Incoming Undergrad Is Published in PRL

Amith Varambally of Vestavia Hills, Alabama, comes to Caltech as a first-year undergraduate student in fall 2023 already a co-author of a journal article related to his work as a high school intern at MIT in summer 2022.

It is uncommon for undergraduates to publish in STEM journals. Still less common is to see a high school student appearing as a co-author in the pages of an esteemed physics journal. This is the rare achievement of incoming undergrad Amith Varambally. "I didn't know what to expect when I set foot in Boston last summer, and I certainly never expected to be a co-author in a Physical Review Letters paper," says Varambally.

As a rising senior in high school, Varambally applied to the Research in Science and Engineering Program at Boston University and was placed in the Francis Bitter Magnet Laboratory at MIT under the direction of Jagadeesh Moodera, a senior research scientist. Varambally and his fellow intern Ourania Glezakou-Elbert, then a rising senior from Richland, Washington, promptly set to work learning about the physics behind superconducting diodes.

"Conventional diodes are devices that allow electrical current to flow easily in one direction but not so easily in the opposite direction," Varambally explains. "They operate like switches and are the building blocks of modern circuits. Diode-like devices known as transistors are packed by the billions onto semiconductor chips. They're in everything from your phone to your computer-all modern electronics."

The primary disadvantage of conventional diodes is that they lose immense amounts of energy through heat dissipation due to electrical resistance and through the energy needed to cool these systems. "These losses add up," says Varambally, "especially in the massive data centers and cloud-computing servers companies like Google or Amazon use. Hundreds of terawatt-hours of energy are lost annually, and the energy demand is rising."

Finding a superconducting material that could act as a diode is a "long-sought-after prize," says Varambally, "because if you cool superconductors below a threshold temperature-called the critical temperature-they lose all their electrical resistance. This could make for far more efficient circuits than those found in modern electronics."

Superconductors, Varambally explains, have several interesting properties. "With a molecular-beam epitaxy system, super-thin samples can be made on the scale of nanometers. After further fabrication, if you apply an external magnetic field, just a tiny field, you can achieve a polarity-dependent critical current-characteristic diode behavior."

The diode that Moodera, his colleagues, and his interns (including Varambally and Glezakou-Elbert) produced at MIT is "about 1,000 times thinner than the diameter of a human hair," according to an MIT press release, and "is easily scalable. Millions could be produced on a single silicon wafer."

"I was already interested in physics, but I wanted the experience of doing research and not just learning through textbooks," says Varambally. "The internship at MIT was just a great experience all around. From the people I met to the experience of doing the research to the discussions we had, I now have the platform to do more research. It's been really inspiring."

Once the internship confirmed Varambally's desire to become a physicist, "Caltech was naturally at the top of my list," he says. "Between the rigorousness of the physics program, the world-renowned research that goes on here, and the tremendous opportunities to do research and explore different fields of physics through summer research fellowships for undergraduates, it was an obvious choice."

Varambally is especially excited to explore different fields within physics at Caltech, from condensed matter and nuclear physics to particle physics, within an atmosphere conducive to research and surrounded by people "who are super interested in STEM."