Qubits with electrons on liquid helium

TL;DR

This paper investigates the dissipation mechanisms affecting electrons on liquid helium, assessing their suitability as qubits by estimating decay and dephasing rates due to ripplon and phonon scattering.

Contribution

It provides detailed estimates of decay and dephasing rates for electrons on helium, highlighting their potential for quantum computing applications and identifying dominant scattering mechanisms.

Findings

Decay rate estimated at less than 10^4 s^{-1} without magnetic field.

Dephasing rate primarily due to ripplon scattering, less than 10^2 s^{-1}.

Identifies key scattering mechanisms affecting qubit coherence.

Abstract

We study dissipation effects for electrons on the surface of liquid helium, which may serve as qubits of a quantum computer. Each electron is localized in a 3D potential well formed by the image potential in helium and the potential from a submicron electrode submerged into helium. We estimate parameters of the confining potential and characterize the electron energy spectrum. Decay of the excited electron state is due to two-ripplon scattering and to scattering by phonons in helium. We identify mechanisms of coupling to phonons and estimate contributions from different scattering mechanisms. Even in the absence of a magnetic field we expect the decay rate to be $\alt 10^4$ s$^{-1}$. We also calculate the dephasing rate, which is due primarily to ripplon scattering off an electron. This rate is $\alt 10^2$ s$^{-1}$ for typical operation temperatures.