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Deborah Jin Keeps It Cool with Quantum Mechanics

The 2004 Scientific American 50 researcher of the year continues to tweak matter at the edge of known physics to reveal strange and potentially useful properties
deborah jin, fermionic condensate, ultracold gas cloud, quantum mechanics



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Editor's Note: In mid-May, Scientific American will announce the winners of this year's Scientific American 10. Every Monday, starting April 13, we will profile a previous Scientific American 50 winner.

Year in Scientific American 50:
2004

Recognized for: Creating a novel state of matter that may help improve our understanding of superconductors. These are materials in which all resistance to an electrical current disappears at temperatures ranging from near absolute zero to as "warm" as around –170 degrees Fahrenheit (–112 degrees Celsius). Someday, superconductors could make for incredibly efficient power lines and electronic devices, but the development of such practical, room-temperature versions relies on a better understanding of the quantum mechanical properties of their far colder cousins.

To do that, scientists would like to get subatomic particles into arrangements that mimic superconductors. That's been a struggle: It took more than 70 years for researchers to coax frigid bosons—which, along with fermions, are the basic particles that comprise all known visible matter in the universe—into an arrangement dubbed a Bose-Einstein condensate, named for physicists Albert Einstein and Satyendra Nath Bose who predicted it in 1924.

Then, in late 2003, National Institutes of Standards and Technology physicist Deborah Jin's team used lasers and magnetic fields to steady and chill potassium atoms until they formed the first ever so-called fermionic condensate. In both kinds of condensates, the atoms share the same quantum state and behave identically. In this way, the condensate state of matter is analogous to what happens in superconductors, where fermionic electrons couple up and overcome their like-charge repulsions to flow freely, Jin says.

What's happened to her work: "We're still working on it," says Jin, who is also a physics professor at the University of Colorado at Boulder (U.C.B.). She and her colleagues aren't actively pursuing applications for their findings, Jin says. But big things may await her as the creator of the fermionic condensate, as Scientific American suggested in 2004: "The makers of the earlier Bose–Einstein condensate have already claimed a Nobel Prize for their accomplishment, and Jin seems a sure bet to eventually do the same."

What she is doing now:
Jin is still keeping it cool in her continuing quantum mechanical research—but this time she's upped the ante by superchilling molecules, rather than single atoms. "It's much harder to cool molecules than atoms," Jin notes.

She and fellow U.C.B. physicist Jun Ye recently succeeded in making a gas of ultracold polar molecules of potassium and rubidium near the temperature of the quantum regime where Jin previously observed a fermionic condensate. Polar molecules, as their name implies, have oppositely charged regions, allowing the molecules to "feel" and interact with each other without making direct contact, like magnets brought close together, Jin says. In this way, they are also somewhat like the electrons that naturally repel one another, except when brought into quantum harmony in a superconductive state.

One of Jin's goals in making these new, unnatural states of matter is to devise simple models to help illuminate the unpredictability of more complex quantum systems in the real world. "One of the nice things about ultracold atoms is that you can think of them as model systems where you can play with quantum mechanics," Jin says.

Her work gets into the territory of so-called many-body physics, which seeks to understand the emergent properties of multiply interacting particles. "The behavior that emerges when you have a lot of particles present is technologically relevant," Jin says, both for superconductors and quantum computing concepts. In summing up this quantum mystery of matter, she says: "What 100,000 atoms do is not 100,000 times what one atom does."

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