Dong-Rong Wu | Searcharxiv

arXiv2026

Individual Vanadium Dopants Form Deep In-Gap States in Monolayer WS2

Point defects in atomically thin materials have a strong impact on physical properties and those that induce in-gap states are advantageous for quantum information science and engineering (QISE). However, dopant engineering consisting of well-controlled synthesis and robust identification of in-gap states is challenging. In this work, we addressed this challenge by first using finely tuned chemical vapor deposition to incorporate vanadium dopants into a monolayer WS2 (V-WS2). Next, we utilized a suite of scanned probe microscopy techniques to identify and characterize individual dopants. The latter included conductive atomic force microscopy (cAFM), low temperature scanning tunneling microscopy and spectroscopy (STM/STS), and scanning transmission electron microscopy and unambiguously revealed that vanadium dopants form deep in-gap states 0.35 eV above the valence band maximum in V-WS2. Our experimental results are well supported by first principles calculations and taken together demonstrate that V-WS2 is a promising platform for QISE applications.

cond-mat.mtrl-sci↗

arXiv2026

Coherent Microwave Control of Optically Addressable Donor Qubits in ZnO

Optically addressable shallow donors in ZnO combine efficient spin-selective optical transitions with the potential for long spin coherence in an isotopically purifiable host lattice, making them an attractive platform for spin-photon quantum technologies. A key missing capability, however, has been coherent control beyond the small-angle rotations accessible with ultrafast optical pulses. Here we demonstrate coherent microwave control of implanted $^{115}\mathrm{In}$ donors in ZnO. Resonant optical pumping initializes and reads out the donor electron spin. Pulsed optically-detected magnetic resonance resolves the ten hyperfine transitions associated with the coupled $^{115}\mathrm{In}$ nuclear spin (I = 9/2) and reveals optical-pumping-induced nuclear spin polarization. We observe coherent Rabi oscillations with a maximum Rabi frequency of $\Omega/2\pi = 36.2 \pm 0.7$\;MHz, corresponding to a $\pi$-pulse time of 13.8$\pm$0.3\;ns, and characterize the spin coherence using Ramsey, Hahn echo and dynamical-decoupling measurements. Unexpectedly, the measured coherence is substantially shorter than reported in previous optical studies of donor spins in ZnO at high magnetic field. Control experiments rule out several simple explanations including microwave heating and instantaneous diffusion from the driven donor ensemble, leaving an open question regarding the origin of decoherence at low magnetic field in microwave-controlled ZnO donors. These results establish microwave control of ZnO donor qubits with resonant optical access to specific donor species. More broadly, they demonstrate that coherent microwave control can be achieved in optically addressable spin systems with nanosecond-scale inhomogeneous dephasing, enabling field-, temperature-, and materials-dependent studies of coherence-limiting mechanisms and the development of optically interfaced electron-nuclear spin registers.

quant-ph↗