Quantum heat transport in a spin-boson nanojunction: Coherent and incoherent mechanisms

• Published in: Europhysics letters Vol. 107; no. 3; pp. 30003 - p1-30003-p6
• Main Authors: Yang, Yue, Wu, Chang-Qin
• Format: Journal Article
• Language: English
• Published: EDP Sciences, IOP Publishing and Società Italiana di Fisica 01.08.2014
• Subjects: 05.60.Gg; 44.05.+e; 44.10.+i; Coherence; Fermions; Mathematical analysis; Mathematical models; Saturation; Steady state; Transport; Transport processes
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/0295-5075/107/30003

Quantum heat transport in a spin-boson system under nonequilibrium steady state (NESS) is investigated by the nonequilibrium Green's function (NEGF) method. Spin-spin correlators are calculated via the Majorana fermion representation of spin operators, which allows us to make use of Wick's theorem through standard diagrammatic techniques. An analytic formula of heat current is obtained, and numerical results are presented in comparison with those obtained by other methods. Two types of transport mechanisms are identified in high- and low-temperature regions, respectively, which shows a transition from incoherent to coherent transport process with the baths' temperatures decreased. Additionally, a saturation of the heat current is confirmed when increasing the coupling strength between the baths and the intermediate system, which is a sign of quantum Zeno effect (QZE) in the transport process.