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Researchers at The City College of New York have shown how a quantum emitter, the nitrogen-vacancy (NV) center in diamond, interacts in unexpected ways with a specially engineered photonic structure when moved around with a scanning tip.

The study, led by Carlos A. Meriles—Martin and Michele Cohen Professor of Â鶹ÒùÔºics in the Division of Science—and titled "Emission of Nitrogen–Vacancy Centres in Diamond Shaped by Topological Photonic Waveguide Modes," in the journal Nature Nanotechnology.

What has long been considered a drawback of the NV center—its broad and messy emission spectrum—turns out to enable a new type of coupling that reshapes its light in ways not seen before. This discovery has fundamental importance for quantum information technologies, since such coupling could help overcome longstanding challenges like spectral diffusion and open pathways toward robust spin–photon and spin–spin entanglement on a chip.

At the same time, the work demonstrates a novel sensing capability: by analyzing the NV emission, the team could reconstruct detailed, polarization-resolved images of the photonic modes with remarkable contrast.

"Beyond photonic structures, this polarization sensitivity could eventually be applied to detecting chiral molecules, which are central to biology and medicine," said Meriles.

He added that follow-up research will continue in both directions—probing quantum emitter–structure interactions more deeply and developing new sensing applications based on the same principles.