scholarly journals Quantum batteries at the verge of a phase transition

2021 ◽  
Author(s):  
Felipe Barra ◽  
Karen Hovhannisyan ◽  
Alberto Imparato
Keyword(s):  
Phase Transition ◽  
Phase Transition Point ◽  
Thermodynamic Efficiency ◽  
Ising Chain ◽  
Battery Charger ◽  
Coupling Term ◽  
Strongly Coupled ◽  
Single Spin ◽  
Quantum Device ◽  
Reduced State

Abstract Starting from the observation that the reduced state of a system strongly coupled to a bath is, in general, an athermal state, we introduce and study a cyclic battery-charger quantum device that is in thermal equilibrium, or in a ground state, during the charge storing stage. The cycle has four stages: the equilibrium storage stage is interrupted by disconnecting the battery from the charger, then work is extracted from the battery, and then the battery is reconnected with the charger; finally, the system is brought back to equilibrium. At no point during the cycle are the battery-charger correlations artificially erased. We study the case where the battery and charger together comprise a spin-1/2 Ising chain, and show that the main characteristics - the extracted energy and the thermodynamic efficiency - can be enhanced by operating the cycle close to the quantum phase transition point. When the battery is just a single spin, we find that the output work and efficiency show a scaling behavior at criticality and derive the corresponding critical exponents. Due to always present correlations between the battery and the charger, operations that are equivalent from the perspective of the battery can entail different energetic costs for switching the battery-charger coupling. This happens only when the coupling term does not commute with the battery's bare Hamiltonian, and we use this purely quantum leverage to further optimize the performance of the device.

THE FINITE-SIZE EFFECT ON THE ENTANGLEMENT OF THE QUANTUM ISING CHAIN

2004 ◽  
Vol 18 (17n19) ◽  
pp. 2564-2568 ◽  
Author(s):  
LIFA ZHANG ◽  
PEIQING TONG
Keyword(s):  
Phase Transition ◽  
Quantum Phase Transition ◽  
Spin Chain ◽  
Transition Point ◽  
Nearest Neighbor ◽  
Finite Size ◽  
Phase Transition Point ◽  
Finite Size Effect ◽  
Ising Chain ◽  
Derivatives Of

By using the concurrence, the entanglement of a quantum Ising chain is studied numerically. It is found that there is a gap in the concurrence of the nearest-neighbor spins at the quantum phase transition point for the chain with even spins. The gap disappears as the number of the spins goes to infinite. Except for the critical point, the derivatives of the concurrence display the similar scaling behavior as that of the odd-spin chain.

scholarly journals Gluodynamics and deconfinement phase transition under rotation from holography

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Xun Chen ◽  
Lin Zhang ◽  
Danning Li ◽  
Defu Hou ◽  
Mei Huang
Keyword(s):  
Phase Transition ◽  
Angular Velocity ◽  
Chemical Potential ◽  
Entropy Density ◽  
Thermodynamic Quantities ◽  
Strongly Coupled ◽  
Trace Anomaly ◽  
Holographic Qcd ◽  
Deconfinement Phase Transition ◽  
Small Chemical

Abstract We investigate rotating effect on deconfinement phase transition in an Einstein-Maxwell-Dilaton (EMD) model in bottom-up holographic QCD approach. By constructing a rotating black hole, which is supposed to be dual to rotating strongly coupled nuclear matter, we investigate the thermodynamic quantities, including entropy density, pressure, energy density, trace anomaly, sound speed and specific heat for both pure gluon system and two-flavor system under rotation. It is shown that those thermodynamic quantities would be enhanced by large angular velocity. Also, we extract the information of phase transition from those thermodynamic quantities, as well as the order parameter of deconfinement phase transition, i.e. the loop operators. It is shown that, in the T − ω plane, for two-flavor case with small chemical potential, the phase transition is always crossover. The transition temperature decreases slowly with angular velocity and chemical potential. For pure gluon system with zero chemical potential, the phase transition is always first order, while at finite chemical potential a critical end point (CEP) will present in the T − ω plane.

scholarly journals Распространение поверхностной магнитоупругой волны в ферромагнетике в области ориентационного фазового перехода

2020 ◽  
Vol 62 (6) ◽  
pp. 851
Author(s):  
И.В. Мальцев ◽  
И.В. Бычков ◽  
Д.А. Кузьмин ◽  
В.Г. Шавров
Keyword(s):  
Phase Transition ◽  
Group Velocity ◽  
Yttrium Iron Garnet ◽  
Transition Point ◽  
Phase Transition Point ◽  
Yttrium Iron ◽  
Orientational Phase Transition ◽  
Velocity Changes ◽  
Iron Garnet ◽  
Magnetoelastic Surface

In this paper, we have studied the dependencies of group velocity and damping of magnetoelastic surface waves on the frequency at various external magnetic fields and propagation angles. The group velocity spikes occur at frequencies at which the damping peaks of the surface wave are detected. The behavior of a surface magnetoelastic wave in the vicinity of the orientational phase transition was also investigated. At the phase transition point, the group velocity changes by 1%. Dependences of the damping along the surface at various propagation angles point out on the nonreciprocal nature of the wave. All dependencies in this work were obtained using computer modeling. The parameters of the ferromagnet are taken typical for yttrium-iron garnet.

Dielectric lossbs near the phase transition point in DTGSel crystal

1989 ◽  
Vol 10 (6) ◽  
pp. 167-172
Author(s):  
S. A. Gridnev ◽  
B. N. Prasolov ◽  
O. V. Dybova
Keyword(s):  
Phase Transition ◽  
Transition Point ◽  
Phase Transition Point
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