# On work and heat in time-dependent strong coupling

Tutkimustuotos: Lehtiartikkeli › › vertaisarvioitu

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**On work and heat in time-dependent strong coupling.** / Aurell, Erik.

Tutkimustuotos: Lehtiartikkeli › › vertaisarvioitu

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*Entropy*, Vuosikerta. 19, Nro 11, 595, Sivut 1-17. https://doi.org/10.3390/e19110595

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*Entropy*,

*19*(11), 1-17. [595]. https://doi.org/10.3390/e19110595

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TY - JOUR

T1 - On work and heat in time-dependent strong coupling

AU - Aurell, Erik

PY - 2017/11/1

Y1 - 2017/11/1

N2 - This paper revisits the classical problem of representing a thermal bath interacting with a system as a large collection of harmonic oscillators initially in thermal equilibrium. As is well known, the system then obeys an equation, which in the bulk and in the suitable limit tends to the Kramers-Langevin equation of physical kinetics. I consider time-dependent system-bath coupling and show that this leads to an additional harmonic force acting on the system. When the coupling is switched on and switched off rapidly, the force has delta-function support at the initial and final time. I further show that the work and heat functionals as recently defined in stochastic thermodynamics at strong coupling contain additional terms depending on the time derivative of the system-bath coupling. I discuss these terms and show that while they can be very large if the system-bath coupling changes quickly, they only give a finite contribution to the work that enters in Jarzynski's equality. I also discuss that these corrections to standard work and heat functionals provide an explanation for non-standard terms in the change of the von Neumann entropy of a quantum bath interacting with a quantum system found in an earlier contribution (Aurell and Eichhorn, 2015).

AB - This paper revisits the classical problem of representing a thermal bath interacting with a system as a large collection of harmonic oscillators initially in thermal equilibrium. As is well known, the system then obeys an equation, which in the bulk and in the suitable limit tends to the Kramers-Langevin equation of physical kinetics. I consider time-dependent system-bath coupling and show that this leads to an additional harmonic force acting on the system. When the coupling is switched on and switched off rapidly, the force has delta-function support at the initial and final time. I further show that the work and heat functionals as recently defined in stochastic thermodynamics at strong coupling contain additional terms depending on the time derivative of the system-bath coupling. I discuss these terms and show that while they can be very large if the system-bath coupling changes quickly, they only give a finite contribution to the work that enters in Jarzynski's equality. I also discuss that these corrections to standard work and heat functionals provide an explanation for non-standard terms in the change of the von Neumann entropy of a quantum bath interacting with a quantum system found in an earlier contribution (Aurell and Eichhorn, 2015).

KW - Quantum-classical correspondence for heat

KW - Stochastic thermodynamics

KW - Strong coupling

KW - Zwanzig model

UR - http://www.scopus.com/inward/record.url?scp=85034232309&partnerID=8YFLogxK

U2 - 10.3390/e19110595

DO - 10.3390/e19110595

M3 - Article

AN - SCOPUS:85034232309

VL - 19

SP - 1

EP - 17

JO - Entropy

JF - Entropy

SN - 1099-4300

IS - 11

M1 - 595

ER -

ID: 16605576