2016/09/30 by Akihito Kato, Yoshitaka Tanimura · 3 citations
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Context (archaeology) #Coupling (piping) #Heat current #Heat engine #Quantum #Quantum many-body systems #Quantum master equation #Quantum system #Thermal reservoir #Work (physics) #cond-mat.stat-mech #quant-ph #stochastic dynamics and bifurcation
paper · pdf · doi:10.1063/1.4971370
published as Journal of Chemical Physics 145, 224105 (2016) · 10 pages, 6 figures, updated in the published version
openalex created_date 2016/10/07 · openalex publication_date 2016/12/13 · arxiv created 2017/11/02 · arxiv updated 2017/11/03 · openalex updated_date 2026/08/05
We consider a quantum system strongly coupled to multiple heat baths at different temperatures. Quantum heat transport phenomena in this system are investigated using two definitions of the heat current: one in terms of the system energy and the other in terms of the bath energy. When we consider correlations among system-bath interactions (CASBIs)-which have a purely quantum mechanical origin-the definition in terms of the bath energy becomes different. We found that CASBIs are necessary to maintain the consistency of the heat current with thermodynamic laws in the case of strong system-bath coupling. However, within the context of the quantum master equation approach, both of these definitions are identical. Through a numerical investigation, we demonstrate this point for a non-equilibrium spin-boson model and a three-level heat engine model using the reduced hierarchal equations of motion approach under the strongly coupled and non-Markovian conditions. We observe the cyclic behavior of the heat currents and the work performed by the heat engine, and we find that their phases depend on the system-bath coupling strength. Through consideration of the bath heat current, we show that the efficiency of the heat engine decreases as the strength of the system-bath coupling increases, due to the CASBI contribution. In the case of a large system-bath coupling, the efficiency decreases further if the bath temperature is increased, even if the ratio of the bath temperatures is fixed, due to the discretized nature of energy eigenstates. This is also considered to be a unique feature of quantum heat engines.