Observation of Mollow Triplets with Tunable Interactions in Double Lambda Systems of Individual Hole Spins

TL;DR

This study demonstrates the observation and control of Mollow triplets in individual hole spins within double-lambda quantum dot systems, revealing tunable interactions and anticrossings under strong resonant driving.

Contribution

It presents the first experimental observation of Mollow triplets with tunable interactions in double-lambda systems of individual hole spins in quantum dots, supported by quantum-optical modeling.

Findings

Observation of Mollow triplets in quantum dot systems.

Tunable anticrossings controlled by laser polarization.

Quantum-optical model accurately describes the spectra.

Abstract

Although individual spins in quantum dots have been studied extensively as qubits, their investigation under strong resonant driving in the scope of accessing Mollow physics is still an open question. Here, we have grown high quality positively charged quantum dots embedded in a planar microcavity that enable enhanced light-matter interactions. Under a strong magnetic field in the Voigt configuration, individual positively charged quantum dots provide a double-lambda level structure. Using a combination of above-band and resonant excitation, we observe the formation of Mollow triplets on all optical transitions. We find that when the strong resonant drive power is used to tune the Mollow triplet lines through each other, we observe anticrossings. We also demonstrate that the interaction that gives rise to the anticrossings can be controlled in strength by tuning the polarization of the resonant laser drive. Quantum-optical modeling of our system fully captures the experimentally observed spectra and provides insight on the complicated level structure that results from the strong driving of the double-lambda system.