Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Vacuum and Surface Science

Electrons Floating on Liquid Helium and Solid Neon Surfaces

Ivan Grytsenko, Xianjing Zhou, Erika Kawakami

Published Feb 9, 2026• 0 citations
Publisher

Abstract

Electrons trapped above cryogenic substrates such as liquid helium and solid neon form exceptionally clean physical systems, since they reside in vacuum and are largely isolated from environmental noise. A recent breakthrough has been the realization of charge qubits using electrons on solid neon surfaces, with coherence times reaching T2 = 2T1 ≈ 100 µs. In this article, we describe in detail the preparation of cryogenic substrates, electron deposition and the measurement of electron mobility. We further discuss the differences in surface morphology between helium and neon, their impact on mobility and qubit performance, and emphasize the necessity of systematic surface characterization as a means to optimize cryogenic substrate preparation and electron deposition.

DOI
10.1380/vss.69.68

Related papers

Quantum computing using floating electrons on cryogenic substrates: Potential and challenges

A. Jennings, Xianjing Zhou, Ivan Grytsenko +1 more

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.

arXiv:2310.04119•Applied Physics Letters•Mar 18, 2024•18 citations

On the Origin of Coherent Gigahertz Two-Level States in Electron-on-Neon Systems

Kaiwen Zheng

Electrons floating on condensed noble-gas substrates form a remarkably clean material system that is minimally influenced by the underlying host material, and recent experiments have explored their potential as a qubit platform. In particular, single electrons floating on solid neon thin films have attracted significant interest because they exhibit long coherence times when probed with superconducting circuits at frequencies around 6 GHz. Surprisingly, however, the energy spectrum of these qubits resembles that of a two-level-system defect more than the spectrum expected from the Coulomb potential defined by the bias electrodes. In this thesis, I first review floating-electron systems and the experimental methods used to probe their quantum states. I then show that electron-on-neon qubits with transition frequencies of a few GHz are observed only on neon films deposited on silicon surfaces, and not on neon films deposited on sapphire. Motivated by this observation, I propose a model in which a floating electron on the neon surface interacts with fixed positive charge defects in the native oxide at the silicon surface. Using realistic parameters, this model reproduces the observed voltage-dependent transition frequency and coupling strength of electron-on-neon qubits.

•Sep 22, 2026•0 citations

Electron on solid neon -- a new solid-state single-electron qubit platform

Xianjing Zhou, Gerwin Koolstra, Xufeng Zhang +8 more

The promise of quantum computing has driven a persistent quest for new qubit platforms with long coherence, fast operation, and large scalability. Electrons, ubiquitous elementary particles of nonzero charge, spin, and mass, have commonly been perceived as paradigmatic local quantum information carriers. Despite superior controllability and configurability, their practical performance as qubits via either motional or spin states depends critically on their material environment. Here we report our experimental realization of a new qubit platform based upon isolated single electrons trapped on an ultraclean solid neon surface in vacuum. By integrating an electron trap in a circuit quantum electrodynamics architecture, we achieve strong coupling between the motional states of a single electron and microwave photons in an on-chip superconducting resonator. Qubit gate operations and dispersive readout are used to measure the energy relaxation time $T_1$ of $15~\mu$s and phase coherence time $T_2$ over 200 ns, indicating that the electron-on-solid-neon qubit already performs near the state of the art as a charge qubit.

•Jun 18, 2021•1 citation

Dispersive Microwave Sensing for Quantum Computing with Floating Electrons

Yiran Tian

In this dissertation, resonator-based readout techniques were developed for floating electrons as qubits on cryogenic substrates, using two platforms: electrons on liquid helium and electrons on solid neon. In addition, a cryogenic microwave source was developed to enable low-noise measurement for qubit readout.

quant-pharXiv:2601.21313•Jan 30, 2026•0 citations

Solid neon as a noise-resilient host for electron qubits above 100 mK

Xinhao Li, Christopher S. Wang, Brennan Dizdar +7 more

Abstract Cryogenic solid neon has recently emerged as a pristine solid host for single electron qubits. At ~10 mK temperatures, electron-on-solid-neon (eNe) charge qubits have exhibited exceptionally long coherence times and high operation fidelities. To advance this platform towards a scalable quantum information architecture, systematic characterization of its noise feature is imperative. Here, we show the remarkable resilience of solid neon against charge and thermal noises when eNe qubits are operated away from the charge-insensitive sweet-spot and at elevated temperatures. Without optimizing neon growth, the measured charge (voltage) noise on solid neon is already orders of magnitude lower than that in most stringently grown semiconductors, rivaling the best records to date. Up to 400 mK, the eNe charge qubits operated at ~5 GHz can maintain their echo coherence times over 1 microsecond. These observations highlight solid neon as an ideal host for quantum information processing at higher temperatures and larger scales.

arXiv:2502.01005•Nature Electronics•Apr 29, 2026•1 citation

Deterministic single-electron trapping on solid neon using engineered dielectric surface geometry

Kundan Surse, Eric Helgemo, Andrew Palmer +5 more

Levitating electron qubit on the surface of solid neon has recently emerged as a promising and intrinsically noise-resilient platform for quantum information processing. Their ultra-clean, inert environment suppresses conventional decoherence pathways associated with lattice disorder, charge traps, and nuclear-spin baths that limit coherence in semiconductor qubits. Yet, uncontrolled surface features such as bumps, valleys, and electrode-defined gaps can bind electrons unintentionally, contributing charge noise and inducing spin-orbit coupling mediated decoherence. To address this challenge, we propose an engineered interface in which a dielectric layer is deposited beneath the solid neon to provide an atomically smooth template, eliminating surface-roughness induced trapping. By selectively etching this dielectric layer at desired qubit locations, deterministic potential minima can be engineered to reliably capture electrons while suppressing unwanted surface bound states. We perform large-scale Schrodinger and Poisson simulation to compare the existing and proposed strategies of electron trapping on neon, obtaining good agreement with recent experimental measurements.

quant-pharXiv:2607.13448•Jul 16, 2026•0 citations
Electrons trapped above cryogenic substrates such as liquid helium and solid neon form exceptionally clean physical systems, since they reside in vacuum and are largely isolated from environmental noise. A recent breakthrough has been the realization of charge qubits using electrons on solid neon surfaces, with coherence times reaching T2 = 2T1 ≈ 100 µs. In this article, we describe in detail the preparation of cryogenic substrates, electron deposition and the measurement of electron mobility. We further discuss the differences in surface morphology between helium and neon, their impact on mobility and qubit performance, and emphasize the necessity of systematic surface characterization as a means to optimize cryogenic substrate preparation and electron deposition.
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.
Electrons floating on condensed noble-gas substrates form a remarkably clean material system that is minimally influenced by the underlying host material, and recent experiments have explored their potential as a qubit platform. In particular, single electrons floating on solid neon thin films have attracted significant interest because they exhibit long coherence times when probed with superconducting circuits at frequencies around 6 GHz. Surprisingly, however, the energy spectrum of these qubits resembles that of a two-level-system defect more than the spectrum expected from the Coulomb potential defined by the bias electrodes. In this thesis, I first review floating-electron systems and the experimental methods used to probe their quantum states. I then show that electron-on-neon qubits with transition frequencies of a few GHz are observed only on neon films deposited on silicon surfaces, and not on neon films deposited on sapphire. Motivated by this observation, I propose a model in which a floating electron on the neon surface interacts with fixed positive charge defects in the native oxide at the silicon surface. Using realistic parameters, this model reproduces the observed voltage-dependent transition frequency and coupling strength of electron-on-neon qubits.
The promise of quantum computing has driven a persistent quest for new qubit platforms with long coherence, fast operation, and large scalability. Electrons, ubiquitous elementary particles of nonzero charge, spin, and mass, have commonly been perceived as paradigmatic local quantum information carriers. Despite superior controllability and configurability, their practical performance as qubits via either motional or spin states depends critically on their material environment. Here we report our experimental realization of a new qubit platform based upon isolated single electrons trapped on an ultraclean solid neon surface in vacuum. By integrating an electron trap in a circuit quantum electrodynamics architecture, we achieve strong coupling between the motional states of a single electron and microwave photons in an on-chip superconducting resonator. Qubit gate operations and dispersive readout are used to measure the energy relaxation time T1T_1T1​ of 15 μ15~\mu15 μs and phase coherence time T2T_2T2​ over 200 ns, indicating that the electron-on-solid-neon qubit already performs near the state of the art as a charge qubit.
Abstract Cryogenic solid neon has recently emerged as a pristine solid host for single electron qubits. At ~10 mK temperatures, electron-on-solid-neon (eNe) charge qubits have exhibited exceptionally long coherence times and high operation fidelities. To advance this platform towards a scalable quantum information architecture, systematic characterization of its noise feature is imperative. Here, we show the remarkable resilience of solid neon against charge and thermal noises when eNe qubits are operated away from the charge-insensitive sweet-spot and at elevated temperatures. Without optimizing neon growth, the measured charge (voltage) noise on solid neon is already orders of magnitude lower than that in most stringently grown semiconductors, rivaling the best records to date. Up to 400 mK, the eNe charge qubits operated at ~5 GHz can maintain their echo coherence times over 1 microsecond. These observations highlight solid neon as an ideal host for quantum information processing at higher temperatures and larger scales.
Levitating electron qubit on the surface of solid neon has recently emerged as a promising and intrinsically noise-resilient platform for quantum information processing. Their ultra-clean, inert environment suppresses conventional decoherence pathways associated with lattice disorder, charge traps, and nuclear-spin baths that limit coherence in semiconductor qubits. Yet, uncontrolled surface features such as bumps, valleys, and electrode-defined gaps can bind electrons unintentionally, contributing charge noise and inducing spin-orbit coupling mediated decoherence. To address this challenge, we propose an engineered interface in which a dielectric layer is deposited beneath the solid neon to provide an atomically smooth template, eliminating surface-roughness induced trapping. By selectively etching this dielectric layer at desired qubit locations, deterministic potential minima can be engineered to reliably capture electrons while suppressing unwanted surface bound states. We perform large-scale Schrodinger and Poisson simulation to compare the existing and proposed strategies of electron trapping on neon, obtaining good agreement with recent experimental measurements.