A Unipolar Quantum Dot Diode Structure for Advanced Quantum Light Sources
Tim Strobel, Jonas H. Weber, Marcel Schmidt, Lukas Wagner, Lena Engel, Michael Jetter, Andreas D. Wieck, Simone Luca Portalupi, Arne Ludwig, Peter Michler
Abstract
Triggered, indistinguishable single photons are crucial in various quantum photonic implementations. Here, we realize a novel n + –i–n ++ diode structure embedding semiconductor quantum dots: the gated device enables spectral tuning of the transitions and deterministic control of the charged states. Blinking-free single-photon emission and high two-photon indistinguishability are observed. The line width’s temporal evolution is investigated across over 6 orders of magnitude time scales, combining photon-correlation Fourier spectroscopy, high-resolution photoluminescence spectroscopy, and two-photon interference (visibility of V TPI,2ns = (85.8 ± 2.2)% and V TPI,9ns = (78.3 ± 3.0)%). Most of the dots show no spectral broadening beyond ∼9 ns time scales, and the photons’ line width ((420 ± 30) MHz) deviates from the Fourier-transform limit by a factor of 1.68. The combined techniques verify that most dephasing mechanisms occur at time scales ≤2 ns, despite their modest impact. The presence of n-doping implies higher carrier mobility, enhancing the device’s appeal for high-speed tunable, high-performance quantum light sources.