Curator's Take
AI Commentary
This article demonstrates that Ga as quantum‑dot single‑photon emitters can retain near‑unity indistinguishability (I≈0.97) at temperatures far above the millikelvin regime, and shows a practical path to push that performance to I≈0.80 at 32 K using cavity‑enhanced Purcell acceleration. By quantifying how phonon coupling and nearby trion states degrade coherence and then experimentally mitigating those effects, the work bridges the gap between laboratory‑grade cryogenic sources and more deployable, Stirling‑cooled hardware—a long‑standing bottleneck for photonic quantum networks and sensing. The results complement recent advances in integrated silicon‑photonic platforms by offering a high‑quality, low‑noise source that could be packaged with on‑chip cavities without the need for dilution refrigerators.
— Mark Eatherly
Summary
For photonic quantum technology applications, sources capable of emitting photons with indistinguishability close to unity are essential. Ideally, these sources should not require demanding cooling systems. Here, we present temperature-dependent two-photon-interference measurements on photons produced by the radiative decay of the negative trion in a low-noise GaAs quantum dot, which are in quantitative agreement with theoretical calculations accounting for carrier-phonon interactions and coupling to excited states. While at at the lowest explored temperatures the emission linewidth reaches values only 6(2) % above the Fourier limit and the indistinguishability I between subsequently emitted photons reaches 0.966(6), the latter drops to 0.05(4) at 55 K. We show that this loss can be explained with the coupling with energetically close excited trion states and suggest that the photon indistinguishability at elevated temperatures can be increased by employing Purcell enhancement of the emission rate or by increasing the energy separation of the excited states. Using cavity-enhanced emission, we experimentally verify the first route and demonstrate an improvement in photon indistinguishability from 0.314(25) to 0.80(3) at 32 K, which - to our knowledge - is the highest reported value at such temperature.