Subject：Coherent quantum dot heat engine
Speaker：Prof. Jaegon Um
Emcee：Prof. Konstantin Dorfman
Time：10:00am, 14th Nov, 2018
Place：Science Building A814
Abstract：
We investigate a coherent two-level quantum dot system coupled to two reservoirs characterized by the chemical potential and temperature, where the coherence is induced by interaction between system and environment. Using the Lindblad master equation derived from the microscopic Hamiltonian of total system and varying an interference factor phenomenologically introduced in order to control the coherence strength, we find that the steady state of system is identical to the solution of master equation in the incoherent two-level quantum dot system, except for the perfectly coherent case which can be achieved in the degenerated two-level system. It turns out that in the steady state of coherent engine output power can be enhanced in comparison with the incoherent engine while the efficiency defined by the ratio of the output power and input heat is independent of the quantum coherence. We also discuss the efficiency at the maximum power in the coherent and incoherent quantum dot engines.
About the Speaker:
Prof. Jaegon Um obtained his PhD from POSTECH in 2008 with specialization in numerical studies of critical phenomena. Then he worked as a postdoc in PNU, KIAS, Wuerzburg, and SNU. In 2018 he returned to POSTECH. During the period, he started the study of stochastic thermodynamics focusing on information engines. He proposed a model of information engine described by stochastic processes not only for the relaxation, also for the measurement, where whole energetics per engine cycle can be obtained. Recently he investigates a condition for preserving coherence in a steady state engine made of a small quantum system.
