# Phonon-assisted tunnelling in a double quantum dot molecule immersed in a cavity

## TL;DR

This paper investigates phonon-assisted tunnelling effects in a double quantum dot molecule within a cavity, revealing how increased tunnelling rates lead to resonance shifts, spectral coalescence, and potential quantum phase transitions.

## Contribution

It introduces a quantum Markovian master equation approach to analyze phonon-assisted tunnelling effects and identifies exceptional points indicating dynamical phase transitions.

## Key findings

- Higher PhAT rates enhance QD-cavity interactions off-resonance.
- Spectroscopic resolution is lost due to transition energy coalescence.
- Multiple exceptional points suggest quantum dynamical phase transitions.

## Abstract

The effects caused by phonon-assisted tunnelling (PhAT) in a double quantum dot (QD) molecule immersed in a cavity were studied under the quantum Markovian master equation formalism in order to account for dissipation phenomena. We explain how for higher PhAT rates, a stronger interaction between a QD and the cavity at off-resonance takes place through the resonant interaction of another QD and the cavity, where the QDs interact through tunnelling. A closer look at the system's allowed optical transitions as a function of PhAT rates showed coalescence of the transition energies, leading to a loss of spectroscopic resolution in the photoluminescence (PL) spectrum. This coalescence occurs at several exceptional points, suggesting a quantum dynamical phase transition.