Electron Bubbles in Helium Enable Quantum Control

Researchers have demonstrated that single electrons trapped in helium bubbles can serve as quantum nodes, enabling precise manipulation with mid-infrared lasers. This breakthrough could advance quantum networking by providing a simple, tunable platform for quantum information processing.

In condensed helium-4, excess electrons form self-confined bubbles 1-2 nm in radius, creating natural quantum wells. These electron bubbles interact resonantly with mid-infrared photons, with transition wavelengths tunable from 3 to 12 μm by adjusting pressure. Using femtosecond lasers with optical parametric amplifiers, researchers can drive these electrons into Rabi oscillations between ground and excited states, preparing arbitrary quantum superpositions.

The system shows remarkable versatility. Single electrons in slot-waveguide cavities exhibit vacuum Rabi oscillations with microsecond lifetimes, while two electrons naturally entangle through cavity coupling. The entanglement persists for nanoseconds, with concurrence reaching up to 0.6 depending on cavity loss rates. This electron-in-helium platform offers unique opportunities for studying nonequilibrium quantum dynamics in quantum matter.

Reference: Jin, D. et al. (2019). Quantum optics of single electrons in quantum liquid and solid helium-4. arXiv:1905.02654v2