Tag Archives: Chris Monroe

Formation of a time (temporal) crystal

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It’s a crystal arranged in time according to a March 8, 2017 University of Texas at Austin news release (also on EurekAlert), Note: Links have been removed,

Salt, snowflakes and diamonds are all crystals, meaning their atoms are arranged in 3-D patterns that repeat. Today scientists are reporting in the journal Nature on the creation of a phase of matter, dubbed a time crystal, in which atoms move in a pattern that repeats in time rather than in space.

The atoms in a time crystal never settle down into what’s known as thermal equilibrium, a state in which they all have the same amount of heat. It’s one of the first examples of a broad new class of matter, called nonequilibrium phases, that have been predicted but until now have remained out of reach. Like explorers stepping onto an uncharted continent, physicists are eager to explore this exotic new realm.

“This opens the door to a whole new world of nonequilibrium phases,” says Andrew Potter, an assistant professor of physics at The University of Texas at Austin. “We’ve taken these theoretical ideas that we’ve been poking around for the last couple of years and actually built it in the laboratory. Hopefully, this is just the first example of these, with many more to come.”

Some of these nonequilibrium phases of matter may prove useful for storing or transferring information in quantum computers.

Potter is part of the team led by researchers at the University of Maryland who successfully created the first time crystal from ions, or electrically charged atoms, of the element ytterbium. By applying just the right electrical field, the researchers levitated 10 of these ions above a surface like a magician’s assistant. Next, they whacked the atoms with a laser pulse, causing them to flip head over heels. Then they hit them again and again in a regular rhythm. That set up a pattern of flips that repeated in time.

Crucially, Potter noted, the pattern of atom flips repeated only half as fast as the laser pulses. This would be like pounding on a bunch of piano keys twice a second and notes coming out only once a second. This weird quantum behavior was a signature that he and his colleagues predicted, and helped confirm that the result was indeed a time crystal.

The team also consists of researchers at the National Institute of Standards and Technology, the University of California, Berkeley and Harvard University, in addition to the University of Maryland and UT Austin.

Frank Wilczek, a Nobel Prize-winning physicist at the Massachusetts Institute of Technology, was teaching a class about crystals in 2012 when he wondered whether a phase of matter could be created such that its atoms move in a pattern that repeats in time, rather than just in space.

Potter and his colleague Norman Yao at UC Berkeley created a recipe for building such a time crystal and developed ways to confirm that, once you had built such a crystal, it was in fact the real deal. That theoretical work was announced publically last August and then published in January in the journal Physical Review Letters.

A team led by Chris Monroe of the University of Maryland in College Park built a time crystal, and Potter and Yao helped confirm that it indeed had the properties they predicted. The team announced that breakthrough—constructing a working time crystal—last September and is publishing the full, peer-reviewed description today in Nature.

A team led by Mikhail Lukin at Harvard University created a second time crystal a month after the first team, in that case, from a diamond.

Here’s a link to and a citation for the paper,

Observation of a discrete time crystal by 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. Nature 543, 217–220 (09 March 2017) doi:10.1038/nature21413 Published online 08 March 2017

This paper is behind a paywall.

Quantum kind of day: metaphors, language and nanotechnology

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I had a bonanza day on the Nanowerk website yesterday as I picked up three items, all of which featured the word ‘quantum’ in the title and some kind of word play or metaphor.

From the news item, Quantum dots go with the flow,

Quantum dots may be small. But they usually don’t let anyone push them around. Now, however, JQI [Joint Quantum Institute] Fellow Edo Waks and colleagues have devised a self-adjusting remote-control system that can place a dot 6 nanometers long to within 45 nm of any desired location. That’s the equivalent of picking up golf balls around a living room and putting them on a coffee table – automatically, from 100 miles away.

There’s a lot of detail in this item which gives you more insight (although the golf ball analogy does that job very well) into just how difficult it is to move a quantum dot and some of the problems that had to be solved.

Next, A quantum leap for cryptography,

To create random number lists for encryption purposes, cryptographers usually use mathematical algorithms called ‘pseudo random number generators’. But these are never entirely ‘random’ as the creators cannot be certain that any sequence of numbers isn’t predictable in some way.

Now a team of experimental physicists has made a breakthrough in random number generation by applying the principles of quantum mechanics to produce a string of numbers that is truly random.

‘Classical physics simply does not permit genuine randomness in the strict sense,’ explained research team leader Chris Monroe from the Joint Quantum Institute (JQI) at the University of Maryland in the US. ‘That is, the outcome of any classical physical process can ultimately be determined with enough information about initial conditions. Only quantum processes can be truly random — and even then, we must trust the device is indeed quantum and has no remnant of classical physics in it.’

This is a drier piece (I suspect that’s due to the project itself) so the language or word play is in the headline. I immediately thought of a US tv series titled, Quantum Leap where, for five seasons, a scientist’s personality/intellect/spirit is leaping into people’s bodies, randomly through time. There are, according to Wikipedia, two other associations, a scientific phenomenon and a 1980s era computer. You can go here to pursue links for the other two associations. This is very clever in that you don’t need to have any associations to understand the base concept in the headline but having one or more association adds a level or more of engagement.

The final item, Scientists climb the quantum ladder,

An EU [European Union]-funded team of scientists from Cardiff University in the UK has successfully fired photons (light particles) into a small tower of semiconducting material. The work could eventually lead to the development of faster computers. …

The scientists, from the university’s School of Physics and Astronomy, said a photon collides with an electron confined in a smaller structure within the tower. Before the light particles re-emerge, they oscillate for a short time between the states of light and matter.

While I find this business of particles oscillating between two different states, light and matter, quite fascinating this particular language play is the least successful. I think most people will do what I did and miss the relationship between the ‘tower’ in the news item’s first paragraph and the ‘ladder’ in the headline. I cannot find any other attempt to play with either linguistic image elsewhere in the item.

Given that I’m  a writer I’m going to argue that analogies, metaphors, and word play are essential when trying to explain concepts to audiences that may not have your expertise and that audience can include other scientists. Here’s an earlier posting about some work by a cognitive psychologist, Kevin Dunbar, who investigates how scientists think and communicate.