Enhanced cooling for stronger qubit-phonon couplings

TL;DR

This paper investigates how going beyond the secular approximation affects quantum cooling in a laser-driven quantum dot embedded in a phononic nano-cavity, revealing the importance of fast oscillating terms in strong QD-phonon coupling regimes.

Contribution

It provides an analytical estimate of the impact of non-secular terms on quantum cooling dynamics in a QD-phonon system beyond the secular approximation.

Findings

Fast oscillating terms significantly influence cooling efficiency.

Quantum cooling behavior differs when including non-secular effects.

Steady-state phonon statistics reveal altered cooling dynamics.

Abstract

Here we present details on how the cooling effects of an opto-mechanical system are affected beyond the secular approximation. To this end, a laser driven two-level quantum dot (QD) embed- ded in a phononic nano-cavity is investigated for moderately strong QD-phonon couplings regimes. For these regimes, the use of a secular approximation within the QD-phonon interaction terms is no longer justified as the rapidly oscillating terms cannot be neglected from the system dynamics. Therefore, one shows that although being small, their contribution plays an important role when quantum cooling is achieved. The main contribution of the fast oscillating terms is analytically estimated and one compares how the quantum cooling dynamics change within or beyond the sec- ular approximation. The behavior of the quantum cooling effect is investigated in the steady-state regime via the phonon field statistics.