Bubble platform for gen-next soft quantum materials
doi:10.1038/nindia.2021.106 Published online 27 July 2021
Physicists have created nanosized bubbles in liquid helium that contain multiple electrons at extremely low temperatures1. This first ever experimental observation of 6 to 8 electrons-rich nano bubbles opens up a versatile platform for studying self-assembly at the intersection of the classical and quantum worlds, the researchers from Indian Institute of Science in Bangalore say.
Earlier, experiments have demonstrated the formation of bubbles containing single electrons in liquid helium. The scientists applied high voltage through a sharp tungsten tip that helped form a dense layer of electrons confined on the surface of liquid helium. The researchers, led by Ambarish Ghosh, observed that the electrons broke through microscopic dimples on the surface, forming nanosized electron bubbles inside the liquid.
Using sophisticated imaging techniques, they found the formation of few-electron bubbles. Each bubble contained six electrons. Applying ultrasound on the electron-rich liquid surface, they made bubbles inside the liquid helium. Each ultrasound-induced bubble contained eight electrons.
The subtle interplay of the short-range electron-helium repulsion and easy deformability of the bulk liquid formed the electron-containing bubbles, the researchers explain. The bubbles were stable for at least 15 milliseconds at 1.5 degrees Kelvin and could therefore allow fundamental studies of few-body quantum interactions under soft confinements, Ghosh said.
1. Yadav, N. et al. Bubbles in superfluid helium containing six and eight electrons: soft, quantum nanomaterial. Sci. Adv. 7, eabi7128 (2021) Doi: 10.1126/sciadv.abi7128