Strong intervalley mixing between copropagating quantum Hall edge channels in a silicon MOSFET

Abstract:Copropagating quantum Hall edge channels provide a promising platform for compact electron interferometry and flying quantum states. In silicon, the valley degree of freedom offers a natural alternative to spin-resolved edge channels because spin-flip scattering is strongly suppressed by the weak spin-orbit interaction. Here, we investigate interchannel transitions between copropagating valley edge channels in a double-layer-gated silicon metal-oxide-semiconductor field-effect transistor. With the bulk filling factor set to $\nu=2$, two spin-polarized valley edge channels are brought into close proximity near a depleted side gate. We observe strong intervalley mixing, with a transition probability close to 1/2, indicating nearly complete equilibration between the two valley edge channels. In contrast, interchannel transport between edge channels with different spin orientations shows negligible transition probability, consistent with suppressed spin-flip scattering in silicon. These results demonstrate that intervalley coupling at a Si/SiO$_2$ interface can provide a beam-splitter-like operation for copropagating valley edge channels, establishing a key building block toward compact silicon quantum Hall interferometers.

Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Quantum Physics (quant-ph)

arXiv:2607.15675 [cond-mat.mes-hall]

(or arXiv:2607.15675v1 [cond-mat.mes-hall] for this version)

https://doi.org/10.48550/arXiv.2607.15675 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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