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Stirring-­p Atomtronics in a Quantum Circuit

Schematic of laser setup (red and blue beams) to create a flat, toroidal-shaped BEC (shown in yellow).

Researchers at the Joint Quantum Institute say they have used a superfluid atomtronic circuit to create a hysteresis.

Credit: Joint Quantum Institute

Researchers at the Joint Quantum Institute (JQI) have used a superfluid atomtronic circuit to create a hysteresis, which they say is the first time  hysteresis has been observed in an ultracold atomic gas.

"This effect is used in writing information to hard drives as well as other memory devices," says JQI researcher Stephen Eckel. "It's also used in certain types of sensors and in noise filters such as the Schmitt trigger."

The researchers observed hysteresis, which is an inherent natural property of a quantum fluid. When 400,000 sodium atoms are cooled to condensation, they form a type of quantum matter called a Bose-Einstein condensate (BEC). BECs have unusual collective properties, making them a superfluid, which is a type of matter that can flow persistently, undeterred by friction. The behavior results in the fluid flow or rotational velocity around the team's ring trap to become quantized, meaning it can only spin at certain specific speeds.

Controlling this hysteresis opens up new possibilities for building a practical atomtronic device. For example, researchers have developed specialized superconducting electronic circuits, called superconducting quantum interference devices, that are precisely controlled by magnetic fields.

From Joint Quantum Institute
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Abstracts Copyright © 2014 Information Inc., Bethesda, Maryland, USA


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