Phonon-assisted population inversion of a single quantum dot

TL;DR

This paper demonstrates a method to achieve population inversion in a single quantum dot using phonon-assisted relaxation, enabling improved control of quantum dot qubits with a maximum exciton population of 0.67.

Contribution

It introduces a phonon-assisted approach to invert population in a quantum dot, expanding the control techniques for quantum dot qubits.

Findings

Maximum exciton population of 0.67 achieved.

Phonon sideband mapped using two-color pump-probe.

Phonon bath enhances optically driven quantum dot control.

Abstract

We demonstrate an approach to realize the population inversion of a single InGaAs/GaAs quantum dot, which is driven by a laser pulse tuned within the neutral exciton phonon sideband. The inversion is achieved by rapid thermalization of the optically dressed states via phonon-assisted relaxation. A maximum exciton population of 0.67 $\pm$ 0.06 is measured for a laser tuned 0.83 meV to higher energy and the phonon sideband is mapped using a two-color pump-probe technique. Our experiments reveal that, in accordance with theory, the phonon-bath provides additional functionality for an optically driven quantum dot qubit.