Electrical control of optically active single spin qubits in ZnSe

Electrons bound to shallow donors in ZnSe quantum wells are promising candidates for optically addressable spin qubits and single-photon sources. However, their optical coherence is often limited by spectral broadening caused by charge fluctuations in the local environment. We report the first electrical control of single donors in ZnSe quantum wells using an in-plane electric field. The field induces a Stark shift, tuning the emission energy over 30 times the inhomogeneous linewidth, sufficient to overcome emitter-to-emitter spectral inhomogeneity. Concurrently, the field stabilizes trap occupancy, leading to a twofold narrowing of the optical linewidth and the suppression of spectral wandering. A trap-dynamics statistical model qualitatively reproduces these observations and elucidates the mechanism of field-assisted and optical charge noise suppression. Our results identify electrical control as a versatile pathway to strongly improved optical and spin addressability.