Probing the Quantum Capacitance of Rydberg Transitions of Surface Electrons on Liquid Helium via Microwave Frequency Modulation
Abstract
We present a method for probing the quantum capacitance associated with the Rydberg transition of surface electrons on liquid helium using radio-frequency (RF) reflectometry. Resonant microwave excitation of the Rydberg transition induces a redistribution of image charges on capacitively coupled electrodes, giving rise to a quantum capacitance originating from adiabatic state transitions and the finite curvature of the energy bands. By applying frequency-modulated resonant microwaves to drive the Rydberg transition, we systematically measured a capacitance sensitivity of 0.34~aF/ for our RF reflectometry scheme. This sensitivity is sufficient to detect the Rydberg transition of a single electron, offering a scalable pathway toward qubit readout schemes based on surface electrons on helium.
Keywords
Cite
@article{arxiv.2504.09890,
title = {Probing the Quantum Capacitance of Rydberg Transitions of Surface Electrons on Liquid Helium via Microwave Frequency Modulation},
author = {Asher Jennings and Ivan Grytsenko and Yiran Tian and Oleksiy Rybalko and Jun Wang and Itay Josef Barabash and Erika Kawakami},
journal= {arXiv preprint arXiv:2504.09890},
year = {2026}
}