Exploiting coherence for quantum thermodynamic advantage

Abstract

The introduction of the quantum analogue of a Carnot engine based on a bath comprising of particles with a small amount of coherence initiated an active line of research on the harnessing of different quantum resources for the enhancement of thermal machines beyond the standard reversible limit, with an emphasis on non-thermal baths containing quantum coherence. In our work, we investigate the impact of coherence on the thermodynamic tasks of a collision model which is composed of a system interacting, in the continuous time limit, with a series of coherent ancillas of two baths at different temperatures. Our results show the advantages of utilising coherence as a resource in the operation of the machine, and allows it: (i) to exhibit unconventional behavior such as the appearance of a hybrid refrigerator, capable of simultaneous refrigeration and generation of work, and (ii) to function as an engine or a refrigerator with efficiencies larger than the Carnot bound. Moreover, we find an effective upper bound to the efficiency of the thermal machine operating as an engine in the presence of a coherent reservoir.

Heat transport and rectification via quantum statistical and coherence asymmetries

“…By deriving a general heat flow expression, we identify unreported physical conditions and parameter regimes in which the system works as a quantum thermal rectifier. We also show that weak coherences in the reservoirs [29,30] induce thermal rectification in cases that otherwise would be impossible due to the lack of parametric and quantum statistical asymmetries. Furthermore, at low temperatures, we observe that the thermal conductance of the system vanishes exponentially, but it resembles that of crystals and carbon nanotubes at high temperatures.…”

“…The bath elements in the right bath are in a thermal state, ρ th R , as generally done throughout this work. The master equation describing the dynamics of the central qubit in the present situation is given in the following form [29,30]…”

Quantum advantage in charging cavity and spin batteries by repeated interactions

“…One central aim of the field of quantum thermodynamics is to improve and fuel thermodynamic processes via quantum resources [1][2][3][4]. Promising results include enhancements in cooling [5][6][7][8][9][10][11][12], as well as in the power [13][14][15][16][17][18], efficiency [19][20][21][22][23][24], and reliability [25][26][27][28][29][30][31] of quantum engines compared to their classical counterparts. Yet, it is often debated if the potential gains outweigh the cost of preparing the quantum resources, and whether the same output can be simulated by classical means [32][33][34][35].…”

Collective effects and quantum coherence in dissipative charging of quantum batteries

“…In this paper, we consider different dissipative charging processes [37] and study how collective effects and the presence quantum coherences affect their performance. The dissipative quantum batteries we considered are based on collisional models [40][41][42][43][44][45][46][47][48][49][50][51][52], where the interaction between the battery and the bath is modelled in terms of a repeated interactions scheme [37,41] where many identical non-interacting systems in thermal equilibrium interact sequentially with the battery. This leads to a Markovian evolution that can be described in terms of a Lindblad equation [53].…”