# Valley dependent anisotropic spin splitting in silicon quantum dots

## TL;DR

This paper reports the experimental observation of valley-dependent anisotropic spin splitting in silicon quantum dots, highlighting the roles of spin-orbit interaction and interface inhomogeneities in spin control for quantum computing.

## Contribution

It provides the first experimental evidence and atomistic analysis of valley-dependent spin anisotropy in silicon quantum dots, emphasizing the impact of atomic-scale interface details.

## Key findings

- Valley-dependent anisotropic spin splitting observed experimentally.
- Spin-orbit interaction significantly influences spin anisotropy.
- Interface inhomogeneities affect spin splittings and valley dependence.

## Abstract

Spin qubits hosted in silicon (Si) quantum dots (QD) are attractive due to their exceptionally long coherence times and compatibility with the silicon transistor platform. To achieve electrical control of spins for qubit scalability, recent experiments have utilized gradient magnetic fields from integrated micro-magnets to produce an extrinsic coupling between spin and charge, thereby electrically driving electron spin resonance (ESR). However, spins in silicon QDs experience a complex interplay between spin, charge, and valley degrees of freedom, influenced by the atomic scale details of the confining interface. Here, we report experimental observation of a valley dependent anisotropic spin splitting in a Si QD with an integrated micro-magnet and an external magnetic field. We show by atomistic calculations that the spin-orbit interaction (SOI), which is often ignored in bulk silicon, plays a major role in the measured anisotropy. Moreover, inhomogeneities such as interface steps strongly affect the spin splittings and their valley dependence. This atomic-scale understanding of the intrinsic and extrinsic factors controlling the valley dependent spin properties is a key requirement for successful manipulation of quantum information in Si QDs.