New quantum microscopy trick quadruples microscope resolution

Three years after a team of Caltech scientists showed that pairs of entangled photons could double the resolution of a light microscope, the same lab has figured out a way to double down on that improvement. They have now achieved a fourfold resolution boost compared to a classical microscope, using a new optical design that sends one of the entangled photons through the microscope's optics three times rather than just once.