Electrons Floating on a Helium Sea
▼ Summary
– Several established quantum computing technologies are advancing with companies now focusing on engineering challenges after solving basic scientific problems.
– Some companies are still developing entirely new qubit technologies, betting on innovative approaches to enable a competitive comeback in the field.
– EeroQ’s qubit system uses single electrons floating on liquid helium, based on physics first demonstrated about 50 years ago.
– Electrons are bound to the helium surface by creating a weak positive image charge in the liquid, which attracts them without allowing absorption due to helium’s chemical inertness.
– This system operates at temperatures up to 4 Kelvin, which is less extreme than other technologies and provides a natural vacuum environment.
A select group of technologies currently leads the race to build a functional quantum computer. Firms have successfully engineered systems containing dozens to hundreds of qubits, steadily reducing error rates and transitioning from fundamental scientific hurdles to practical engineering issues. Even as the field matures, however, some ventures are still pioneering entirely new qubit platforms, wagering their success on an approach that could allow them to scale dramatically and emerge as a surprise frontrunner. A recent paper from one such company details the physics behind their system, which relies on individual electrons levitating above a film of liquid helium.
How exactly does one coax an electron to float on helium? According to Johannes Pollanen, the chief scientific officer at EeroQ, the company behind this innovation, the underlying principles are not new. Initial demonstrations of this phenomenon occurred about fifty years ago. He explained that when a charged particle like an electron approaches the helium surface, the dielectric nature of the liquid induces a faint image charge beneath it. This creates a small positive charge, weaker than the electron’s own charge, but enough to exert an attractive force. The electron becomes bound to this image of itself, drawn toward the positive charge but unable to merge with it. This is because helium is entirely chemically inert, offering no available states or spaces for the electron to occupy.
Achieving this setup first demands cryogenic conditions to liquefy the helium. The substance remains liquid at temperatures as high as 4 Kelvin, a range that does not necessitate the extreme refrigeration systems required by other qubit types like transmons. These cryogenic temperatures also create a natural vacuum environment, as nearly all other gases will condense and freeze onto the container’s walls.
(Source: Ars Technica)
