Charlie Wood writes:

It is a truth of both physics and everyday experience that things fall apart. Ice melts. Buildings crumble. Any object, if you wait long enough, gets mixed up with itself and its surroundings beyond recognition.

But beginning in 2005, a series of breakthroughs made this death march seem optional. In just the right quantum setting, any arrangement of electrons or atoms would stay put for all eternity — even uneven arrangements thrumming with activity. The finding flew in the face of the conventional wisdom that quantum phenomena were fragile things, observable only at extremely low temperatures. It also punched a hole in the foundations of thermodynamics, the venerable branch of physics that explains phenomena like heat and entropy as inevitable consequences of the interplay of vast swarms of particles.

The results came as a shock to physicists like Norman Yao, a graduate student at the time who is now a professor at Harvard University. “Holy hell,” he recalled thinking, using a stronger word than hell. “If this is true in an interacting, many-particle system, then statistical mechanics fails. Thermodynamics fails.”

The notion of a radical new quantum stability spread. It inspired theorists to conjure up a menagerie of new phases of quantum matter such as time crystals — systems that sustain a repeating behavior indefinitely without absorbing energy. And quantum engineers battling the skittishness of qubits to build quantum computers took heart at this indication that their fight was a winnable one.

“In a quantum computer you need to have memory of your initial conditions; otherwise you can’t do anything,” Yao said.

The accumulation of evidence peaked in 2014 with a rigorous mathematical proof that quantum patterns could indeed last forever.

In recent years, however, the promise of eternally stable quantum structures has itself begun to wobble. [Continue reading…]