Qubits with electrons on liquid helium

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 < ∼ 10 4 s −1 . We also calculate the dephasing rate, which is due primarily to ripplon scattering off an electron. This rate is < ∼ 10 2 s −1 for typical operation temperatures.

Chemistry in one dimension

“…44 Despite its simplicity, this model has been useful for studying the behavior of many physical systems, such as Rydberg atoms in external fields 45,46 or the dynamics of surface-state electrons in liquid helium 47,48 and its potential application to quantum computing. 49,50 Most work since Loudon has focused on one-electron ions 44,[51][52][53][54][55][56][57] and, to the best of our knowledge, no calculation has been reported for larger chemical systems. In part, this can be attributed to the ongoing controversy concerning the mathematical structure of the eigenfunctions.…”

Confinement effects on decay rate of surface electron states over liquid helium

“…The upper-bound limit lifetime of excited states of surface electrons in a quantum dot is found to be t < -10 6 -10 7 -s. Surface electrons (SEs) localized over the liquid helium surface have been an remarkable archetype for studying confined charged systems of low dimensionality [1,2]. In particular and more important, SE systems have been intensively investigated in the last years as potential candidate of qubit generators in quantum computation [3,4]. The main reasons for this are twofold.…”

“…In particular and more important, SE systems have been intensively investigated in the last years as potential candidate of qubit generators in quantum computation [3,4]. The main reasons for this are twofold.…”

“…The problem of the decay rate and the subband lifetime t, which is inversely proportional to decay rate, was first discussed in Ref. 4. The authors concluded that the contribution of the oneripplon scattering processes predominates.…”

“…On the contrary, for long wavelength ripplons N T q q ; / hw >>1. Therefore a linear T -dependence of the decay rate is obtained when only the one-ripplon process is considered [4].…”