UCSB Physicist Receives $360,000 Air Force Grant to Study Ultracold Atoms

UCSB assistant professor of physics David Weld has received a $360,000 grant from the Air Force Office of Scientific Research (AFOSR) to continue his work with ultracold atoms. Weld is one of only 48 scientists and engineers — selected from a field of 220 applicants — to win grants, totaling $18 million.

According to Weld, he will pursue three main areas of study with the grant. The first is quantum simulation, or the use of ultracold atoms to study how quantum systems work.

“We have perfect control over these systems … you can prepare systems, the behavior of which is too complex to calculate, and then see what [they] do,” Weld said. “The hope of the field of quantum simulation is to draw analogies between these cold gases and real materials like superconductors, quantum magnets, which will enable advances in real materials.”

The second area of study concerns the use of ultracold atoms as a “force sensor” to study gravity at extremely small scales. Finally, the third objective is to investigate a new cooling technique to be used as a tool to help control experiments under study.

In order to pursue these objectives, Weld and his colleagues plan to use the grant money to construct a piece of equipment that enables the experiment to run at the extreme temperatures and conditions necessary.

“What we proposed to do in the grant was first to build a particular device and then to do a number of experiments and projects with it,” Weld said. “The device we’re going to build is an ultracold strontium apparatus, which will enable us to produce condensed and Fermi-degenerate gases of strontium.”

Weld hopes this work may lead, among other areas, to new insights in high-temperature superconductivity. Superconductors are materials with exactly zero electrical resistance when cooled below a certain critical temperature. This critical temperature is usually near absolute zero. For some experiments, however, the critical temperature is high enough to be reached with liquid nitrogen or similar methods (rather than other, more intensive techniques needed to approach absolute zero). This makes these “high-temperature” superconductors useful in industry, but according to Weld, physicists are still unsure how they actually work.

“One of the big holy grails in physics is to understand how high-temperature superconductivity works,” Weld said. “Nobody knows that, which is amazing, given that these materials have been around for 20 or 25 years and it’s not understood what the mechanism of superconductivity is. People have a lot of different theories but there’s no consensus and there’s a lot of confusion.”

Over the years, the critical temperature of superconductors has been increasing with new advances in technology.

“The critical temperature can get as high as a few hundred degrees Kelvin, typically only around 100 degrees Kelvin, and never around room temperature,” Weld said.

Additionally, scientists in the field have agreed that work on creating superconductors that operate at room temperature would be worthwhile, especially in industry.

According to Weld, the first step toward building such a device is in understanding how “high temperature” superconductors work.

Weld remains grateful to the UCSB physics community for their support in being awarded this grant and the AFOSR for selecting his project.

“UCSB has a great department, great environment,” Weld said. “The university offered me a lot of really great support in applying for these grants. I don’t think I would have gotten [the Air Force grant] without all the help from people here. I’m excited to be working with the Air Force, it’s an exciting area, and I’m looking forward to building up my lab here at UCSB. People should come by and talk to me if they’re interested in my research.”


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