Few-electron spin qubits in optically active GaAs quantum dots

[2504.19257] Few-electron spin qubits in optically active GaAs quantum dots Skip to main content Search Submit Donate Log in Search arXiv Press Enter to search · Advanced search Condensed Matter > Mesoscale and Nanoscale Physics arXiv:2504.19257 (cond-mat) [Submitted on 27 Apr 2025] Title: Few-electron spin qubits in optically active GaAs quantum dots Authors: Peter Millington-Hotze , Petr Klenovsky , Harry E. Dyte , George Gillard , Santanu Manna , Saimon F. Covre da Silva , Armando Rastelli , Evgeny A. Chekhovich View a PDF of the paper titled Few-electron spin qubits in optically active GaAs quantum dots, by Peter Millington-Hotze and 7 other authors View PDF HTML (experimental) Abstract: The knowledge of the energy spectrum completely defines the dynamics of a quantum system for a given initial state. This makes spectroscopy a key characterization technique when studying or designing qubits and complex quantum systems. In semiconductor quantum dots, the electronic quantum states can be probed through charge transport spectroscopy, but the electric current itself disrupts the fragile quantum system, and the technique is practically limited to gate-defined quantum dots. Epitaxial quantum dots benefit from excellent optical properties, but are usually incompatible with charge transport, while alternative spectroscopy techniques provide only limited information. Here we demonstrate a spectroscopy technique which utilizes nuclear spins as a non-invasive probe. By using spin currents instead of the charge currents we achieve near-equilibrium probing. Experiments are conducted on low-strain GaAs/AlGaAs epitaxial dots, revealing energy spectra for charge configurations with up to seven electrons and the subtle properties of the multi-electron states. The rich variety of observations includes long-lived spin-qubit states in s and p shells, ground-state phase transitions, strong spin-orbit coupling regimes, and anomalously fast nuclear spin diffusion. Experiments are backed up by good agreement with the first-principles configuration-interaction numerical modelling. Our work uncovers few-electron states as a new operating regime for optically active quantum dots. Accurate control and probing of many-body states offers a test-bed system for fundamental physics studies, while prospective technological applications include electron spin qubits with extended coherence and scalable electrical control. Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Cite as: arXiv:2504.19257 [cond-mat.mes-hall] (or arXiv:2504.19257v1 [cond-mat.mes-hall] for this version) https://doi.org/10.48550/arXiv.2504.19257 Focus to learn more arXiv-issued DOI via DataCite Related DOI : https://doi.org/10.1103/j8xw-w72c Focus to learn more DOI(s) linking to related resources Submission history From: Evgeny Chekhovich [ view email ] [v1] Sun, 27 Apr 2025 14:39:08 UTC (10,676 KB) Full-text links: Access Paper: View a PDF of the paper titled Few-electron spin qubits in optically active GaAs quantum dots, by Peter Millington-Hotze and 7 other authors View PDF HTML (experimental) TeX Source view license Current browse context: cond-mat.mes-hall < prev | next > new | recent | 2025-04 Change to browse by: cond-mat References & Citations NASA ADS Google Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... 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