Quantum computing using floating electrons on cryogenic substrates: Potential And Challenges

TL;DR

This review explores floating-electron-based qubits on cryogenic substrates, highlighting their potential for long coherence times and discussing recent experimental and theoretical advances in their development.

Contribution

It provides a comprehensive survey of recent experiments and theoretical proposals for floating-electron qubits, emphasizing spin-charge hybridization and control mechanisms.

Findings

Electrons on liquid helium or neon surfaces show promise as qubits.

Recent experiments demonstrate potential for long coherence times.

Charge-spin coupling enables control and readout of qubits.

Abstract

In this review, we introduce a developing qubit platform: floating-electron-based qubits. Electrons floating in a vacuum above the surface of liquid helium or solid neon emerge as promising candidates for qubits, especially due to their expected long coherence times. Despite being in the early stages, a variety of recent experiments from different groups have shown substantial potential in this role. We survey a range of theoretical proposals and recent experiments, primarily focusing on the use of the spin state as the qubit state, wherein the spin and charge states are hybridized. Throughout these proposals and experiments, the charge state is coupled to an LC resonator, which facilitates both the control and readout mechanisms for the spin state via an artificially introduced spin-charge coupling.