Global modeling of the asymmetric hotspot-enhanced Rabi frequency

Determine a consistent magnetic-field-independent dependence of the intervalley dipole matrix element on quantum-dot position, or otherwise establish the mechanism responsible for the asymmetric Rabi-frequency enhancement about the spin-valley hotspot, within a theory that quantitatively describes the measurements.

Background

The measured Rabi frequency increases near the spin-valley hotspot, as predicted for intrinsic spin-orbit coupling, but its enhancement is strongly asymmetric with respect to the detuning between valley splitting and Zeeman splitting. The four-state spin-valley model discussed in the paper captures the enhancement only qualitatively and fails increasingly far from the hotspot, particularly on the high-valley-splitting side.

The paper considers whether the intervalley dipole matrix element varies with dot position because changing the virtual gate also changes the electron wave function and sampled alloy disorder. Although a linearized position dependence improves individual fits, the authors cannot obtain parameters that are consistent across magnetic fields, leaving the origin and proper theoretical description of the asymmetry unresolved.