Beyond-adiabatic Quantum Admittance of a Semiconductor Quantum Dot at High Frequencies: Rethinking Reflectometry as Polaron Dynamics

TL;DR

This paper develops a quantum master equation approach to model the admittance of semiconductor quantum dots at microwave frequencies, revealing new photon-mediated regimes and enhancing understanding of their high-frequency electrical properties.

Contribution

It introduces a comprehensive formalism capturing various broadening regimes and proposes a new perspective on reflectometry as polaron dynamics in quantum dots.

Findings

Derived a general admittance expression including semiclassical, lifetime, and power broadening.

Identified two novel photon-mediated broadening regimes: Floquet broadening and photon loss broadening.

Provided a simulation framework for high-frequency quantum dot behavior and insights into experimental results.

Abstract

Semiconductor quantum dots operated dynamically are the basis of many quantum technologies such as quantum sensors and computers. Hence, modelling their electrical properties at microwave frequencies becomes essential to simulate their performance in larger electronic circuits. Here, we develop a self-consistent quantum master equation formalism to obtain the admittance of a quantum dot tunnel-coupled to a charge reservoir under the effect of a coherent photon bath. We find a general expression for the admittance that captures the well-known semiclassical (thermal) limit, along with the transition to lifetime and power broadening regimes due to the increased coupling to the reservoir and amplitude of the photonic drive, respectively. Furthermore, we describe two new photon-mediated regimes: Floquet broadening, determined by the dressing of the QD states, and broadening determined by photon loss in the system. Our results provide a method to simulate the high-frequency behaviour of QDs in a wide range of limits, describe past experiments, and propose novel explorations of QD-photon interactions.