Resonant and Anti-resonant Exciton-Phonon Coupling in Quantum Dot Molecules
Abstract
Optically active quantum dot molecules (QDMs) can host multi-spin quantum states with the potential for the deterministic generation of photonic graph states with tailored entanglement structures. Their usefulness for the generation of such non-classical states of light is determined by orbital and spin decoherence mechanisms, particularly phonon-mediated processes dominant at energy scales up to a few millielectronvolts. Here, we directly measure the spectral function of orbital phonon relaxation in a QDM and benchmark our findings against microscopic kp theory. Our results reveal phonon-mediated relaxation rates exhibiting pronounced resonances and anti-resonances, with rates ranging from several ten ns to tens of s. Comparison with a kinetic model reveals the voltage (energy) dependent phonon coupling strength and fully explains the interplay between phonon-assisted relaxation and radiative recombination. These anti-resonances can be leveraged to increase the lifetime of energetically unfavorable charge configurations needed for realizing efficient spin-photon interfaces and multi-dimensional cluster states.
Keywords
Cite
@article{arxiv.2505.09906,
title = {Resonant and Anti-resonant Exciton-Phonon Coupling in Quantum Dot Molecules},
author = {Michelle Lienhart and Krzysztof Gawarecki and Markus Stöcker and Frederik Bopp and Charlotte Cullip and Nadeem Akhlaq and Christopher Thalacker and Johannes Schall and Sven Rodt and Arne Ludwig and Dirk Reuter and Stephan Reitzenstein and Kai Müller and Paweł Machnikowski and Jonathan J. Finley},
journal= {arXiv preprint arXiv:2505.09906},
year = {2025}
}