Appl. Phys. Lett. 108, 021104 (2016)

Single-photon sources based on semiconductor quantum dots (QDs) are promising platforms for future quantum hardware. However, the achievement of modulation speeds exceeding the GHz range is limited by the intrinsic radiative lifetime of the QD optical transition. Now, Alexander Schlehahn and co-workers from Technische Universität Berlin in Germany and Technion-Israel Institute of Technology have demonstrated the generation of a single-photon pulse train at a 1 GHz repetition rate by electro-optically exciting InGaAs QD microlenses embedded in a GaAs layer. The QD microlenses were electrically addressed by an integrated microprobe needle and excited by a continuous-wave diode laser emitting at 651 nm. When electrical pulses with a width of 8.2 ns and amplitude of 3 V were applied to the QD microlenses, a pronounced pulsed emission triggered by the rising edge of the electrical pulse was observed. The non-classical nature of the photon pulse train was proved by intensity autocorrelation measurements. In combination with resonant excitation schemes, this holds promise for the realization of efficient, ultrafast sources of indistinguishable photons.