Qing “Shilo” Xia joins Purdue Physics and Astronomy faculty
2026-01-16
Qing “Shilo” Xia has spent her career chasing something no one has ever seen directly but that shapes the universe on the largest scales imaginable.
Dark matter, an invisible form of matter that makes up about 85% of all matter in the universe, does not emit or reflect light. Astronomers know it exists because of what it does to galaxies, bending their motions and holding them together. What dark matter is made of, however, remains one of the most profound open questions in modern physics.
Xia, an assistant professor of physics and astronomy at Purdue University, has joined the faculty, determined to help answer that question. Her research focuses on developing and using some of the most sensitive detectors ever built to search for rare signals of dark matter interacting with ordinary matter.
“We’ve known for a while that we are ignorant of what makes up the majority of our universe,” Xia said. “When astronomers look at galaxies, they see stars at the edges spinning much too fast, as if some invisible matter is holding them together, and this is just one of many pieces of evidence for the existence of dark matter.”
Xia is part of the international LUX-ZEPLIN, or LZ, collaboration, which operates the world’s most sensitive detector for one of the leading dark matter candidates. The experiment uses a detector filled with about 10 metric tons of liquid xenon, buried deep underground to shield it from cosmic radiation and other sources of interference. The goal is to observe the incredibly rare event of a dark matter particle colliding with a xenon atom.
“The dark matter we are searching for might only interact once in hundreds of light-years of solid lead,” Xia said. “It’s even harder than finding a needle in a haystack, since this needle usually passes through the hay without touching anything.”
To succeed, physicists must build large detectors, operate them for years, and carefully distinguish signals from background noise caused by cosmic radiation or tiny impurities in materials. Xia’s work covers detector design, calibration, and data analysis, aiming to push current technology. Now at Purdue, her research builds on a career shaped by international experiences and mentors emphasizing scientific rigor and integrity.
Xia grew up in Nanjing, a historic city in eastern China with a population of several million. As a student, she was drawn to math and soon discovered physics as a way to use mathematics to explain the real world.
After completing her undergraduate studies in China, Xia moved to the United States in 2014 to pursue a Ph.D. in physics at Yale University, where she focused on particle physics. She earned her doctorate in 2020 and then joined Lawrence Berkeley National Laboratory as a postdoctoral researcher, working there until the end of 2025. She arrived at Purdue less than a month ago and is already settling into the rhythm of a college town.
“I enjoy the lively college town of West Lafayette,” Xia said. “My hometown is a hustling and bustling city with a population of several million, so it’s very different from the much quieter town of West Lafayette. However, my hometown also has many colleges, and some areas are full of young people just like here.”
At Purdue, Xia is building a research group focused on dark matter direct detection and the development of new technologies to explore regions of dark matter parameter space that remain largely uncharted. While the LZ experiment targets dark matter, it is also sensitive to neutrinos, another class of elusive particles.
“We know much more about neutrinos than dark matter since they have been detected before by many other experiments,” Xia said. “But they are also elusive particles and some properties of them remain to be revealed.”
Her publication record reflects this blend of experimental innovation and fundamental physics. She is an author on “Dark Matter Search Results from 4.2 Tonne-Years of Exposure of the LUX-ZEPLIN (LZ) Experiment,” published in Physical Review Letters, as well as papers on the design and performance of LZ calibration systems and on future dark matter searches using crystalline xenon.
Alongside her research, Xia is deeply invested in teaching and mentoring students. She describes teaching as a feedback loop that renews her own sense of wonder.
“The most rewarding aspect of teaching is when a difficult concept suddenly clicks for a student, and that excitement reminds me of why I fell in love with physics when I was a student,” she said. “It’s a positive cycle. Their discovery helps me rediscover the parts of the field I’ve started to take for granted after years of specialized research.”
Physics can feel abstract, especially when it relies heavily on mathematics. Xia embraces that challenge rather than shying away from it.
“Physics is more relatable when it is connected to real-world examples, and I find teaching more engaging when it is complemented by lab demo or everyday phenomena,” she said. “But I also believe there’s more beauty in physics we can appreciate when we grasp the underlying math, even when it gets abstract, as that’s where the logic of the universe lives.”
She chose Purdue for its strength in both physics and engineering and for the opportunities it offers students to engage directly in cutting-edge research.
“Purdue is a prestigious university with very strong programs in physics and engineering,” Xia said. “I believe I will have access to great resources to further my academic pursuits. In the meantime, I can contribute to the university by providing opportunities for students to develop skills in particle physics research.”
Beyond the lab and classroom, Xia has a reflective side shaped by her appreciation for the history of science. If she could witness any discovery firsthand, she points to the revelation of asymptotic freedom in the 1970s, which transformed physicists’ understanding of the strong nuclear force.
“It is counterintuitive, as most forces, such as gravity and electromagnetic force, get stronger as the distance gets shorter,” she said. “However, the strong force was discovered to become weaker at shorter distances and higher at larger distances. This unexpected behavior reshaped our understanding of the laws of nature.”
She also finds a personal resonance in that idea. “I find it fascinating also because the principle seems to apply to interpersonal relationships,” Xia said. “The closer you are to someone, the more freedom you should allow them, yet at greater distances you can remain strongly connected.”
If she were not a physicist, Xia imagines a life still guided by curiosity and creativity. “If I had had the opportunity growing up, I would also have liked to pursue a career in music composition or wildlife filming,” she said. “More practically speaking, if I were not a physicist, I could imagine myself in other science-related professions that combine problem-solving with curiosity, and I am also interested in public policy.”
For now, her focus is firmly on the invisible matter that holds galaxies together and on training the next generation of physicists to ask bold questions about the universe. “With dedication and a bit of luck,” she says, “we may be able to see a signal in the coming years.”
About the Department of Physics and Astronomy at Purdue University
Purdue's Department of Physics and Astronomy has a rich and long history dating back to 1904. Our faculty and students are exploring nature at all length scales, from the subatomic to the macroscopic and everything in between. With an excellent and diverse community of faculty, postdocs and students who are pushing new scientific frontiers, we offer a dynamic learning environment, an inclusive research community and an engaging network of scholars.
Physics and Astronomy is one of the seven departments within the Purdue University College of Science. World-class research is performed in astrophysics, atomic and molecular optics, accelerator mass spectrometry, biophysics, condensed matter physics, quantum information science, and particle and nuclear physics. Our state-of-the-art facilities are in the Physics Building, but our researchers also engage in interdisciplinary work at Discovery Park District at Purdue, particularly the Birck Nanotechnology Center and the Bindley Bioscience Center. We also participate in global research including at the Large Hadron Collider at CERN, many national laboratories (such as Argonne National Laboratory, Brookhaven National Laboratory, Fermilab, Oak Ridge National Laboratory, the Stanford Linear Accelerator, etc.), the James Webb Space Telescope, and several observatories around the world.
Written by: David Siple, communications specialist, Purdue University Department of Physics and Astronomy