Photon entanglement enhances microscope resolution.

Researchers at Caltech have developed a new microscopy technique called quantum microscopy by coincidence (QMC) that uses quantum entanglement of photons to double the resolution of light microscopes. By using entangled photons, the microscope can see even smaller things, resulting in increased resolution. QMC gets around the limit of using shorter-wavelength light, which can damage living cells, by using biphotons that carry the lower energy of longer-wavelength photons while having the shorter wavelength of higher-energy photons. The paired photons remain entangled as a biphoton behaving at half the wavelength despite the presence of the object and their separate pathways.