A polaron theory of quantum thermal transistor in nonequilibrium three-level systems

Abstract

We investigate the quantum thermal transistor effect in nonequilibrium three-level systems by applying the polaron transformed Redfield equation combined with full counting statistics. The steady state heat currents are obtained via this unified approach over a wide region of system-bath coupling, and can be analytically reduced to the Redfield and nonequilibrium noninteracting blip approximation results in the weak and strong coupling limits, respectively. A giant heat amplification phenomenon emerges in the strong system-bath coupling limit, where transitions mediated by the middle thermal bath is found to be crucial to unravel the underlying mechanism. Moreover, the heat amplification is also exhibited with moderate coupling strength, which can be properly explained within the polaron framework.

Quantum thermal transistor: a unified method from weak to strong internal coupling

“…The thermal transistor was initially proposed by Li and coworkers [24] in nonlinear lattices. Later, fully quantum thermal transistors based on qubit-qubit [30,31], qubit-qutrit [32], qubit-qubit-qubit [33] coupling and three-level system [29,34] are proposed. Especially, Yu et al propose a multifunctional quantum thermal device based on XXX-type internal interaction [33], which can work as a thermal transistor, a switcher, a valve, and even a thermal recti er.…”

“…Especially, Yu et al propose a multifunctional quantum thermal device based on XXX-type internal interaction [33], which can work as a thermal transistor, a switcher, a valve, and even a thermal recti er. Wang et al investigate the quantum thermal transistor effect in nonequilibrium three-level systems over a wide region of systembath coupling [34].…”

“…Especially, Scarani et al nd that the coarse-graining master equation is valid across all internal coupling strengths [42]. If the weak system-bath coupling approximation is not held, a polaron theory can be applied [27,34,43].…”

Quantum thermal transistors: Operation characteristics in steady state versus transient regimes

“…A QTT using supercon-ducting circuits is designed in [68], where this device is said to have properties similar to the conventional semiconductor transistor. A QTT with a giant heat amplification phenomenon in presence of strong system-bath coupling limit by applying the polaron transformed Redfield equation combined with full counting statistics is investigated in [69].…”