Ultra-thin quantum sensors survive 30,000 times the pressure of air

Physicists at Washington University in St. Louis have developed ultra-thin quantum sensors made from crystallized boron nitride that can measure stress and magnetism under pressures exceeding 30,000 times atmospheric pressure. These sensors leverage vacancies created by neutron radiation beams that knock boron atoms out of the boron nitride sheets, trapping electrons whose quantum spin states change in response to local magnetic fields, stress, or temperature. Unlike previous diamond-based quantum sensors, these two-dimensional boron nitride sensors are less than 100 nanometers thick, allowing them to be placed extremely close—within a nanometer—to the material under study, enhancing measurement precision under extreme conditions. To apply such high pressures, the team uses diamond anvils—tiny, durable flat surfaces about 400 micrometers wide—that compress the sample material. Initial tests demonstrated the sensors’ ability to detect subtle magnetic changes in two-dimensional magnets. Future plans include studying materials from high-pressure environments like Earth’s core to better understand geological phenomena