Ultracold atom waves may shed light on rogue ocean killers

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By precisely controlling the quantum behavior of an ultracold atomic gas, Rice University physicists have created a model system for studying the wave phenomenon that may bring about rogue waves in Earth’s oceans.

The research appears this week in Science. The researchers said their experimental system could provide clues about the underlying physics of rogue waves — 100-foot walls of water that are the stuff of sailing lore but were only confirmed scientifically within the past two decades. Recent research has found rogue waves, which can severely damage and sink even the largest ships, may be more common than previously believed.

By precisely controlling the quantum behavior of an ultracold atomic gas, Rice University physicists have created a model system for studying the wave phenomenon that may bring about rogue waves in Earth’s oceans.

The research appears this week in Science. The researchers said their experimental system could provide clues about the underlying physics of rogue waves — 100-foot walls of water that are the stuff of sailing lore but were only confirmed scientifically within the past two decades. Recent research has found rogue waves, which can severely damage and sink even the largest ships, may be more common than previously believed.

“We are interested in how self-attracting waves develop,” said lead scientist Randy Hulet, Rice’s Fayez Sarofim Professor of Physics and Astronomy. “Although our experiment is in the quantum domain, the same physics applies to classical waves, including rogue water waves.”

Hulet’s lab uses lasers and magnetic traps to cool tiny clouds of an atomic gas to less than one-millionth of a degree above absolute zero, temperatures far colder than the deepest reaches of outer space. At this extreme, quantum mechanical effects take center stage. Atoms can be made to march in lockstep, momentarily vanish or pair up like electrons in superconductors. In 2002, Hulet’s team created the first “soliton trains” in ultracold atomic matter. Solitons do not diminish, spread out or change shape as they move. In 2014, Hulet and colleagues showed that two matter wave solitons traveling in opposite directions in a trap would briefly wink out of existence rather than share space as they passed through one another.

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Image: The orange and yellow stripes in this composite image depict matter waves from different experimental runs in the Hulet Lab at Rice University. The stripes show how matter waves change due to rapid magnetic shifts that bring about modulational instability. The left line shows a matter wave before magnetic switching.  Subsequent images (to left) show how both repulsive to attractive fluctuations become amplified in the wave.  Clear signs of deviations from the initial solid shape can be seen in the third image, and the peaks and valleys in the far left image show how the wave morphs into a “soliton train,” a set of standing waves.  (Image courtesy of J. Nguyen / Rice University)