“Unexplored levels” uncovered in flatland fractional quantum Hall effect electrons

New research into the 2-dimensional “flatland” where the rules of physics are tipped on their heads has led to the discovery of unexpected, and potentially useful, phenomena.

In rare cases, particles like electrons can have a fraction of their usual electrical charge – an effect known as the fractional quantum Hall effect.

The new study, published in Communications Physics, can “push the boundaries” of studies into the fractional quantum Hall effect according to co-author Ramesh G. Mani.

“Think of the traditional study of fractional quantum Hall effects as exploring the ground floor of a building,” explains Mani, a physics professor at the Georgia State University (GSU) in the US. “Our study is about looking for and discovering the upper floors – those exciting, unexplored levels – and finding out what they look like. Surprisingly, with a simple technique, we were able to access these upper floors and uncover complex signatures of the excited states.”

Mani likens the behaviour of particles in flatland to having “multiple personalities and can exhibit a context-dependent personality on demand”.

A semiconductor device made of alternating layers of gallium arsenide (GaAs) and aluminium gallium arsenide (AlGaAs) with a current applied helps create electrons in a flatland.

The team studied flatland electrons at conditions close to absolute zero (-273.15°C) and a magnetic field nearly 100,000 times stronger than that of the Earth was applied.

For the first time, the researchers reported fractional quantum Hall effect states splitting unexpectedly to create new states, revealing entirely new states of matter.

They say the findings have implications for future studies into fraction quantum Hall phenomena and technological developments. The work could be used in future technologies which transform data processing and energy efficiency.

Like the GSU experiment, the fractional quantum Hall effect usually requires an extremely large magnetic field but has recently been observed in graphene without an external magnetic field.