Microwave quantum optics as a direct probe of the Overhauser field in a quantum-dot CQED device

TL;DR

This paper proposes a theoretical method using microwave quantum optics in a quantum-dot CQED device to directly measure the Overhauser field, leveraging EIT and Fano interference to achieve high-resolution detection despite spin bath fluctuations.

Contribution

It introduces a novel approach to probe the Overhauser field in quantum dots via microwave spectroscopy in a CQED setup, highlighting the use of EIT and Autler-Townes splitting for precise measurement.

Findings

EIT scheme enables high-resolution Overhauser field detection.

Reflection spectrum shows Fano interference effects.

Autler-Townes splitting indicates strong nuclear spin fields.

Abstract

We show theoretically that a quantum-dot circuit quantum electrodynamics (CQED) device can be used as a probe of the Overhauser field in quantum dots. By coupling a transmission line to the interdot tunneling gate, an electromagnetically-induced-transparency (EIT) scheme can be established, whose Fano-type interference leads to a sharp curvature in the reflection spectrum around resonance. This sharp feature persists even in the presence of the fluctuating spin bath, rendering a high-resolution method to extract the bath's statistical information. For strong nuclear spin fields, the reflection spectrum exhibits an Autler-Townes splitting, where the peak locations indicate the strengths of the Overhauser field gradient (OFG).