Abstract
Photonic quantum technologies call for scalable quantum light sources that can be integrated, while providing the end user with single and entangled photons on demand. One promising candidate is strain free GaAs/AlGaAs quantum dots obtained by aluminum droplet etching. Such quantum dots exhibit ultra low multi-photon probability and an unprecedented degree of photon pair entanglement. However, different to commonly studied InGaAs/GaAs quantum dots obtained by the Stranski–Krastanow mode, photons with a near-unity indistinguishability from these quantum emitters have proven to be elusive so far. Here, we show on-demand generation of near-unity indistinguishable photons from these quantum emitters by exploring pulsed resonance fluorescence. Given the short intrinsic lifetime of excitons and trions confined in the GaAs quantum dots, we show single photon indistinguishability with a raw visibility of , without the need for Purcell enhancement. Our results represent a milestone in the advance of GaAs quantum dots by demonstrating the final missing property standing in the way of using these emitters as a key component in quantum communication applications, e.g., as quantum light sources for quantum repeater architectures.
Highlights
M ost applications in photonic quantum technologies rely on clean quantum interference of deterministically generated single and entangled photons
Quantum indistinguishability is a crucial ingredient for the creation of higher N00N states,[1,2] quantum teleportation[3] and swapping operations,[4] boson-sampling,[5,6] and photon-based quantum simulations.[7]
We apply cross-polarized pulsed resonance fluorescence to show that quantum dots derived from droplet etching do not suffer from additional dephasing mechanisms at short time scales and exhibit near-unity indistinguishability of on-demand generated single photons
Summary
The dephasing due to interactions with phonons and nearby trapped charge carriers is reduced.[34] To address the electric environment of the dot, we illuminate the sample with a low intensity white light source.[35,36] This results in a very clean spectrum with only one prominent line of the exciton transition and minor contribution of less than 2% from the trion transition as shown in a semi-logarithmic plot in Figure 2 a To show that this excitation scheme addresses the quantum dot coherently, we performed power-dependent pulsed resonance fluorescence measurements. Resonance fluorescence of GaAs quantum dots with near-unity photon indistinguishability; Rabi oscillation; time-correlated single-photon counting fit function including convolution with internal response function; polarization-resolved photoluminescence spectroscopy; and analysis of two-photon interference measurements (PDF).
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