What comes to mind when you think of crystals? Perhaps it’s the dazzling ring on your hand, or the jagged-edged amethyst atop your mantel. But what about time crystals?
Two research teams from Harvard and the University of Maryland published research papers in the journal Nature revealing how they independently produced live crystals in the lab for the very first time.
First pinpointed as a mathematical eccentricity in 2012 by American theoretical physicist, mathematician, and Nobel laureate Frank Wilczek, time crystals occur when the period function of a three-dimensional spatial crystal reaches into the fourth dimension known as time.
Wilczek proposed that a time crystal was the “spontaneous emergence of a clock,” but the physics didn’t pan out, and so the idea went largely overlooked until 2015 when a group of researchers at Princeton University, led by Shivaji Sondhi, published research revealing how time crystals could be formed in the lab.
In a paper published online in the January edition of Physical Review Letters, Norman Yao, the University of California, Berkeley assistant professor of physics, described exactly how to make and measure the properties of a time crystal.
“Wouldn’t it be super weird if you jiggled the Jell-O and found that somehow it responded at a different period?” Yao said. “But that is the essence of the time crystal. You have some periodic driver that has a period ‘T’, but the system somehow synchronizes so that you observe the system oscillating with a period that is larger than ‘T’.”
This blueprint for such a crystal, along with research done at Microsoft’s Station Q laboratory at UC Santa Barbara, gave physicists at Harvard and the University of Maryland the tools they needed to independently create a time crystal in their laboratories using their own methods with the same theory.
The time crystal created by researchers at the University of Maryland implemented 10 ytterbium ions lined up in a row with electron spins interacting. In order to keep the ions out of equilibrium, the researchers hit them with a laser to force a magnetic field, and used another layer to partially flip the spins of the atoms. The sequenced was repeated many times. The spins interacting resulted in the atoms maintaining a stable, repetitive pattern of spin flipping, which defines a crystal.
The Harvard team created its time crystal using densely packed nitrogen vacancy centers in diamonds.
“Such similar results achieved in two wildly disparate systems underscore that time crystals are a broad new phase of matter, not simply a curiosity relegated to small or narrowly specific systems,” explained Phil Richerme from Indiana University in a perspective piece accompanying the paper.
“Observation of the discrete time crystal . . . confirms that symmetry breaking can occur in essentially all natural realms, and clears the way to several new avenues of research,” Richerme, who was not involved in the study, continued.
Such research is important given that it provides the very first example of non-equilibrium matter, which could ultimately lead to breakthroughs in our understanding of the world around us, and benefit advances in technology like quantum computing.