Highly coherent single photon emission from charge tunable GaAs quantum dots*

Efficient generation and detection of coherent single photons are key to advances in photonic quantum technologies. Among many quantum emitters, GaAs quantum dots are promising as they emit close to the red part of the spectrum. This wavelength range is important as it contains the peak sensitivity of silicon detectors and operating wavelengths of a rubidium memory. However, GaAs QDs usually suffer from random telegraph noise (blinking) due to an unstable charge environment. This charge noise also leads to broadened optical linewidths and photon-bunching (J.-P. Jahn, et al., Phys. Rev. B 92, 245439 (2015)).
We present a low-noise n-i-p diode with GaAs quantum dots embedded in the intrinsic layer (L. Zhai, et al. Nat. Commun. 11, 4745 (2020)). The diode stabilizes the charge environment resulting in QD linewidths just marginally above the lifetime limit and elimination of blinking even on a millisecond timescale. Moreover, the QD emission exhibits highly pure and coherent single photons which can be frequency-tuned via the quantum-confined Stark effect.