Heng Fan

Imagine a soloist trying to blend their voice with a choir. If the choir sings in unison, the soloist's voice stands out for a long time; but if the choir scatters across a wide range — from deep basses to ringing sopranos — the soloist dissolves almost instantly. In quantum physics, the role of such a choir is played by a thermal bath — a massive environment.

In 1963, a Tanzanian schoolboy named Erasto Mpemba noticed that hot ice cream freezes faster than cold. That paradox, named after him, long remained a subject of debate in classical thermodynamics. Now the quantum world offers its own version: a state with more strongly broken symmetry can recover it faster than a less broken one.

A quantum computer relies on two forces: entanglement (particles behaving as a single whole) and "magic"—a measure of how far a state is from familiar classical physics. But how these two resources relate as a many-particle system evolves in time has remained a puzzle. The authors approached the problem through time.