Condensed Matter Seminar Series

Seminar by Yann-Michel Niquet, CEA Grenoble, IRIG/MEM/L_Sim

Title :  Hole spin qubits in silicon and germanium: Lessons from modeling and simulation

Hole spin qubits in semiconductor quantum dots afford the unique advantage of an efficient electrical control.

This control is enabled by the strong spin-orbit interaction (SOI) in the valence band of semiconductors, which couples the spin to the real-space motion of the hole. The physics of hole spin qubits is particularly rich owing to the complex interplay between the SOI, the magnetic field, and the static and AC control electric fields. I will show how detailed microscopic modeling and simulation gives comprehensive insights into this physics, revealing general trends as well as subtle mechanisms at play.

I will focus, in particular, on the analysis of a recent experiment showing unprecedented hole spin lifetimes in a silicon nanowire device [Nature Nanotechnology 17, 1072 (2022)].

The simulations, in very good agreement with the experiments, highlight the competition between vertical and lateral confinement in the rectangular channel, leading to the existence of a “sweet spot” for dephasing, as well as the role of residual disorder. I will also discuss some unexpected spin driving mechanisms in Ge/SiGe heterostructures, unveiled by the microscopic simulations.