Jay Vaishnav

"What you can do using cold atoms and light is mimic real physical systems that you may not be able to see in real life."

Assistant professor of physics and astronomy

Strange things can happen in the world of quantum physics. Erwin Schrödinger, for example, famously described a thought experiment in which a cat would be both dead and alive at the same time, according to the rules of quantum mechanics. Schrödinger also predicted in 1930 that relativistic electrons oscillate — or jiggle back and forth — near the speed of light. The phenomenon, called Zitterbewegung for the German word for "trembling motion," has never been observed.

"This jittering motion is a very fundamental property of the dynamics of relativistic particles, so people have been trying to see it ever since," says Assistant Professor of Physics Jay Vaishnav. "There has been a lot of controversy back and forth as to whether it even really exists."

Vaishnav, along with her colleagues at the National Institute of Standards and Technology (NIST) in Gaithersburg, Md., devised a clever way to mimic the jittering behavior in a different system. It turns out that ultracold atoms behave in unusual ways, and can be used to simulate the quantum phenomena.

"What you can do using cold atoms and light is mimic real physical systems that you may not be able to see in real life," she says.

Vaishnav and her NIST collaborators have also devised a way to use ultracold atoms to create the long-sought spintronic transistor. The drive to make smaller and smaller electronics has reached the size limits of traditional transistors, which use electrical charge to carry information. In 1989, a duo of physicists predicted that using electron's spin, in addition to their charge, could allow more information to be carried in smaller spaces, and using less power. Nobody, however, has been able to build a physical model of such a "spintronic" transistor.

"The spintronic transistor is simple to design in principle but in practice materials are dirty, and they are impure, and it's hard to put in electrons of a particular spin," Vaishnav says. "So if you can design something with the exact same behavior using cold atoms, maybe you don't run into those problems."

Don't look, however, for fancy lasers or a supercooling apparatus in Vaishnav's office. She is a theoretical physicist, which means she spends her days manipulating equations, not atoms. Her ongoing collaboration with NIST allows for a rich cross-fertilization between the Institute's experimental work and her theoretical approach.

Vaishnav was attracted to Bucknell for its physics department, which has active research programs in atomic physics, nonlinear dynamics, and condensed matter physics. As a self-described city slicker, however, she was initially uncertain about the small-town setting. One visit overcame those doubts.

"Shortly after I arrived in Lewisburg, I found myself standing out on the quad in melting snow, looking out at the mountains," she says. "The hour struck, the chapel bells started ringing and I said to myself, 'Wow, this is what a college should be.' Standing there all by myself in a place I'd never seen before, I had the oddest feeling that I'd come home."

Posted Sept. 22, 2009