Illustration of excitons arranging into a solid pattern in bilayer graphene. Credit: Cory Dean, Columbia University When everyday matter is cooled, it follows a familiar path. A gas becomes a liquid, and with further cooling, that liquid turns into a solid. Quantum matter does not always follow these rules. More than a century ago, scientists discovered that helium behaves in an unexpected way at extremely low temperatures. Instead of freezing, it transforms from a normal gas into a superfluid,