%AHanschke, Lukas%AFischer, Kevin%AAppel, Stefan%ALukin, Daniil%AWierzbowski, Jakob%ASun, Shuo%ATrivedi, Rahul%AVučković, Jelena%AFinley, Jonathan%AMüller, Kai%BJournal Name: npj Quantum Information; Journal Volume: 4; Journal Issue: 1; Related Information: CHORUS Timestamp: 2022-12-20 18:02:16 %D2018%INature Publishing Group %JJournal Name: npj Quantum Information; Journal Volume: 4; Journal Issue: 1; Related Information: CHORUS Timestamp: 2022-12-20 18:02:16 %K %MOSTI ID: 10154110 %PMedium: X %TQuantum dot single-photon sources with ultra-low multi-photon probability %XAbstract

High-quality sources of single photons are of paramount importance for quantum communication, sensing, and metrology. To these ends, resonantly excited two-level systems based on self-assembled quantum dots have recently generated widespread interest. Nevertheless, we have recently shown that for resonantly excited two-level systems, emission of a photon during the presence of the excitation laser pulse and subsequent re-excitation results in a degradation of the obtainable single-photon purity. Here, we demonstrate that generating single photons from self-assembled quantum dots with a scheme based on two-photon excitation of the biexciton strongly suppresses the re-excitation. Specifically, the pulse-length dependence of the multi-photon error rate reveals a quadratic dependence in contrast to the linear dependence of resonantly excited two-level systems, improving the obtainable multi-photon error rate by several orders of magnitude for short pulses. We support our experiments with a new theoretical framework and simulation methodology to understand few-photon sources.

%0Journal Article