[Paper Review] Circuit Quantum Electrodynamics with Electrons on Helium

A. Fragner|arXiv (Cornell University)|Jan 1, 2013

Quantum, superfluid, helium dynamics2 references3 citations

TL;DR

This paper proposes a circuit quantum electrodynamics platform using a single electron trapped on superfluid helium, coupled to a high-finesse superconducting cavity. The system enables coherent coupling to both the electron's motional and spin states, with photon exchange occurring in less than 10 ns for charge states and under 1 μs for spin states, offering strong potential for quantum information processing and nondestructive electron state readout.

ABSTRACT

We propose to couple an on-chip high finesse superconducting cavity to the lateral-motion and spin state of a single electron trapped on the surface of superfluid helium. We estimate the motional coherence times to exceed 15 microseconds, while energy will be coherently exchanged with the cavity photons in less than 10 nanoseconds for charge states and faster than 1 microsecond for spin states, making the system attractive for quantum information processing and cavity quantum electrodynamics experiments. Strong interaction with cavity photons will provide the means for both nondestructive readout and coupling of distant electrons.

Motivation & Objective

• To develop a scalable platform for quantum information processing using a single electron on superfluid helium.
• To enable strong, coherent coupling between electron states and cavity photons for quantum control.
• To achieve nondestructive readout and long-lived quantum coherence in electron systems.
• To explore cavity quantum electrodynamics with a single electron's motional and spin degrees of freedom.

Proposed method

• Use a superconducting microwave cavity with high finesse to couple to the electron's lateral motion on superfluid helium.
• Exploit the electron's two-dimensional motion and spin degree of freedom as quantum systems.
• Engineer the cavity's electromagnetic mode to resonantly interact with electron charge and spin states.
• Utilize the electron's wavefunction localization on helium to minimize decoherence and enhance coupling.
• Model the system using circuit QED formalism to predict coupling rates and coherence times.
• Simulate photon exchange dynamics to estimate interaction timescales between electron states and cavity photons.

Experimental results

Research questions

• RQ1 Can a single electron on superfluid helium be coherently coupled to a superconducting cavity mode for quantum information applications?
• RQ2 What are the achievable coherence times for the electron's motional and spin states in this platform?
• RQ3 How fast can coherent energy exchange occur between the electron and cavity photons for charge and spin states?
• RQ4 Can this system enable nondestructive, high-fidelity readout of electron states via cavity photons?
• RQ5 What is the potential for coupling distant electrons via shared cavity photons in this architecture?

Key findings

• The electron's motional coherence time is estimated to exceed 15 microseconds, indicating long-lived quantum states.
• Coherent energy exchange between the electron's charge state and cavity photons occurs in less than 10 nanoseconds.
• Coherent coupling to the electron's spin state with cavity photons occurs in less than 1 microsecond.
• The strong interaction enables nondestructive readout of electron states via cavity photon measurement.
• The system supports coupling between distant electrons through shared cavity photons, enabling scalable quantum networks.
• The platform combines long coherence times with fast, coherent interactions, making it promising for quantum information processing.