Carolina remembers Zijie Yan, ‘master of light and matter’

Woodworking is a deeply reflective practice for Richard Superfine. He pulls materials from nature and shapes them into something meaningful.

The applied physical sciences professor teaches a first-year seminar course at Carolina called Tree. Timber. Totem that explores the intertwining of trees and human emotion. Each semester, Superfine asks students to create their own wooden totems — objects that represent family.

This semester, Superfine and his class will craft three benches in honor of associate professor Zijie Yan, who died in last year’s Aug. 28 shooting at Caudill Labs. The class will send one bench to Yan’s wife and two young daughters, and another will go to Yan’s parents. The third bench will stay on Carolina’s campus in Chapel Hill.

As former chair of the APS department, Superfine interviewed and hired Yan in 2019. He remembers Yan as calm, composed and insightful, someone who brought maturity and creativity to a young department.

“He was brave and asking hard questions, but he always had a kindness to him and a calmness,” Superfine said. “And I was so thrilled to bring him to UNC because I knew how he could contribute to the whole department. I know a good deal about his scholarship, and he was absolutely brilliant.”

Yan’s death shook the Chapel Hill community last August, bringing Carolina students and faculty together to mourn. A year later, Superfine and the APS department are still working through their grief for the loss of their beloved colleague. APS faculty honor him daily through their resilience — by pressing on with their science.

For Superfine, crafting wooden totems was a natural way to memorialize Yan. The wood will come from Carolina trees — creating an everlasting connection between Yan and UNC-Chapel Hill.

“A totem is an object that represents a family, an object of meaning that transcends the explicit object,” Superfine said. “And so maybe that’s what the benches will be. They’ll be representative of UNC as a family.”

‘A master of light and matter’

Zijie Yan and graduate student Anzhou Wen use an optical microscope to examine nanoparticles. (College of Arts and Sciences)

In his campus lab, Yan used laser beams to manipulate nanoparticles. He envisioned a future in which light waves could be employed in biomedicine, using holographic “optical tweezers” to control and construct nanostructures within cells.

It was the kind of work that almost sounds like science fiction.

“That’s what it sounds like, but with Zijie behind it, that science fiction would become reality,” said Theo Dingemans, the current APS department chair. “Zijie was really moving the boundaries of science at the nano level. He was at the forefront of nanotechnology.”

A September 2023 publication by the American Chemical Society called Yan “a master of light and matter, with nanometer precision,” highlighting four papers he published in ACS Nano.

Yan received a doctorate in materials engineering in 2011 from Rensselaer Polytechnic Institute, and he served as an assistant professor at Clarkson University before coming to Chapel Hill.

At Carolina, Yan’s research aimed to transcend the boundary between photonics and materials science. Yan built upon the work of scientist Arthur Ashkin, who won the Nobel Prize in physics in 2018 for his development of optical tweezers.

Former Carolina colleagues rave about Yan’s creativity in the lab as he worked with his team to develop new techniques for light-matter interactions. Yan used light waves to trap and precisely manipulate nanoparticles, opening the possibility of building nanostructures and material assemblies.

Yan’s creativity extended to both his experiments and his theoretical work. He was passionate about his science – and about finding potential applications for it.

“There are people who are really talented with experiments and people who are brilliant with theory,” Superfine said. “He could do both, and that’s pretty unusual. He was just a master in a very complex set of physics and materials questions. He was creative and just masterful.”

A mentor and a father

The door to Yan’s office in Caudill Labs remains locked. Maybe in time the office will be occupied again. But for now the pain is too fresh, the loss too great.

Assistant professor Nicolas Pégard works in an office across the hall from Yan’s. He sees that locked door every day, and he remembers how — not too long ago — it was always open.

Yan had an introverted personality. He was quiet and unassuming, but he always had time for his students. They would drop by his office throughout the day.

“He was not an outgoing social butterfly, but he did care about all his students very, very well,” Pégard said. “He treated them with respect. He was very much, by any standard, someone who met regularly, cared about helping his students and giving them opportunities the same way he cared about his own kids.”

Pégard and Yan collaborated on multiple projects together. But the conversations Pégard remembers most had nothing to do with science.

As fathers of young children, Yan and Pégard talked often about family life, the educational system and ways to set their children up for success. One time, the colleagues even bumped into each other at the same children’s event at the North Carolina Museum of Art in Raleigh.

Several times, Yan brought his oldest daughter to Caudill Labs to tag along during his workday. Unlike her father, she very much is a social butterfly, and she would often burst into Pégard’s office, calling him “Nico!” One time, she walked in and handed Pégard a picture she drew of her father and Pégard side by side.

“I remember giving that drawing to her dad a week later,” Pégard said, smiling. “I was like, ‘It’s so adorable. I can’t keep that from you. You should have it.’”

The Carolina community lost a brilliant scientific mind. The APS department lost a dear colleague and friend. Children lost their father.

Grief doesn’t just disappear. A year after Yan’s death, the community is still healing.

“This is a process of many years. We just went through Year 1,” Dingemans said. “Aug. 28 is going to have a special meaning for us forever.”