Coupling a single electron on superfluid helium to a superconducting resonator

Area of Science:

• Quantum physics
• Condensed matter physics
• Surface science

Background:

• Electrons on helium form a unique two-dimensional system at the liquid helium-vacuum interface.
• A small number of trapped electrons exhibit strong interactions, suitable for qubit applications.
• Trapped electrons' microwave frequencies allow integration with circuit quantum electrodynamics (cQED).

Purpose of the Study:

• To experimentally realize a cQED platform utilizing the orbitals of single electrons on helium.
• To investigate the interaction between single electrons on helium and microwave photons.
• To explore the potential for coherent control of electron states in this system.

Main Methods:

• Deterministic trapping of one to four electrons in a quantum dot.
• Integration of the electron trap with a microwave resonator.
• Measurement of electron response to microwave excitation.

Main Results:

• Successful realization of a cQED platform with single electrons on helium.
• Observation of strong single-electron-photon coupling (10 MHz), significantly exceeding the resonator linewidth (0.5 MHz).
• Demonstration of microwave interaction with trapped electrons.

Conclusions:

• The developed cQED platform enables microwave studies of electrons on helium.
• The strong coupling achieved is promising for quantum information processing.
• This work opens avenues for studying Wigner molecules and coherent control of electron spin and orbital states.