A team of Brown University researchers will use a $2 million grant from the National Science Foundation to build a quantum mechanical magnetic camera, which will take snapshots of weak magnetic fields emanating from quantum materials. The camera will help researchers to understand the exotic materials that may one day be used in quantum computers and other quantum devices. 

“Just as the camera on your phone has an array of photosensors that register light and create an image, our device will use magnetic sensors that can ‘see’ magnetic fields and make images or movies of magnetic patterns,” said Gang Xiao, chair of the physics department at Brown and principal investigator on the new grant. “We can learn a lot about quantum materials by observing in great detail the magnetic fields they produce, and that’s what this device will let us do.”

Quantum technologies make use of the often-peculiar behavior of individual subatomic particles. Harnessing that behavior could create computers than can perform calculations far beyond the reach of even the fastest of today’s supercomputers, sensors far more powerful than those used currently and potentially unbreakable encryption modes. Making these quantum tools work depends on a deeper understanding of how particles in quantum systems interact. Magnetic fields offer a window into those interactions, and the magnetic camera could potentially reveal the intricacies of those fields.

The challenge is making the device sensitive enough to register the ultra-weak magnetic signals generated by many quantum materials. To do that, the researchers will have to improve magnetic tunnel junctions (MJTs), tiny quantum mechanical sensors currently used to read information from computer hard disks. Xiao, who has studied MTJs and related nanoscale magnetic phenomena for years, will lead the team in investigating new materials for assembling MJTs and work with electronics experts to build specialized circuitry around them. 

Joining Xiao on the team are three experts in quantum materials and phenomena: Vesna Mitrovic, Brad Marston and Kemp Plumb from Brown’s physics faculty. They’ll work with Professor of Engineering Alexander Zaslavsky and Senior Research Engineer William Patterson, both microelectronics experts. 

The grant also includes funding for student entrepreneurship training, with an eye toward marketing the technology once it’s completed. 

“The use for us is in exploring quantum materials, but if we’re able to scale this up, it could be useful for industry as well,” Xiao said. “A large enough camera could be useful in quality control for magnets used in a range of electronic devices. Similar devices could also be used in medical diagnostics to sense tiny shifts in magnetic fields generated by the heart or nervous system.”

Work on the project is scheduled to begin in January 2020. 

Original article: https://www.brown.edu/news/2019-11-06/qmmc