Angle-dependent quantum Otto heat engine based on coherent dipole-dipole coupling

Abstract

Electromagnetic interactions between molecules or within a molecule have been widely observed in biological systems and exhibit broad application for molecular structural studies. Quantum delocalization of molecular dipole moments has inspired researchers to explore new avenues to utilize this physical effect for energy harvesting devices. Herein, we propose a simple model of the angle-dependent quantum Otto heat engine which seeks to facilitate the conversion of heat to work. Unlike previous studies, the adiabatic processes are accomplished by varying only the directions of the magnetic field. We show that the heat engine continues to generate power when the angle relative to the vector r joining the centres of coupled dipoles departs from the magic angle θm where the static coupling vanishes. A significant improvement in the device performance has to be attributed to the presence of the quantum delocalized levels associated with the coherent dipole-dipole coupling. These results obtained may provide a promising model for the biomimetic design and fabrication of quantum energy generators.

Magnetic Engine for the Single-Particle Landau Problem

“…The last equation corresponds to the microscopic formulation of the first law of thermodynamics [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][25][26][27]31,34,35]. The first term in Equation (10) is associated with the energy exchange, while the second term represents the work done.…”

“…The possibility to create an alternative and efficient nanoscale device, like its macroscopic counterpart, introduces the concept of the quantum engine, which was proposed by Scovil and Schultz-Dubois in the 1950s [1]. The key point here is the quantum nature of the working substance and of course the quantum versions of the laws of thermodynamics [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The combination of these two simple facts leads to very interesting studies of well-known macroscopic engines of thermodynamics, such as Carnot, Stirling and Otto, among others [2][3][4].…”

Magnetic Quantum Otto Engine for the Single-Particle Landau Problem

“…The first law of quantum thermodynamics is fully addressed in many works [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and gives us the possibility to explore different quantum cycles and compare them with the classical analogues. To derivate this law simply, consider a Hamiltonian with an explicit dependence of some parameter that we will call µ in a generic form [25].…”

“…This case has been considered in several works for differenst quantum systems [3,9,13,24,27] where the key findings are an expression for the efficiency present in Eq. (11) and establishing the value of γ for that case.…”

“…The key point here is the quantum nature of the working substance and of course the quantum versions of the laws of thermodynamics [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The combination of these two simple facts leads to very interesting studies of well-known macroscopic engines of thermodynamics, such as Carnot, Stirling and Otto, among others [2][3][4]. The maximum efficiency of these engines is governed by the Carnot efficiency, and this cannot be surpassed unless the reservoirs are also of a quantum nature, for example, modeled as quantum coherent states or squeezed thermal states [4][5][6].…”