Seeing Clearly in a New Field: Researchers Prototype a Next Generation of Quantum Microscopy

While quantum computing seems to be the most important element among developing technologies based on the behavior of matter and energy at the atomic and subatomic levels, another direction promises to open a new door for research. science itself: quantum microscopy.

With advances in quantum technologies, new modalities of microscopy are becoming possible, those that can see electric currents, detect fluctuating magnetic fields, and even see single molecules on a surface.

A prototype of such a microscope, demonstrating high resolution sensitivity, has been developed by an Australian research team led by Professor Igor Aharonovich of the University of Technology Sydney and Dr Jean-Philippe Tetienne of RMIT University. . The team’s findings have now been published in Natural Physics.

The quantum microscope is based on atomic impurities which, following laser illumination, emit light which can be directly linked to interesting physical quantities such as the magnetic field, the electric field or the chemical environment near the defect.

Professor Aharonovich said the ingenuity of the new approach was that, unlike the large crystals often used for quantum sensing, the research team used atomically thin layers, called hexagonal boron nitride (hBN).

“This van der Waals material, i.e. composed of strongly bonded two-dimensional layers, can be very thin and conform to arbitrarily rough surfaces, thus enabling high-resolution sensitivity,” said Professor Aharonovich. .

“These properties led us to the idea of ​​using ‘quantum-active’ hBN sheets to perform quantum microscopy, which is essentially an imaging technique that uses arrays of quantum sensors to create spatial maps of the quantities at which they are sensitive,” Dr. Tetienne said. said.

“Until now, quantum microscopy has been limited in its spatial resolution and application flexibility by the interface problems inherent in using a large three-dimensional sensor. Using a van der Waals sensor instead , we hope to expand the usefulness of quantum microscopy into arenas that were previously inaccessible.”

To test the capabilities of the prototype, the team performed quantum sensing on a technologically relevant magnetic material – a CrTe flake.₂a van der Waals ferromagnet with a critical temperature just above room temperature.

The hBN-based quantum microscope was able to image the magnetic domains of the ferromagnet, close to the sensor at the nanoscale and in ambient conditions, something previously thought impossible.

Additionally, using the unique properties of hBN defects, a simultaneous temperature map was recorded, confirming that the microscope can be used to perform correlative imaging between the two quantities.

Main authors for the Natural Physics paper, Ph.D. students Alex Healey (University of Melbourne) and Sam Scholten (University of Melbourne), and early career researcher Tieshan Yang (UTS), said the van der Waals nature of the sensor enabled the dual detection of magnetic properties and temperature.

“Because it’s very thin, little heat is able to dissipate through it, and any temperature distribution that exists is the same as if the sensor weren’t there,” they said. “What started as an experimental embarrassment ended up being a clue to a capability of our microscope that is unique among current alternatives.”

“There is enormous potential for this next generation of quantum microscopy,” said UTS principal investigator Dr. Mehran Kianinia. “Not only can it operate at room temperature and provide simultaneous temperature, electric and magnetic field information, but it can also be seamlessly integrated into nanoscale devices and withstand very harsh environments because hBN is a very stiff material.”

“Key future applications include high-resolution MRI (magnetic resonance imaging) and NMR (nuclear magnetic resonance) which can be used to study chemical reactions and identify molecular origins, as well as applications in space, defense and agriculture where remote sensing and imagery are key.”