Physicists find signs of a time crystal

May 2, 2018 by Jim Shelton, Yale University
Yale physicists looked for a signature of a discrete time crystal within a crystal of monoammonium phosphate. Credit: Michael Marsland/Yale University

Yale physicists have uncovered hints of a time crystal—a form of matter that "ticks" when exposed to an electromagnetic pulse—in the last place they expected: a crystal you might find in a child's toy.

The discovery means there are now new puzzles to solve, in terms of how form in the first place.

Ordinary crystals such as salt or quartz are examples of three-dimensional, ordered spatial crystals. Their atoms are arranged in a repeating system, something scientists have known for a century.

Time crystals, first identified in 2016, are different. Their atoms spin periodically, first in one direction and then in another, as a pulsating force is used to flip them. That's the "ticking." In addition, the ticking in a time crystal is locked at a particular frequency, even when the pulse flips are imperfect.

Scientists say that understanding time crystals may lead to improvements in atomic clocks, gyroscopes, and magnetometers, as well as aid in building potential quantum technologies. The U.S. Department of Defense recently announced a program to fund more research into time crystal systems.

Yale's new findings are described in a pair of studies, one in Physical Review Letters and the other in Physical Review B. The studies represent the second known experiment observing a telltale signature for a discrete time crystal (DTC) in a solid. Previous experiments led to a flurry of media attention in the past year.

Yale researchers Jared Rovny, left, Robert Blum, center, and Sean Barrett, right, made the discovery. Credit: Yale University
"We decided to try searching for the DTC signature ourselves," said Yale physics professor Sean Barrett, principal investigator for the two new studies. "My student Jared Rovny had grown monoammonium phosphate (MAP) crystals for a completely different experiment, so we happened to have one in our lab."

MAP crystals are considered so easy to grow that they are sometimes included in crystal growing kits aimed at youngsters. It would be unusual to find a time crystal signature inside a MAP crystal, Barrett explained, because time crystals were thought to form in crystals with more internal "disorder."

The researchers used nuclear magnetic resonance (NMR) to look for a DTC signature—and quickly found it. "Our crystal measurements looked quite striking right off the bat," Barrett said. "Our work suggests that the signature of a DTC could be found, in principle, by looking in a children's crystal growing kit."

Another unexpected thing happened, as well. "We realized that just finding the DTC signature didn't necessarily prove that the system had a quantum memory of how it came to be," said Yale graduate student Robert Blum, a co-author on the studies. "This spurred us to try a time crystal 'echo,' which revealed the hidden coherence, or quantum order, within the system," added Rovny, also a Yale graduate student and lead author of the studies.

Barrett noted that his team's results, combined with previous experiments, "present a puzzle" for theorists trying to understand how time crystals form.

"It's too early to tell what the resolution will be for the current theory of discrete crystals, but people will be working on this question for at least the next few years," Barrett said.

Explore further: Walking crystals may lead to new field of crystal robotics

More information: Jared Rovny et al. Observation of Discrete-Time-Crystal Signatures in an Ordered Dipolar Many-Body System, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.120.180603

Jared Rovny et al. P31 NMR study of discrete time-crystalline signatures in an ordered crystal of ammonium dihydrogen phosphate, Physical Review B (2018). DOI: 10.1103/PhysRevB.97.184301

Related Stories

Walking crystals may lead to new field of crystal robotics

February 23, 2018

Researchers have demonstrated that tiny micrometer-sized crystals—just barely visible to the human eye—can "walk" inchworm-style across the slide of a microscope. Other crystals are capable of different modes of locomotion ...

Superior crystals grown from levitating droplets

December 6, 2016

Crystals that don't experience mechanical stress during growth have superior quality. Levitating liquid metal is the idea behind the project 'Perfecting metal crystals' led by the University of Twente in the Netherlands.

Microseeding: A new way to overcome hemihedral twinning?

December 15, 2016

Twinning is a crystal-growth disorder in which the specimen is composed of distinct domains whose orientations differ but are related in a particular, well-defined way. Twinning, which is a known problem in protein crystallography, ...

Fluorescent crystal mystery solved

August 31, 2017

A decades-old mystery of why a naturally-occurring organic crystal fluoresces blue under ultra-violet light, yet when grown under laboratory conditions fluoresces with an intense green colour, has been solved by scientists ...

Recommended for you

How bacterial communities transport nutrients

December 12, 2018

Under threat of being scrubbed away with disinfectant, individual bacteria can improve their odds of survival by joining together to form colonies, called biofilms. What Arnold Mathijssen, postdoctoral fellow in bioengineering ...

New method gives microscope a boost in resolution

December 12, 2018

Scientists at the University of Würzburg have been able to boost current super-resolution microscopy by a novel tweak. They coated the glass cover slip as part of the sample carrier with tailor-made biocompatible nanosheets ...

Copper compound as promising quantum computing unit

December 12, 2018

Quantum computers could vastly increase the capabilities of IT systems, bringing major changes worldwide. However, there is still a long way to go before such a device can actually be constructed, because it has not yet ...

4 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

AmritSorli
1 / 5 (5) May 03, 2018
time has only the mathematical existence and cannot be a crystal.....https://www.neuro...1221/961
Da Schneib
4.6 / 5 (9) May 03, 2018
Dude, they're measuring time crystals in the lab. Next you're going to tell us air has only mathematical existence.

Then there's the whole clock thing. You know, those funny round things they put up on walls with the hands that point to numbers. You might have seen some of those somewhere or other.
Varade
not rated yet May 03, 2018
It seem that all amphidynamic crystals/framework can have time crystal like properties.
antialias_physorg
1 / 5 (1) May 05, 2018
time has only the mathematical existence and cannot be a crystal

Maybe you should look up what a 'time crystal' actually is before making such dumb statements?
Because I'm pretty sure it isn't even remotely what you think it is.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.