Brendan Ray Builds Tool for Quantum Physics Research

Carnegie Mellon University student Brendan Ray is pushing the boundaries of physics research, creating tools that could deliver insights into quantum physics and bring scientists closer to more advanced superconductors.

“High energy and quantum physics are some of the most exciting topics in physics,” said Ray, a rising sophomore studying physics on the quantum physics track.

Ray worked with Ben Hunt, associate professor of physics and co-director of the Pittsburgh Quantum Institute (PQI). Hunt investigates ways to create superconductors, which can conduct electricity without losing energy. One of the challenges is that superconductors typically work at extremely low temperatures, often near absolute zero, where atoms stop moving.

Hunt and other researchers are investigating ways to develop structures that combine semiconductors and superconductors. Advancing these materials could accelerate the development of quantum computers, which can process multiple functions simultaneously instead of one at a time like traditional computers. To develop these materials, researchers need advanced semiconductor fabrication techniques.

“Certain properties of semiconductors are highly tunable, which is why they are used to make transistors,” Hunt said. “It would be exciting to take advantage of some of those properties in devices for quantum computing.”

Ray is building a photolithography stepper, a machine used widely in industrial manufacturing to pattern semiconductors. The system projects intricate patterns onto silicon chips with a UV-sensitive coating, enabling the chips to conduct electricity in specific ways. Because commercial lithography steppers can cost tens of thousands of dollars, Ray used documentation from The Hacker Fab at CMU, a student-run semiconductor fabrication facility, to guide the development of a more accessible machine.

“It’s more time-effective and more cost-effective to have a homemade lithography stepper,” Ray said. “It’s a creative way to do the nanofabrication process.”

The Hunt lab will use this machine to help construct Josephson junctions, devices engineered to exhibit superconducting behavior. A Josephson junction has a thin layer of semiconducting or insulating material sandwiched between two layers of superconductor. By testing different material combinations and structures, researchers hope to develop junctions that are capable of being superconductive at higher temperatures, bringing practical quantum technologies one step closer to reality.

“I first saw the capabilities of the homebuilt stepper a few years ago at the Hacker Fab demo, and I was amazed that they were able to do this,” Hunt said. “I dreamed about having one in my lab, and thanks in part to Brendan’s great ability and motivation, it is finally happening.”

Ray pursued summer research through the Department of Physics’ Robert W. Kraemer Fellowship, which gives a rising sophomore the opportunity to conduct summer research under a mentor. Gillian Ryan, teaching professor and director of undergraduate affairs for physics, said that Ray’s passion helped him earn the award.

“Brendan demonstrated a sophisticated grasp of this field by articulately discussing his academic interest in condensed matter physics in his application,” Ryan said. “He communicated that he is excited about both the specific scientific questions and the holistic growth that comes with being a research scientist.”

Ray said that the experience reinforced his interest in quantum physics. He plans to continue conducting research throughout his undergraduate career, building on the skills and knowledge he gained through the fellowship.

“It’s been a very cool experience,” Ray said. “Being able to build this tool myself has been very motivating. I would definitely like to do more research like this in the future.”