Wide-band capacitance measurement on a semiconductor double quantum dot for studying tunneling dynamics

TL;DR

This paper introduces a wide-band capacitance measurement technique on a semiconductor double quantum dot to analyze tunneling dynamics and quantum capacitance across a broad frequency spectrum, enhancing understanding of quantum coupling.

Contribution

The study presents a novel on-chip lock-in detection method for wide-band capacitance measurement on a DQD, enabling detailed analysis of tunneling rates and quantum capacitance.

Findings

Capacitance can be measured from hertz to tens of gigahertz.

Phase and frequency dependence reveal tunneling rates.

Quantum capacitance reflects interdot quantum-mechanical coupling.

Abstract

We propose and demonstrate wide-band capacitance measurements on a semiconductor double-quantum dot (DQD) to study tunneling dynamics. By applying phase-tunable high-frequency signals independently to the DQD and a nearby quantum-point-contact charge detector, we perform on-chip lock-in detection of the capacitance associated with the single-electron motion over a wide frequency range from hertz to a few ten gigahertz. Analyzing the phase and the frequency dependence of the signal allows us to extract the characteristic tunneling rates. We show that, by applying this technique to the interdot tunnel coupling regime, quantum capacitance reflecting the strength of the quantum-mechanical coupling can be measured.