A Unipolar Quantum Dot Diode Structure for Advanced Quantum Light Sources

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. Blinkingfree 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.

Machine learning enhanced evaluation of semiconductor quantum dots

“…The QDs are located in the vertical antinode of a planar cavity formed by a bottom distributed Bragg reflector (DBR) and a lower reflectivity top DBR. More information on the samples can be found in 22 , alongside comprehensive optical and quantum optical characterisations. Using an above-band excitation laser close to saturation, a dataset of emission spectra is recorded in a spectral range of in , thus giving an input dimension of .…”

“…While there are several fabrication techniques and material compositions for the realisation of QDs, for this work, we consider self-assembled QD samples grown in the Stranski–Krastanow mode on a platform using molecular beam epitaxy 22 . A schematic cross-section of such an QD wafer is given in Fig.…”

Highly Indistinguishable Single Photons from Droplet-Etched GaAs Quantum Dots Integrated in Single-Mode Waveguides and Beamsplitters

“…Several quantum technologies such as optical quantum computing, quantum communication, quantum sensing and quantum simulation will strongly benefit from small-footprint photonic integrated circuits (PICs) due to the high scalability of the approach. , A central part of these technologies is efficient on-demand sources of single and indistinguishable photons. In this regard, semiconductor quantum dots (QDs) are very promising candidates, showing very pure single-photon emission, high count rates, − and emission linewidths close to the Fourier limit. − The compatibility of QDs with PICs has been demonstrated in various experiments, ranging from direct integration in fully monolithically grown samples − to different hybrid integration techniques − and fiber-to-chip or chip-to-chip coupling. − In order to increase the chip efficiency, different cavities compatible with waveguides (WGs) were introduced, which on the one hand increase the coupling efficiency into the WG and on the other hand shorten the decay time via the Purcell effect, thus allowing higher repetition rates. − Another important point with respect to the upscaling of quantum PICs is a tuning method to compensate for the spectral mismatch between individual emitters and enable two-photon interference. Several tuning mechanisms have already been demonstrated for QDs in PICs, including local temperature tuning via laser heating, , local and global strain, − and electrical fields. − Nevertheless, interference between two WG-integrated remote QDs has been shown recently without an additional energy-tuning knob …”

Unveiling the 3D Morphology of Epitaxial GaAs/AlGaAs Quantum Dots

“…Semiconductor quantum dots (QDs) embedded within a single-crystalline host matrix represent exceptional sources of nonclassical photons, playing a pivotal role in quantum technologies. − The GaAs/AlGaAs QDs produced through droplet etching and nanohole infilling (DENI) are highly attractive due to their anticipated minimal crystal defects and outstanding optical properties, excelling in key aspects such as pure, bright, , and indistinguishable , single-photon emission with line widths close to Fourier limit, − as well as strong multiphoton entanglement. , After enhancing their optical properties through postgrowth techniques, such as electrical fields, , strain fields, ,, and optical cavities, they can be utilized in a variety of quantum photonic systems, including entanglement swapping , or quantum key distribution . It is important to note that understanding and controlling the morphology of DENI QDs, in particular, their symmetry and material composition, is essential to achieve the desired optical properties.…”