EeroQ traps single electrons on liquid helium for qubits
A startup called EeroQ has published research demonstrating how to trap individual electrons floating on liquid helium, proposing it as a foundation for scalable quantum computing qubits. The technique leverages old physics to create isolated electron spins with potentially excellent coherence. Experts suggest this could enable rapid scaling using standard manufacturing processes.
Quantum computing continues to evolve with new approaches, even as established technologies advance. EeroQ, a company developing novel qubit systems, recently published a paper in Physical Review X detailing the physics behind trapping lone electrons on liquid helium. This method, first demonstrated half a century ago, positions electrons above a dielectric helium surface, where an image charge binds them without chemical interaction.
Johannes Pollanen, EeroQ's chief scientific officer, explained the process: "If you bring a charged particle like an electron near the surface, because the helium is dielectric, it'll create a small image charge underneath in the liquid." Liquid helium, a superfluid that flows without viscosity, remains stable up to 4 Kelvin—far warmer than the extreme cooling needed for many other qubits. Experiments used silicon chips with channels to guide electrons from a tungsten filament-loaded basin into electromagnetic traps formed by superconductive plates.
By adjusting trap walls, researchers reduced trapped electrons to zero, one, or two, distinguishing states via a resonator's frequency shift between flanking electrodes. A single electron can then be held indefinitely. The paper positions this as a "promising candidate for exploring mobile qubit architectures," focusing on electron spin for qubit storage.
Pollanen highlighted advantages: "The spin coherence of the electron is going to be fantastic," superior to silicon-based systems due to isolation in vacuum above helium. Using standard CMOS technology, chips could host "tens of thousands, hundreds of thousands, millions of qubits" with compact wiring for digital control. Qubits would encode information in pairs of opposing-spin electrons, mitigating decoherence during movement. Prior work showed electrons movable over a kilometer, enabling entanglement by shuttling them for interactions.
While unproven at scale, the physics offers an intriguing path for quantum processors.