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Chicago Quantum Profile: Alex High

UChicago quantum professor makes light his life’s work

Written by Meredith Fore

When Alex High was growing up in rural West Virginia, he and his father would often go outside to look at the stars, discussing physics theories like quantum mechanics and relativity. It seems fitting that his career led him to a subject where those theories elegantly intersect: light.

“I was really drawn to the question: how do you control light?” he said. “Not just with big things like lenses and mirrors, but how do you actively control or structure light at the smallest possible dimensions?”

High has been a professor at the Pritzker School of Molecular Engineering at the University of Chicago for almost five years. His research focuses on the delicate manipulation of light at very small scales—a useful capability for advanced technology such as quantum communication or quantum sensing.

Quantum communication and networking technologies rely on the concept of quantum entanglement, where the states of two quantum objects are deeply dependent on one another. This dependence can enable communication between the two parties in possession of the entangled objects, as long as the quantum entanglement is maintained over the distance between them. Particles of light, called photons, can be used to create and maintain this quantum entanglement.

“There's a lot of research in the broader quantum technology community into how to entangle quantum states at large distances,” High said. “To do this effectively, we use photons to basically transmit entanglement, but you need to have complete control over them to be able to manipulate their interactions with individual quantum systems. So we structure our devices to control those photons such that they give us much more efficient connections.”

High says the work involves a lot of materials science, and a lot of experimentation with different combinations of materials to develop new approaches and new ways of controlling light’s physical properties. Through their collaboration with the U.S. Department of Energy’s Argonne National Laboratory, High and his group are actually able to grow their own diamonds. This allows them to fabricate novel materials and devices that are typically very hard to build, such as diamond thin films. In these thin films, light can be carefully routed around the diamond similar to how electrons are routed in circuits.  “Having the capabilities at Argonne with the Quantum Foundry is a gigantic local advantage, and we're trying to use that to realize the next generation of devices,” he said.

High’s work also directly relates to the field of quantum sensing: many quantum sensors emit photons to announce that they’ve detected something. Catching and carefully measuring the properties of these emitted photons is how researchers can achieve uniquely precise measurements of magnetic fields, cosmic particles, or miniscule vibrations. At UChicago, his group collaborates with the National Science Foundation Quantum Leap Challenge Institute for Quantum sensing for Biophysics and Bioengineering (QUBBE), helping to create quantum sensing devices that could be used in medicine or drug development.

“That’s the most exciting thing for me about quantum technology,” High said, “actually building these quantum sensors that can give you an unprecedented look at the nanoscale of really important biological or pharmaceutical systems. It might be one of the less prominent areas of quantum technologies compared to networking and computing, but I think it also has some of the highest potential societal value in terms of what it can potentially tell us about the world.”

Outside of academic research, High pursues the outdoor recreation activities he enjoyed in his youth, such as backpacking, swimming, and fishing. He also likes to dabble in a much different science: beer brewing. At its heart, he says, it requires the same kind of experimental approach as his quantum research.

“There are so many different ways you can control the process to get different flavor profiles, aromas, consistencies, and alcohol content. I love that aspect of it,” he said. “It's all about constructing recipes and ‘fabrication processes’ to get the desired beer at the end of the day.”