Transport and Energetic Properties of a Ring of Interacting Spins Coupled to Heat Baths

Abstract

We study the heat and spin transport properties in a ring of interacting spins coupled to heat baths at different temperatures. We show that interactions, by inducing avoided crossings, can be a means to tune both the total heat current flowing between the ring and the baths, and the way it flows through the system. In particular, we recognize three regimes in which the heat current flows clockwise, counterclockwise, and in parallel. The temperature bias between the baths also induces a spin current within the ring, whose direction and magnitude can be tuned by the interaction. Lastly, we show how the ergotropy of the nonequilibrium steady state can increase significantly near the avoided crossings.I.

Proposal of a Computational Approach for Simulating Thermal Bosonic Fields in Phase Space

“…For simplicity, the theory was only applied to the free field case [38], in order to demonstrate the technicalities associated with coupling a different NHC thermostat [44,45] to each field mode. However, this theory is intended for situations where the field is coupled to a spin system [47][48][49][50][51][52][53][54][55][56][57]. In this case, the use of NHC thermostats in the dynamics of the thermal state of the field would make it possible to simulate processes that, to our knowledge, have not been investigated so far.…”

“…In addition to the case when the field is coupled to another system [47][48][49][50][51][52][53][54][55][56][57] there are a number of cases when it is desirable to simulate the dynamics of the thermal field state [27-34] on a computer. To this end, we employ a Nosé-Hoover chain (NHC) thermostat [44,45], which may be theoretically defined in terms of a quasi-Lie bracket [63][64][65][66].…”

“…As will be explained below, this feature can be exploited to simulate the passage from a quantum thermal distribution of the modes to a classical one. The generalization of our formalism to situations where the field is coupled to a spin system [47][48][49][50][51][52][53][54][55][56][57] is left for future work. Such an endeavour could lead to new computational experiments on spin dynamics, which to the best of our knowledge, would be novel.…”

Ефект Потоку Енергії В Одновимірній Спін-1/2 XX Моделі Магнетоелектрика. Метод Множника Лагранжа

“…In modern statistical physics, much attention is paid to the theoretical study of nonequilibrium stationary processes of various nature that take place in various systems and models. In particular, the specific features of nonequilibrium steady states (NESSs) were studied in the framework of the nonequilibrium spinboson model [1,2], the simplified model of a system of noninteracting electrons (a one-dimensional chain of fermions consisting of a central part and two metal thermostats) [2], the electron-hole-photon system [3], the finite quantum system of interacting particles connected to electrodes that are simultaneously thermostats [4], the quantum wire [5], the system in which a quantum dot is placed between a metal and a superconductor or a ferromagnetic contact with opposite polarizations [6], the 𝑋𝑋 chain located in a transverse field and connected to quantum reservoirs with noninteracting spins and different temperatures [7], and the spin models with interactions between the nearest neighbors and the energy [8][9][10][11][12][13][14][15][16][17][18][19][20] or spin [9,[21][22][23][24] current. It should be noted that the main specific feature of NESSs is the presence of a permanent flux of some physical quantity (energy, magnetic moment, charge, and so on).…”

Heat Modulation on Target Thermal Bath via Coherent Auxiliary Bath

“…These non-intuitive physical behaviors have become an apparent challenge to the standard laws of thermodynamics [ 15 , 16 ]. The rapid progress of quantum technologies has allowed us to characterize the quantum machine [ 17 , 18 , 19 , 20 ] and experimentally realized them in various quantum systems [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. With the aid of these controllable quantum platforms (systems), some studies focus on the redefinitions of some concepts, such as work and heat [ 31 , 32 , 33 , 34 ], and the verification and modification of thermodynamics second law [ 35 ] in quantum domain.…”