Trapping quantum coherence with a dissipative thermal bath

TL;DR

This paper reveals that quantum coherence can be preserved in a two-level system coupled to a thermal bath under specific conditions, challenging the common belief that dissipation always destroys coherence.

Contribution

It establishes a necessary condition for trapping quantum coherence using a thermal bath, highlighting the role of the Lamb shift and counter-rotating interactions.

Findings

Residue coherence survives at high temperatures if the Lamb shift is negative.

Strong and ultrastrong coupling regimes support coherence trapping.

Counter-rotating interactions are essential for coherence preservation.

Abstract

In the long-time limit, an open quantum system coupled to a dissipative environment is believed to lose its coherence without driving or measurement. Counterintuitively, we provide a necessary condition on trapping the coherence of a two-level system entirely with a thermal bath. Based on a time-local master equation, it is found that the residue coherence survives even under a high-temperature bath as long as the long-time Lamb shift is exactly negative to the system transition frequency. This condition is generally met in the strong and even ultrastrong coupling regime that could be relaxed by increasing the environmental temperature. The counter-rotating interactions between system and bath is indispensable to the residue coherence, whose magnitude is affected by the system initial state and the bath structure.