The team was able to access properties of the crystal in its fragile quantum state using light. First predicted nearly a century ago, the Wigner crystal is a solid phase of electrons that forms a organized crystal-like lattice structure at low densities. So, a team of researchers led by Tomasz Smoleński, assistant professor at the University of Basel, probed the crystal using light. Hidden quantum behaviour The research team cooled a single layer of tungsten diselenide to temperatures just above absolute zero and illuminated it using light. To make sense of their find, the researchers also needed a strong theory of what was happening inside the Wigner crystal.