Femtoseconds and Attoseconds: The Key to Controlling Electron-Matter Interactions

A graduate student in Purdue University's Department of Physics and Astronomy is making waves in the world of Atomic, Molecular, and Optical (AMO) physics. With a passion for understanding the intricate dance between light and matter, Francis Walz has found a home in the Ultrafast Quantum Dynamics Laboratory, where he explores electronic dynamics using cutting-edge laser technology.

(Photo courtesy/Francis Walz)

Walz describes that, "In Atomic, Molecular, and Optical (AMO) physics research we study the fundamental interaction between light and matter." He explains that AMO physics encompasses a wide range of topics, including "quantum optics, precision measurements of fundamental constants, atomic clocks, and laser cooling of atoms." His specific work, however, zeroes in on "researching ultrafast electronic dynamics in atoms and molecules using femtosecond and attosecond laser pulses." Why does this matter? "If you can observe these dynamics, you can then control their behavior to drive novel electron-matter interactions," Walz says. This will ultimately be a prospect that could unlock new frontiers in science and technology.

Originally from Baltimore, Maryland, Walz earned his undergraduate degree in Applied Physics from Towson University in 2019, graduating Magna Cum Laude. He explains how his interest in physics began, saying, "I took my first physics class as a junior and thoroughly enjoyed learning this subject and solving the problems in class." By his senior year, advanced physics solidified his path. "I decided I wanted to study the subject in college." Research experiences during his undergraduate years further fueled his ambition, leading him to pursue a PhD. "I was lucky enough to have good research experiences that helped hone my interests and decided to pursue a PhD after I saw what opportunities a PhD could open for me," he says.

Purdue's reputation as a "cutting-edge research institution" with a "wide variety of interesting research" drew Walz to West Lafayette. "I came in undecided on what I wanted to study and having this variety was a top priority for me," he notes. Since arriving, he's immersed himself in the Ultrafast Quantum Dynamics Laboratory under the guidance of Professor Niranjan Shivaram.

His research has already gained recognition, earning an Editor's Pick award for his first published paper, Electric field measurement of femtosecond time-resolved four-wave mixing signals in molecules (Optics Express, 2022). As one of Shivaram's first graduate students, Walz has been pivotal in establishing the lab. His work in the Ultrafast Quantum Dynamics Laboratory has given him hands-on experience designing and constructing laser beampaths for experiments, something that has not only helped him hone his technical skills but also develop a deeper understanding of optics and laser physics.

Sidd Pandey and Francis Walz, Photo by Brian Powell.

Graduate students play a vital role in shaping the research landscape at Purdue, often taking on foundational work that drives innovation forward. Dr. Niranjan Shivaram, an assistant professor in the Department of Physics and Astronomy, reflects on the impact of Walz, one of his first graduate students, and his contributions to the ultrafast laser lab. “Walz is the first graduate student who joined my group when I started as an assistant professor here at Purdue. Being the first graduate student of my PhD adviser myself, I know how special this academic relationship can be,” says Shivaram. “Frank, along with my other graduate student at the time, Sidd Pandey, who graduated last year, built most of my ultrafast laser lab. I have been very fortunate to have an excellent graduate student like Frank in my research group.”

“Frank has an excellent work ethic. He is very consistent with his lab work and has a "just get it done" approach that I admire. He has exceptional skills with hands-on work particularly with laser related tasks,” says Niranjan. “Walz takes pride in his work. As they say, excellence is an attitude and Walz personifies that. I think the desire to do well in any task he promises to complete is what motivates him in addition to his interest in physics.”

Outside the lab, Walz appreciates the strong sense of community he has built at Purdue. "I have enjoyed working with all my fellow graduate students in the lab. We try to have some fun in and outside the lab as much as we can," he says. "We go on picnics and get coffee during the day and try to build a solid group culture." On a personal note, he finds a unique joy in sharing the department with his wife. Walz says, "I find my wife working in the same department as me very enjoyable. We are very fortunate that we can work at the same location."

Adjusting to West Lafayette from Baltimore hasn't been a drastic shift for Walz. "Living in Lafayette isn't too different than Baltimore. There are less people, but everything that I enjoy doing is still around," he says. He enjoys playing tennis and pickleball with his wife, as well as golfing, and appreciates the lower cost of living. "I can afford to do more things around town," says Walz. The college town vibe, with its coffee shops and bookstores within walking distance, adds a charm distinct from his suburban Baltimore upbringing.

Photo by Brian Powell.

His family has been incredibly supportive of his academic journey. "My family has always been very supportive of me studying physics. Both my father and mother have given me so many good pieces of advice, especially as I have moved on closer towards graduation. My other eight siblings also helped me stay connected to my family and offered support when needed." Having a large support system has played an important role in his journey, helping him maintain a balance between his academic and personal life.

Walz has made a lasting impact through his work, demonstrating technical expertise and leadership. Shivaram shares high praise for Walz’s skills and the qualities that set him apart as a researcher and collaborator. “Walz is an excellent experimental physicist with particular strength in ultrafast laser research,” says Shivaram. “He has very strong experimental skills and a great temperament for research. He is a very good team player and, at the same time, has what it takes to lead a team. In my opinion, he will be highly successful in his future endeavors, and any team he joins in the future will be fortunate to have him.”

Looking ahead, Walz is keeping his options open post-graduation. "I hope to find a job in an industry setting. I would be interested in optical engineering or laser design," he says. "I am also interested in researching optical systems as an optical physicist." While he's applied to a variety of positions, including post-doctoral opportunities, he's ready to see "where life takes me."

His journey through Purdue has been one of exploration, discovery, and growth. "I enjoy all the people I've met here; I think I have been very fortunate to meet some wonderful people personally and professionally who helped me grow and develop into the man I am today," Walz says, reflecting on his time at Purdue University. As he prepares to take the next step into the professional world, his passion for physics, research, and innovation remains steadfast. Whether in academia or industry, it's clear that Walz will continue to push the boundaries of physics and light-matter interactions for years to come.