A sparcely confined water molecules undergoing finite-time thermodynamic processes

TL;DR

This paper investigates finite-time thermodynamic processes in a weakly interacting, sparsely confined water molecule system under electric fields, analyzing non-equilibrium states, work distributions, and thermodynamic quantities.

Contribution

It introduces a model of water molecules under electric fields undergoing finite-time protocols, deriving thermodynamic quantities and work distributions from non-equilibrium data.

Findings

Extraction of equilibrium free energy from non-equilibrium processes

Work distribution analysis in a three-level quantum system

Dependence of average work on frequency and time

Abstract

A large number of water molecules are each placed on a lattice far apart so that they are very weakly interacting with each other and in contact with a heat bath at temperature $T$. A strong static electric field, $E_{0}$, is applied to these molecules along a $z$-axis causing three level split energy values. A weak AC electric field that acts for a finite time $\tau$ applied in the $xy-$plane induces transitions between the three levels. This weak AC field acts as a protocol $\zeta(t)$, that is switched on at $t=0$ and switched off at $t=\tau$. Through this protocol, the system is taken from an initial thermodynamic equilibrium state $F(T,0)$ to the non-equilibrium state $F_{non-equil}(T, \tau)$ recorded right when the AC field is switched off at time $t=\tau$. Once again the AC field is switched on and let it act for the same finite amount of time $\tau$ and its non-equilibrium state $F_{non-equil}(T, \tau)$ recorded right when the AC field is switched off. The same cyclic process is repeated for a large number of times. The data available for this finite-time non-equilibrium process allowed us to extract equilibrium thermodynamic quantities like free energy, which is what we call Jarznski equality and its relation to the second law of thermodynamics. The work distributions of the three-level system in the optimum condition is obtained. Besides, the average work of the system as a function of $\omega$ and time around the optimum frequency are evaluated, where $\omega$ is the frequency of the AC electric field.