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Quantum Dot
摘要： Valley splitting is a key feature of silicon-based spin qubits. Quantum dots in Si/SixGe1?x heterostructures reportedly suffer from a relatively low valley splitting, limiting the operation temperature and the scalability of such qubit devices. Here, we demonstrate a robust and large valley splitting exceeding 200 μeV in a gate-defined single quantum dot, hosted in molecular-beam-epitaxy-grown 28Si/SixGe1?x. The valley splitting is monotonically and reproducibly tunable up to 15% by gate voltages, originating from a 6-nm lateral displacement of the quantum dot. We observe static spin relaxation times T1 > 1 s at low magnetic fields in our device containing an integrated nanomagnet. At higher magnetic fields, T1 is limited by the valley hotspot and by phonon noise coupling to intrinsic and artificial spin-orbit coupling, including phonon bottlenecking.
关键词： valley splitting,spin relaxation,spin qubits,molecular-beam-epitaxy,silicon,quantum dot
更新于2025-09-19 17:13:59
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Electric field mediated large valley splitting in the van der Waals heterostructure WSe <sub/>2</sub> /CrI <sub/>3</sub>
摘要： In contrast to commonly used means such as the magnetic field, here an electric field is used to achieve a large valley splitting in the van der Waals (vdW) heterostructure WSe2/CrI3. CrI3 contributes to the spin moment. The electric field pushes the valence bands of Cr atoms close to those of the W atoms associated with pseudospin so that they can interact through the exchange interaction. The opposite helicities of pseudospin at the K and K′ points realize a valley splitting as large as 10.5 meV under an electric field of 0.1 V ??1. The underlying physics stems from the interlayer charge transfer, where the spin conservation plays a role.
关键词： van der Waals heterostructure,WSe2/CrI3,electric field,pseudospin,valley splitting
更新于2025-09-04 15:30:14