Insider Brief
- Scientists at Penn have pioneered a revolutionary quantum sensing approach capable of detecting signals from single atoms, marking a significant breakthrough in molecular analysis precision.
- This innovative method focuses on individual nuclei to identify subtle molecular structure variations, paving the way for breakthroughs in pharmaceutical development and protein studies.
- The breakthrough leverages nitrogen-vacancy centers within diamonds, merging classical theoretical principles with cutting-edge technology to explore new horizons in quantum physics and spectroscopic analysis.
- Image: An artistic visualization depicting the subtle nuclear variations observable through the novel nuclear quadrupolar resonance technique outlined in the research paper. (Mathieu Ouellet)
PRESS RELEASE — For over seven decades, scientists have harnessed radio waves to identify molecular signatures of unknown substances, supporting diverse applications from medical imaging through MRI technology to security screening at airports.
However, these conventional approaches depend on averaged signals from billions upon billions of atoms, making it challenging to detect subtle molecular variations. These constraints create roadblocks in crucial research areas, particularly protein studies, where minimal structural differences can significantly impact functionality and potentially determine wellness outcomes.
Sub-Atomic Discoveries
Recently, researchers at the University of Pennsylvania School of Engineering and Applied Science (Penn Engineering) have successfully employed quantum sensors to develop an innovative version of nuclear quadrupolar resonance (NQR) spectroscopy, a method traditionally employed for detecting illicit substances and analyzing pharmaceutical compounds.
Published in Nano Letters, this groundbreaking technique achieves such exceptional precision that it can identify NQR signals from individual atoms — an achievement previously considered impossible. This remarkable sensitivity creates new possibilities for advancement in pharmaceutical research, where atomic-level understanding of molecular interactions is essential.
“Our method enables us to examine individual nuclei and detect minute variations in seemingly identical molecules,” explains Lee Bassett, Associate Professor in Electrical and Systems Engineering (ESE), Director of Penn’s Quantum Engineering Laboratory (QEL) and the study’s senior author. “By examining one nucleus at a time, we can uncover structural and dynamic molecular characteristics that were previously undetectable. This advancement allows us to examine nature’s fundamental components at an unprecedented level of detail.”
An Unexpected Discovery
The breakthrough emerged from an unexpected observation during standard experimental procedures. Alex Breitweiser, who recently completed his Physics doctorate at Penn’s School of Arts & Sciences and served as the paper’s co-first author, now conducting research at IBM, was investigating nitrogen-vacancy (NV) centers in diamonds — microscopic defects commonly utilized in quantum sensing — when he detected unusual data patterns.
The rhythmic signals initially appeared to be experimental artifacts, but they remained consistent despite thorough troubleshooting efforts. Drawing from nuclear magnetic resonance textbooks dating back to the 1950s and ’60s, Breitweiser identified a physical mechanism that provided an explanation for their observations, though this phenomenon had previously been considered experimentally negligible.
Modern technological capabilities enabled the research team to detect and quantify effects that were previously undetectable with scientific equipment. “What we initially thought was an anomaly,” Breitweiser explains, “turned out to be our entry into a new frontier of physics, accessible through our advanced technology.”
Unprecedented Precision
The team’s understanding of this effect was enhanced through collaboration with scientists at Delft University of Technology in the Netherlands, where Breitweiser had previously conducted related research during an international fellowship. By combining their collective expertise in experimental physics, quantum sensing, and theoretical modeling, the team developed a methodology capable of detecting individual atomic signals with remarkable accuracy.
“Think of it as identifying a single cell in an enormous spreadsheet,” says Mathieu Ouellet, a recent ESE doctoral graduate and paper co-first author. “While traditional NQR provides an averaged overview — offering general insights but lacking specific details — our method reveals the underlying individual data points, enabling us to isolate and analyze signals from single nuclei and understand their distinct characteristics.”
Deciphering the Signals
The process of understanding the theoretical foundations behind these unexpected experimental results required extensive investigation. Ouellet methodically evaluated various hypotheses, conducting numerous simulations and calculations to correlate the data with possible explanations. “The process resembles medical diagnosis,” he notes. “While the data indicates something unusual, multiple explanations often exist. Reaching the correct conclusion required considerable time and analysis.”
Looking toward the future, the research team envisions broad applications for their methodology in addressing critical scientific challenges. This novel approach, capable of characterizing previously undetectable phenomena, could significantly advance scientists’ understanding of the molecular mechanisms that govern our natural world.
The research was conducted at the University of Pennsylvania’s School of Engineering and Applied Science with funding from the National Science Foundation (ECCS-1842655, DMR-2019444). The project received additional backing through a Ph.D. Fellowship from the Natural Sciences and Engineering Research Council of Canada awarded to Ouellet, and an IBM Ph.D. Fellowship granted to Breitweiser.
The research team also included Tzu-Yung Huang, a former doctoral student in ESE at Penn Engineering who now works at Nokia Bell Labs, and Tim H. Taminiau from Delft University of Technology.
