Scientists Discover a Strange New Phase of Matter Called ‘Time Crystals'
Two papers published simultaneously prove the existence of time crystals, in which atoms are aligned in time in a way that's analogous to the physical structure of diamonds or ice.
New research has confirmed the existence of a bizarre phase of matter once thought to be impossible — a quantum alignment known as a "time crystal."
The discovery may one day have important implications for quantum computers, which are super-powerful machines that perform exponentially faster than conventional computers by exploiting the rules of quantum dynamics.
At present, however, time crystals are more of a scientific oddity with no known real-world applications.
In normal crystals — such as gemstones, snowflakes, or salt — constituent atoms or molecules are arranged into highly ordered, repeating lattice structures in physical space.
In time crystals, however, atoms take on a repeating pattern in time, instead of space.
Time crystals were developed by zapping atoms with lasers to make them pulsate together, in a way similar to making the head of a drum vibrate when it is struck, or tapping Jell-O with a spoon to make it jiggle, according to one of the researchers involved in the discovery, Christopher Monroe of the University of Maryland.
"This is a very newfangled topic," Monroe said by phone from College Park, Maryland. "The easiest thing to do is to make an analogy to a spatial crystal. But instead of space, apply this to time."
Two teams of scientists, one including Monroe that was led by the University of Maryland, and the other led by Harvard University, simultaneously published papers confirming the existence of time crystals in laboratory environments this week in the scientific journal Nature.
When the idea of time crystals was first proposed in 2012 by Nobel Prize winner Frank Wilczek, other theorists proved the concept was physically impossible — at least, in the version that Wilczek originally envisioned, in which the time crystals existed in a state of equilibrium with their environment.
Part of the problem, in theory, was keeping the internal system of the time crystal from heating up infinitely, according to Monroe.
"That argument seemed iron-clad, but there was a loophole," Monroe said. "Here, we keep driving this system, and it doesn't heat up. That's the loophole. It doesn't heat up to infinity."
To build a time crystal, Monroe and his colleagues used a complex array of lasers, magnets, mirrors, and optical equipment.
"We took individual atoms and electro-magnetically trapped them, levitated them in a vacuum chamber so no air could hit them, and then we poked at them with laser beams," he said.
The team at Harvard took a different approach, sending lasers and microwaves through a black diamond, which was chosen because its one million impurities could in fact be utilized to create time crystals.
The time crystal breakthrough could potentially help quantum computers function with a greater degree of complexity and stability, or be used to construct special new kinds of quantum clocks, Monroe said.
"I would put this on the heap of research related to quantum computing," he said.
Traditional computing relies on transistors to form sentences out of strings of ones and zeroes. Quantum computers take advantage of special rules for tiny particles that allow for the superposition of different states — which, in theory, vastly expands the potential computational power of such a machine, because it's no longer stuck in a binary world.
But as quantum systems get strung together, they begin to behave more like objects in the non-quantum world, said Monroe — and lose the quantum effect that makes them powerful in the first place.
Time crystals may theoretically one day be used to help solve that problem by allowing particles to retain their quantum coherence even as the size of a quantum computer expands, Monroe said.
"This is sort of a way out, an end-run," he said. "It could allow you to maintain quantum purity in a big system."
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