Water in a pot, when heated, doesn't boil: it turns into ice. That's roughly how ultracold atoms behave in an optical lattice — a light-based crystalline grid that holds atoms in place. Scientists simulated this system on a computer to understand how order changes as temperature rises.
At zero temperature, the system can be a superfluid (atoms move coherently, like a single wave), a Mott insulator (each atom is confined to its own cell), a supersolid (a combination of superfluidity and crystalline order), or a charge density wave (atoms occupy every other cell, forming a pattern). The transition between superfluidity and the charge density wave is sharp, like a light switch, and is accompanied by a region of phase coexistence.
If instead you start with a charge density wave and heat it, the order simply melts away smoothly, with no revival of superfluidity. At low temperatures, the system lingers in a metastable state, like supercooled water that doesn't freeze until you shake it. But at high temperatures, metastability disappears, and thermal energy itself arranges the atoms into a crystal.
This result reminds us that heat is not always a destroyer. Sometimes it helps the system find a more ordered state that it never suspected existed at low temperatures.
A similar effect is observed in some alloys: upon heating, they become more ordered, although heat usually destroys the crystal lattice.