The Quest to Crystallize Time
Illumination with green light reveals a time crystal formed in a network of electron spins (red) within the defects of a diamond. [Courtesy: Georg Kucsko].
Time crystals are hypothetical structures that pulse without requiring any energy — like a ticking clock that never needs winding. The pattern repeats in time in much the same way that the atoms of a crystal repeat in space. The idea was so challenging that when Nobel prizewinning physicist Frank Wilczek proposed the provocative concept1 in 2012, other researchers quickly proved there was no way to create time crystals.
But there was a loophole — and researchers in a separate branch of physics found a way to exploit the gap. Monroe, a physicist at the University of Maryland in College Park, and his team used chains of atoms they had constructed for other purposes to make a version of a time crystal1 (see 'How to create a time crystal'). “I would say it sort of fell in our laps,” says Monroe.
And a group led by researchers at Harvard University in Cambridge, Massachusetts, independently fashioned time crystals out of 'dirty' diamonds2. Both versions, which are published this week in Nature, are considered time crystals, but not how Wilczek originally imagined. “It's less weird than the first idea, but it's still fricking weird,” says Norman Yao, a physicist at the University of California, Berkeley, and an author on both papers...
[Reprinted by permission from Nature Publishing Group]
1. J. Zhang, P.W. Hess, A. Kyprianidis, P. Becker, A. Lee, J. Smith, G. Pagano, I.-D. Potirniche, A.C. Potter, A. Vishwanath, N.Y. Yao & C. Monroe, "Observation of a discrete time crystal," Nature 543 (09 March 2017) doi:10.1038/nature21413.
2. S. Choi, J. Choi, R. Landig, G. Kucsko, H. Zhou, J. Isoya, F. Jelezko, S. Onoda, H. Sumiya, V. Khemani, C. von Keyserlingk, N.Y. Yao, E. Demler & M.D. Lukin, "Observation of discrete time-crystalline order in a disordered dipolar many-body system," Nature 543, (08 March 2017) doi:10.1038/nature21426.