Observation of resonance fluorescence and the Mollow triplet from a coherently driven site-controlled quantum dot

This work was funded by project SIQUTE (contract EXL02) of the European Metrology Research Programme (EMRP). The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. Support was provided from the Villum Foundation via the VKR Centre of Excellence NATEC.Resonant excitation of solid state quantum emitters has the potential to deterministically excite a localized exciton while ensuring maximally coherent emission. In this work, we demonstrate the coherent coupling of an exciton localized in a lithographically positioned, site-controlled semiconductor quantum dot to an external resonant laser field. For strong continuous-wave driving we observe the characteristic Mollow triplet and analyze the Rabi splitting and sideband widths as a function of driving strength and temperature. The sideband widths increase linearly with temperature and the square of the driving strength, which we explain via coupling of the exciton to longitudinal acoustic phonons. We also find an increase of the Rabi splitting with temperature, which indicates a temperature-induced delocalization of the excitonic wave function resulting in an increase of the oscillator strength. Finally, we demonstrate coherent control of the exciton excited state population via pulsed resonant excitation and observe a damping of the Rabi oscillations with increasing pulse area, which is consistent with our excitonx2013;photon coupling model. We believe that our work outlines the possibility to implement fully scalable platforms of solid state quantum emitters. Such scalability is one of the key prerequisites for more advanced, integrated nanophotonic quantum circuits.PostprintPeer reviewe

Intrinsic and environmental effects on the interference properties of a high-performance quantum dot single-photon source

We acknowledge support by the State of Bavaria and the German Ministry of Education and Research (BMBF) within the project Q.com. J.I.-S. and J.M. acknowledge support from the Danish Research Council (DFF-4181-00416) and Villum Fonden (NATEC Centre). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 703193.We report a joint experimental and theoretical study of the interference properties of a single-photon source based on a In(Ga)As quantum dot embedded in a quasiplanar GaAs microcavity. Using resonant laser excitation with a pulse separation of 2 ns, we find near-perfect interference of the emitted photons, and a corresponding indistinguishability of I=(99.6^+0.4_−1.4)%. For larger pulse separations, quasiresonant excitation conditions, increasing pump power, or with increasing temperature, the interference contrast is progressively and notably reduced. We present a systematic study of the relevant dephasing mechanisms and explain our results in the framework of a microscopic model of our system. For strictly resonant excitation, we show that photon indistinguishability is independent of pump power, but strongly influenced by virtual phonon-assisted processes which are not evident in excitonic Rabi oscillations.Publisher PDFPeer reviewe

Time-bin-encoded boson sampling with a single-photon device

This work was supported by the National Natural Science Foundation of China, the Chinese Academy of Sciences, the National Fundamental Research Program, and the State of Bavaria.Boson sampling is a problem strongly believed to be intractable for classical computers, but can be naturally solved on a specialized photonic quantum simulator. Here, we implement the first time-bin-encoded boson sampling using a highly indistinguishable (∼94%) single-photon source based on a single quantum-dot-micropillar device. The protocol requires only one single-photon source, two detectors, and a loop-based interferometer for an arbitrary number of photons. The single-photon pulse train is time-bin encoded and deterministically injected into an electrically programmable multimode network. The observed three- and four-photon boson sampling rates are 18.8 and 0.2 Hz, respectively, which are more than 100 times faster than previous experiments based on parametric down-conversion.PostprintPeer reviewe

Two-photon interference from a quantum dot microcavity : persistent pure dephasing and suppression of time jitter

We demonstrate the emission of highly indistinguishable photons from a quasi-resonantly pumped coupled quantum dot-microcavity system operating in the regime of cavity quantum electrodynamics. Changing the sample temperature allows us to vary the quantum dot-cavity detuning and, on spectral resonance, we observe a threefold improvement in the Hong-Ou-Mandel interference visibility, reaching values in excess of 80%. Our measurements off-resonance allow us to investigate varying Purcell enhancements, and to probe the dephasing environment at different temperatures and energy scales. By comparison with our microscopic model, we are able to identify pure dephasing and not time jitter as the dominating source of imperfections in our system.Publisher PDFPeer reviewe

Impact of nanomechanical resonances on lasing from electrically pumped quantum dot micropillars

The work was sponsored by the German Ministry of Education and Research (BMBF) within the RELQUSA project (FKZ: 13N12462) and the Deutsche Forschungsgemeinschaft (Ba1549/14-1 and Collaborative Research Centre TRR 142). The work was also supported by the state of Bavaria. A.V.A. acknowledges the Alexander-von-Humboldt Foundation. S.H. acknowledges support by the Royal Society and the Wolfson Foundation. Date of Acceptance: 06/01/2015We use a picosecond acoustics technique to modulate the laser output of electrically pumped GaAs/AlAs micropillar lasers with InGaAs quantum dots. The modulation of the emission wavelength takes place on the frequencies of the nanomechanical extensional and breathing (radial) modes of the micropillars. The amplitude of the modulation for various nanomechanical modes is different for every micropillar which is explained by a various elastic contact between the micropillar walls and polymer environment.Publisher PDFPeer reviewe