An electron’s charge is normally fixed, like a coin you can’t break into pieces. But if electrons are cooled close to absolute zero and trapped in a two-dimensional layer under a powerful magnetic field, they organize into a collective state of “quasiparticles” that seem to hold only a fraction of an electron’s charge.

This state is known as the “fractional quantum Hall effect.” A small number of these states, known as “even-denominator states,” have drawn attention because some theories predict they could contain unusual quasiparticles called “non-Abelian anyons.”

Why are these interesting? Because their quantum properties make them candidates for storing and processing information in fault-tolerant (error-resistant) topological quantum computers.