# High Resolution Valley Spectroscopy of Si Quantum Dots

## TL;DR

This paper investigates the valley states in silicon quantum dots using microwave cavity spectroscopy, revealing how temperature and bias influence valley occupation and enabling extraction of key quantum parameters.

## Contribution

It introduces a method combining cavity input-output theory and a four-level model to accurately measure valley splittings and tunnel couplings in Si quantum dots.

## Key findings

- Valley states influence cavity transmission signals.
- Temperature and bias increase valley occupation.
- Valley splittings and tunnel couplings are quantitatively extracted.

## Abstract

We study an accumulation mode Si/SiGe double quantum dot (DQD) containing a single electron that is dipole coupled to microwave photons in a superconducting cavity. Measurements of the cavity transmission reveal dispersive features due to the DQD valley states in Si. The occupation of the valley states can be increased by raising temperature or applying a finite source-drain bias across the DQD, resulting in an increased signal. Using cavity input-output theory and a four-level model of the DQD, it is possible to efficiently extract valley splittings and the inter- and intra-valley tunnel couplings.