Scientists Used a Diamond to Create a New Phase of Matter

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Here’s what you’ll learn when you read this story:

• Time crystals are quantum phases of matter that repeat across time rather than in space (like the atomic lattice of a crystal).

• Using a diamond as a quantum simulator, scientists created a rondeau time crystal, which exhibited both long-range temporal order and short-time disorder.

• While this discovery has no practical application yet, the researchers are confident that this process can be applied to other material beyond diamonds.

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Since their theoretical discovery in 2012, time crystals have been front-and-center in conversations about how to improve quantum computers. While diamond, ice, and any other solid you can think of has a crystal lattice structure that repeats in space (another name for them could be “space crystals”), time crystals, as their name suggests, oscillate in perpetual cycles across time. These crystals, the thinking goes, could form stable forms of quantum memory and error-free quantum circuits, drastically improving a quantum computer’s performance.

However, there is still a lot we don’t know about time crystals—we only got our first visual of how these things work earlier this year—but one thing we do know is that not all time crystals are the same. For example, there are discrete (externally driven) and continuous (self-sustained) time crystals, and time crystals can contain varying properties beyond just these two categories. Case in point, a new study published in the journal Nature Physics explores the concept of a rondeau time crystal, a new phase of matter that contains both long-range temporal order and short-time disorder, according to Phys.org.

“The motivation for this research stems from how order and variation coexist across art and nature,” Leo Moon, a Ph.D. student at University of California Berkeley and co-author of the study, told Phys.org. “Repetitive periodic patterns naturally arise in early art forms due to their simplicity, while more advanced music and poetry build intricate variations atop a monotonous background.”

In fact, one art form in particular inspired this new phase of matter’s name. A “rondo” (or rondeau, as the early French harpsichord composers wrote it) is a repeating theme with variations mixed throughout. The most famous example of a rondo is likely Mozart’s “Rondo alla Turca” (if the name doesn’t sound familiar, believe me, you’ve definitely heard it). Relating back to physics, Phys.org notes that typical crystal lattices can also contain both order and disorder—oxygen atoms, for instance, form a repeating lattice in ice, while the hydrogen nuclei are spread randomly throughout. “Ice has ordered oxygen positions but disordered hydrogen bonds, and that local randomness carries structural information” Moon said.

To explore this exotic temporal phase, the researchers relied on carbon-13 atoms in a diamond, which contain defects in the form of nitrogen atoms sitting next to empty spots in the lattice. These defects are known as “nitrogen-vacancy (NV) centers,” and when illuminated with lasers, these centers become spin polarized. With microwave pulses boosting the polarization were combined with “protective ‘spin-locking’ pulses with strategically timed polarization-flipping pulses,” Phys.org reports, Moon and his team created a rondeau crystal. Using ASCII (a character encoding standard), the researchers also successfully stored information in these timing pulses.

“Although our experiment focused on nuclear spins in a diamond, the underlying concept is immediately applicable to a wide swathe of quantum simulator platforms,” the authors wrote in the study. “Our experiments open a promising new avenue to investigate temporal order, demonstrating the long-lived stable coexistence of long-range temporal order and micromotion disorder at short timescales.”

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