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

Understand

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.