Optical and magnetic response by design in GaAs quantum dots
quant-ph
/ Authors
Christian Schimpf, Ailton J. Garcia, Zhe X. Koong, Giang N. Nguyen, Lukas L. Niekamp, Martin Hayhurst Appel, Ahmed Hassanen, James Waller, Yusuf Karli, Saimon Philipe Covre da Silva
and 17 more authors
Julian Ritzmann, Hans-Georg Babin, Andreas D. Wieck, Anton Pishchagin, Nico Margaria, Ti-Huong Au, Sebastien Bossier, Martina Morassi, Aristide Lemaitre, Pascale Senellart, Niccolo Somaschi, Arne Ludwig, Richard Warburton, Mete Atatüre, Armando Rastelli, Michał Gawełczyk, Dorian Gangloff
/ Abstract
Quantum networking technologies use spin qubits and their interface to single photons as core components of a network node. This necessitates the ability to co-design the magnetic- and optical-dipole response of a quantum system. These properties are notoriously difficult to design in many solid-state systems, where spin-orbit coupling and the crystalline environment for each qubit create inhomogeneity of electronic g-factors and optically active states. Here, we show that GaAs quantum dots (QDs) obtained via the quasi-strain-free local droplet etching epitaxy growth method provide spin and optical properties predictable from assuming the highest possible QD symmetry. Our measurements of electron and hole g-tensors and of transition dipole moment orientations for charged excitons agree with our predictions from a multiband k.p simulation constrained only by a single atomic-force-microscopy reconstruction of QD morphology. This agreement is verified across multiple wavelength-specific growth runs at different facilities within the range of 730 nm to 790 nm for the exciton emission. Remarkably, our measurements and simulations track the in-plane electron g-factors through a zero-crossing from -0.1 to 0.3 and linear optical dipole moment orientations fully determined by an external magnetic field. The robustness of our results demonstrates the capability to design - prior to growth - the properties of a spin qubit and its tunable optical interface best adapted to a target magnetic and photonic environment with direct application for high-quality spin-photon entanglement.