From Lab Tour to Quantum Leader: A Stony Brook Student’s Journey
As a high school senior touring Stony Brook University, Leonardo Castillo Veneros wasn’t expecting his future to crystallize in a physics lab. But a stop in Professor Eden Figueroa’s lab on that tour changed his future.
“Professor Figueroa gave an incredible tour,” said Castillo Veneros, now a first-year PhD student in physics at Stony Brook. “Even though I didn’t understand everything at the time, the equipment, the instruments — it was all so impressive. What really stood out was how passionate Professor Figueroa was. But it wasn’t just about his work, but bringing people in and getting others involved.”
That sense of welcome remained with Castillo Veneros. After enrolling at Stony Brook as an undergraduate in 2017, he reached out to Figueroa during his first year to inquire about opportunities to become involved with the lab. “He told me, ‘You don’t need to know everything to get started,’” said Castillo Veneros. “That made a big impact. Once you have a foot in the door, you can build your knowledge from there.”
Now a key member of Figueroa’s Quantum Information Technology Lab, Castillo Veneros is working on quantum networking and communication, helping develop cryptography systems and contributing to efforts to create a quantum network that spans from Stony Brook to Brookhaven National Laboratory (BNL) and beyond.
His focus is on building a cryptography system designed to function across 140 kilometers, laying the practical foundations for quantum repeaters, devices that could one day extend quantum networks over long distances. “It’s a really big project,” he said. “There’s still a lot of work to do, but it’s exciting.”
Castillo Veneros traced his initial interest in physics to a middle school science project, building a model of an atom. “Back then, the math looked like gibberish to me,” he said. “But the idea that we had tools to explain the invisible world, it stuck with me.”
Growing up in Clifton Park in upstate New York, he completed high school physics and looked for a university strong in science that could help him pursue his interest. That led him to Stony Brook’s Department of Physics and Astronomy, where he completed his undergraduate degree in 2021 and then earned a master’s degree through the Master of Science in Instrumentation program before entering the PhD program.
As a student researcher, he’s worked through the challenges of building complex systems with real-world applications. “With the quantum cryptography project, we were thrown into the water and had to learn how to swim,” he said. “There wasn’t a lot of existing infrastructure for what we’re trying to do. We’ve had to figure out a lot of the steps ourselves.”
The work, he said, is often unpredictable. “You come in, look at what went wrong yesterday, and try to fix it. If that uncovers more issues, you fix those too. It’s a constant process of problem-solving.”
One of the highlights of Castillo Veneros’ experience in the lab has been the mentorship style of Figueroa, whom he describes as a guiding but hands-off presence. “He gives us a lot of freedom as grad students,” he said. “You’re expected to explore, test your ideas, see what works and what doesn’t. It teaches you to be flexible and develop a systematic approach to research.”
That freedom has allowed Castillo Veneros to dive into several different projects, including quantum tomography — used to reconstruct quantum states and better understand experiments — and the heralding quantum memory and quantum gate projects, both critical for advancing quantum network infrastructure.
His animated explainer video of one of the lab’s systems that combines real footage, schematic diagrams and data was recently featured at Quantum 2.0/AspenNet Town Hall in San Francisco, where it earned enthusiastic feedback. “The idea was to bridge the gap between the simple concept of what we’re trying to do and the complex implementation we’ve developed,” he said. “It helps people see the connection between theory and application.”
Castillo Veneros is also a Bridge to the Doctorate Fellow, a program supported by the National Science Foundation’s Louis Stokes Alliances for Minority Participation. Managed by Stony Brook’s Center for Inclusive Education, the fellowship provides a stipend, tuition support, academic resources and professional development opportunities for graduate students from underrepresented backgrounds in STEM.
“I’ve found the Bridge to the Doctorate program to be incredibly supportive,” he said. “They check in regularly, offer workshops, and just make sure we’re doing okay. That sense of community is really important, especially in your first year of a PhD.”
Castillo Veneros’ work connects directly to BNL, where part of the lab’s experimental setup is located. He works with researchers there, reinforcing the collaboration between the two institutions that’s helping to establish Long Island as a hub for quantum research.
The long-term goal, he said, is to build a quantum repeater that would vastly extend the range of secure quantum communication.
“Everything we’re doing now is a stepping stone,” he explained. “The cryptography system mirrors the topology of the repeater we want to build. So getting that working is a major first step.”
Despite all that he’s accomplished, Castillo Veneros sees himself as still very much in the learning phase. “There’s still a lot of physics I need to learn. I have holes to fill. I want to become more fluent in the field,” he said. “That’s one of my goals before finishing my PhD.”
While his long-term career path remains open, he hopes to remain in research, possibly at a national lab or academic institution. “I really enjoy the work I’m doing now. I hope to find something similarly interesting to explore next.” His advice to undergraduates hoping to follow in his footsteps: “Don’t be afraid to reach out. Send the email, talk to a professor, ask to join a lab. There are so many opportunities, especially at Stony Brook, but you have to take the first step.”
— Beth Squire