Wigner time delay induced by a single quantum dot

TL;DR

This paper investigates Wigner time delays caused by a single quantum dot, revealing detuning-dependent delays up to 530 ps and deviations from traditional theory due to electron-phonon interactions.

Contribution

It provides the first experimental observation of Wigner time delays in a semiconductor quantum dot, including effects of electron-phonon interactions on scattering processes.

Findings

Detuning-dependent Wigner delays up to 530 ps observed.

Deviations from Wigner's theory due to incoherent scattering.

Microscopic theory supports delays up to 950 ps.

Abstract

Resonant scattering of weak coherent laser pulses on a single two-level system (TLS) realized in a semiconductor quantum dot is investigated with respect to a time delay between incoming and scattered light. This type of time delay was predicted by Wigner in 1955 for purely coherent scattering and was confirmed for an atomic system in 2013 [R. Bourgain et al., Opt. Lett. 38, 1963 (2013)]. In the presence of electron-phonon interaction we observe deviations from Wigner's theory related to incoherent and strongly non-Markovian scattering processes which are hard to quantify via a detuning-independent pure dephasing time. We observe detuning-dependent Wigner delays of up to 530\,ps in our experiments which are supported quantitatively by microscopic theory allowing for pure dephasing times of up to 950\,ps.