Electrically Protected Valley-Orbit Qubits in Silicon

TL;DR

This paper demonstrates that valley-orbit hybridization in silicon quantum dots can protect qubits from charge noise, using LZSM interferometry to probe and analyze the valley degrees of freedom.

Contribution

It introduces a method to use LZSM interferometry on silicon double quantum dots to explore valley hybridization and its potential for noise-resistant qubits.

Findings

LZSM interference pattern is asymmetric and persists beyond typical decoherence times.

Valley-orbit hybridization offers protection against charge noise.

Potential for engineering charge-noise-insensitive silicon qubits.

Abstract

Electrons confined in Si quantum dots possess orbital, spin, and valley degrees of freedom (d.o.f.). We perform Landau-Zener-Stuckelberg-Majorana (LZSM) interferometry on a Si double quantum dot that is strongly coupled to a microwave cavity to probe the valley d.o.f. The resulting LZSM interference pattern is asymmetric as a function of level detuning and persists for drive periods that are much longer than typical charge decoherence times. By correlating the LZSM interference pattern with charge noise measurements, we show that valley-orbit hybridization provides some protection from the deleterious effects of charge noise. Our work opens the possibility of harnessing the valley d.o.f. to engineer charge-noise-insensitive qubits in Si.