Few electron bubbles (FEBs) in superfluid helium

Few electron bubbles (FEBs) in superfluid helium

Subject: Science and Technology

Context: Scientists at the Indian Institute of Science (IISc) have experimentally shown the existence of two species of few electron bubbles (FEBs) in superfluid helium for the first time.

Concept:

• The electron bubbles FEBs can serve as a useful model to study how the energy states of electrons and interactions between them in a material influence its properties. FEBs, are nano metre-sized cavities in liquid helium containing just a handful of free electrons. The number, state and interactions between free electrons dictate the physical and chemical properties of materials.
• An electron injected into a superfluid form of helium creates a single electron bubble (SEB) a cavity that is free of helium atoms and contains only the electron.
• The shape of the bubble depends on the energy state of the electron. There are also MEBs multiple electron bubbles that contain thousands of electrons.
• These FEBs were found to be stable for at least 15 milliseconds (quantum changes typically happen at much shorter time scales) which would enable researchers to trap and study them. FEBs form system that has both electron-electron interaction and electron-surface interaction

Studying FEBs, could help scientists

• better understand how some of these properties emerge when a few electrons present in a material interact with each other
• Provide insights into the self-assembly of soft materials, which can be important for developing next- generation quantum materials.
• scientists have only theoretically predicted the existence of FEBs so far, now experimentally observed FEBs for the first time and understood how they are created
• There are several phenomena that FEBs can help scientists decipher, such as turbulent flows in super fluids and viscous fluids, or the flow of heat in superfluid helium, superfluid helium also conducts heat efficiently at very low temperatures
• The defects in the system, called vortices. Since FEBs are present at the core of such vortices, can help in studying how the vortices interact with each other as well as heat flowing through the superfluid helium.