Single Quantum Bit Sensing

Single-Qubit Sensing Puts New Spin on Quantum Materials Discovery

The Department of Energy’s Oak Ridge National Laboratory (ORNL) led the team of scientists involved in the single-qubit sensing quantum materials discovery. One of the key researchers mentioned is Ben Lawrie, a research scientist in ORNL’s Materials Science and Technology Division.

Ben Lawrie and his team used a specialized instrument called a scanning nitrogen-vacancy centre microscope to measure spin fluctuations near a phase transition in a magnetic thin film. This instrument allows scientists to detect signals on a single spin level to examine nanoscale structures.

The nitrogen-vacancy centre functions as both a quantum bit (qubit) and a highly sensitive sensor. The team moved this sensor around on top of the thin film to measure temperature-dependent changes in magnetic properties and spin fluctuations that cannot be measured any other way2.

The team’s work has revealed how local changes in spin fluctuations are linked together globally near phase transitions, which could lead to new spin-based information-processing technologies and deeper insights into wide classes of quantum materials.

Read More

Nanoscale Magnetic Ordering Dynamics in a High Curie Temperature Ferromagnet | Nano Letters

Scientists led by the Department of Energy’s Oak Ridge National Laboratory have developed a groundbreaking method to measure high-speed fluctuations in magnetic materials at nanoscale dimensions. This advancement could have significant implications for both traditional and quantum computing technologies.

Materials often undergo phase transitions characterized by temperature-dependent changes in fundamental properties. Understanding the behavior of materials near these critical transition temperatures is essential for developing new technologies. In this study, the team used a nanoscale quantum sensor to measure spin fluctuations near a phase transition in a magnetic thin film, which are crucial for data storage, sensors, and electronic devices.

The researchers utilized a scanning nitrogen-vacancy center microscope, which detects magnetic fields at the atomic scale, allowing them to examine nanoscale structures in detail. This instrument functions as both a quantum bit (qubit) and a highly sensitive sensor, enabling precise measurement of temperature-dependent changes in magnetic properties and spin fluctuations.

The team observed spin fluctuations as the thin film underwent phase transitions between different magnetic states induced by temperature changes. These measurements revealed how local spin fluctuations are interconnected globally near phase transitions, providing insights that could lead to new spin-based information-processing technologies and a deeper understanding of quantum materials.

Advances in spintronics and spin-based quantum computing hold the potential to improve digital storage and computing efficiency while enabling simulations previously inaccessible to classical systems. This research bridges ORNL’s capabilities in quantum information and condensed matter physics, contributing to the design of new quantum devices with applications in networking, sensing, and computing.

Reference: Yueh-Chun Wu, Gábor B. Halász, Joshua T. Damron, Zheng Gai, Huan Zhao, Yuxin Sun, Karin A. Dahmen, Changhee Sohn, Erica W. Carlson, Chengyun Hua, Shan Lin, Jeongkeun Song, Ho Nyung Lee, Benjamin J. Lawrie. “Nanoscale Magnetic Ordering Dynamics in a High Curie Temperature Ferromagnet.” Nano Letters. Link to article.

Personalities of Concern

Dr. Yueh-Chun Wu is a postdoctoral research associate in the Materials Science and Technology Division at Oak Ridge National Laboratory (ORNL). He earned his PhD in Physics from the University of Massachusetts Amherst in 2023 and joined the Quantum Heterostructure Group.

Dr. Wu’s research focuses on the development of quantum squeezed light and spin defects as quantum sensors for probing quantum materials. Before joining ORNL, his research was centered on optical spectroscopy of two-dimensional materials, investigating excitons, phonons, and electrons and their interactions in low-dimensional systems.

Dr. Gábor B. Halász is a theoretical physicist and R&D staff member at Oak Ridge National Laboratory (ORNL). He received his BA/MSc from the University of Cambridge in 2011 and his PhD from the University of Oxford in 2015. After a postdoctoral fellowship at the Kavli Institute for Theoretical Physics, he joined ORNL’s Materials Science and Technology Division in October 2018.

Dr. Halász’s research focuses on using quantum field theory and lattice model calculations to understand topological quantum materials, such as quantum spin liquids and topological superconductors. He is particularly interested in identifying definitive experimental signatures and exploring connections to quantum information science.

Dr. Joshua T. Damron is a Research and Development Staff Member at Oak Ridge National Laboratory (ORNL). He specializes in solid-state nuclear magnetic resonance (NMR) and quantum sensing materials. Dr. Damron has contributed to various research projects, including the development of diamond magnetometers and two-dimensional NMR spectroscopy with microfluidic diamond quantum sensors

Dr. Zheng Gai is a senior staff scientist at the Center for Nanophase Materials Sciences (CNMS) at Oak Ridge National Laboratory (ORNL). She joined ORNL in 2005 after working as a professor, associate professor, and postdoctoral fellow at Peking University, where she received her doctorate in surface science and her bachelor’s degree in condensed matter physics.

Dr. Gai’s research focuses on understanding the fundamental novel properties of quantum materials in the discipline of condensed matter physics. This includes the growth form and mechanisms, novel magnetic properties, superconductivity, and electronic properties. Some of her recent publications include studies on nanoscale magnetic ordering dynamics, cobalt-based pyroxenes, and room-temperature ferromagnetism in epitaxial bilayer FeSb/SrTiO3.

Dr. Huan Zhao is a Wigner Distinguished Staff Fellow at Oak Ridge National Laboratory (ORNL). His research interests include spin-based quantum sensing, solid-state quantum light sources, optical imaging, and microelectronics. Dr. Zhao has made significant contributions to the field of quantum materials and has published numerous papers on topics such as anisotropic excitons in monolayer black phosphorus and atomically thin femtojoule memristive devices

Yuxin Sun: Yuxin Sun is a PhD student in the Department of Computer Sciences at the University of Wisconsin-Madison. His research focuses on the theory of machine learning and algorithms, with recent work on algorithmic high-dimensional robust statistics and information-computation tradeoffs for statistical estimation.

Karin A. Dahmen: Karin A. Dahmen is a Professor of Physics at the University of Illinois at Urbana-Champaign. Her research interests include condensed matter physics, nonequilibrium dynamical systems, hysteresis, avalanches, earthquakes, population biology, and disorder-induced critical behavior.

Changhee Sohn: Changhee Sohn is an Assistant Professor in the Department of Physics at the Ulsan National Institute of Science and Technology (UNIST). His research focuses on condensed matter physics, including exotic magnetism, two-dimensional magnetism, and metal-insulator transitions driven by spin-orbit coupling.

Erica W. Carlson: Erica W. Carlson is a Professor of Physics and Astronomy at Purdue University. She specializes in superconductors, liquid crystals, and strongly correlated materials. She is also known for her work in physics education and the introduction of innovative technologies into her teaching.

Chengyun Hua: Chengyun Hua is a research scientist at Oak Ridge National Laboratory (ORNL). His research interests include mesoscale transport, ultrafast optical spectroscopy, and the development of quantum sensors.

Shan Lin: Shan Lin is an Assistant Professor in the School of Electrical, Computer, and Energy Engineering at Arizona State University. Her research focuses on AI and robotics, surgical robotics, and medical devices, with the goal of intelligent healthcare and autonomous surgery.

Jeongkeun Song: Jeongkeun Song is a postdoctoral researcher at Oak Ridge National Laboratory (ORNL). His research interests include atomic-scale control of oxide interfaces, emergent quantum phenomena in strongly correlated systems, and magnetotransport in antiferromagnetic oxide thin films.

Ho Nyung Lee: Ho Nyung Lee is a Corporate Fellow at Oak Ridge National Laboratory (ORNL). His research focuses on the precision design and discovery of novel interfacial properties and phenomena in epitaxial thin films and heterostructures, as well as the correlation and spin-orbit coupling in quantum materials.

Benjamin J. Lawrie: Benjamin J. Lawrie is a Senior Research Scientist at Oak Ridge National Laboratory (ORNL). His research centers on the development of quantum optical sensors, quantum nanophotonic systems, and the characterization of quantum devices at cryogenic temperatures.