorenz

We investigate the thermal quantum and total correlations in the anisotropic XY spin chain in transverse field. While we adopt concurrence and geometric quantum discord to measure quantum correlations, we use measurement-induced nonlocality…

Quantum Physics · Physics 2012-11-16 B. Çakmak , G. Karpat , Z. Gedik

Quantum Fisher information (QFI) and skew information (SI) plays a key role in the quantum resource theory. Understanding these measures in the physical system has practical significance in the state parameter estimation and quantum…

Quantum Physics · Physics 2021-11-17 R. Muthuganesan , V. K. Chandrasekar

Recently has been observed for some one-dimensional models that exhibit unexpected pseudo-transitions and quasi-phases. This pseudo-transition resembles a first- and second-order phase transition simultaneously. One of those models is the…

Strongly Correlated Electrons · Physics 2018-06-18 I. M. Carvalho , J. Torrico , S. M. de Souza , M. Rojas , O. Rojas

The quantum critical regime marks a zone in the phase diagram where quantum fluctuation around the critical point plays a significant role at finite temperatures. While it is of great physical interest, simulation of the quantum critical…

Quantum Physics · Physics 2023-08-09 Zhi-Quan Shi , Xu-Dan Xie , Dan-Bo Zhang

The quantum Cram\'er-Rao bound sets a fundamental limit on the accuracy of unbiased parameter estimation in quantum systems, relating the uncertainty in determining a parameter to the inverse of the quantum Fisher information. We…

The theory of deconfined quantum critical points describes phase transitions at temperature T = 0 outside the standard paradigm, predicting continuous transformations between certain ordered states where conventional theory requires…

Strongly Correlated Electrons · Physics 2016-04-28 Hui Shao , Wenan Guo , Anders W. Sandvik

We study the ground-state properties of a spin-1/2 model on a chain containing four-spin Ising-like interactions in the presence of both transverse and longitudinal magnetic fields. We use entanglement entropy and finite-size scaling…

Statistical Mechanics · Physics 2015-06-22 B. Boechat , J. Florencio , A. Saguia , O. F. de Alcantara Bonfim