Mainz 2026 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 11: QuanTour I – Single Photons & Foundations

Q 11.7: Vortrag

Montag, 2. März 2026, 18:45–19:00, P 7

Pulsed to continuous wave microcavity-quantum dot (in)coherent dynamics — •Mio Poortvliet and Wolfgang Löffler — Leiden Institute of Physics, Leiden University, Leiden, The Netherlands

Semiconductor quantum dots are a promising single photon source, when excited correctly. We focus on resonant excitation, this allows coherent control and is flexible to implement. The response from the quantum dot is well understood for continuous wave excitation, where a stream of single photons is produced without well-defined time-bins. Using pulsed excitation light with a pulse length shorter than relevant QD decoherence times is also well understood, population inversion above 50% can produce one photon per time bin deterministically.

In this experiment, we study a charged InGaAs quantum dot in a polarization-split monolithic micro-cavity and excite it using a custom pulse generator enabling pulse lengths from 20 ps to many times the QD lifetime. With this, we investigate how the cavity-quantum dot system behaves under various excitation conditions, from pulsed to continuous-wave, and for different quantum dot and laser detunings. We measure the characteristic chevron pattern of Rabi oscillations, modified by cavity field enhancement and cavity-QD hybridization. We are able to reproduce this data accurately by careful simulation. By simultaneously measuring the second order correlation function we observe how the photon statistics oscillate between anti-bunched and bunched, and by chaning the detuning we measure significant bunching likely from a single photon subtracted coherent state.

Keywords: single photon source; epitaxial quantum dots; Jaynes Cummings; picosecond optical pulses; micro cavity