Quantum mechanics

Uncertainty principle

Scanning probe microscopy

Materials science

Microscopy

Computer science

Quantum imaging

Resolution (logic)

Image resolution

Photon

Quantum sensor

Physics

Optics

Optical microscope

Quantum technology

Artificial intelligence

Quantum

Scanning electron microscope

Diffraction

Quantum dot

Near-field scanning optical microscope

Optoelectronics

Open quantum system

Nature Photonics

The principles of quantum optics have yielded a plethora of ideas to surpass the classical limitations of sensitivity and resolution in optical microscopy. While some ideas have been applied in proof-of-principle experiments, imaging a biological sample has remained challenging, mainly due to the inherently weak signal measured and the fragility of quantum states of light. In principle, however, these quantum protocols can add new information without sacrificing the classical information and can therefore enhance the capabilities of existing super-resolution techniques. Image scanning microscopy, a recent addition to the family of super-resolution methods, generates a robust resolution enhancement without reducing the signal level. Here, we introduce quantum image scanning microscopy: combining image scanning microscopy with the measurement of quantum photon correlation allows increasing the resolution of image scanning microscopy up to twofold, four times beyond the diffraction limit. We introduce the Q-ISM principle and obtain super-resolved optical images of a biological sample stained with fluorescent quantum dots using photon antibunching, a quantum effect, as a resolution-enhancing contrast mechanism. Characterizing not only the fluorescence intensity but also the inherent quantum correlations of the fluorescent photon stream can enhance the spatial resolution of image scanning microscopy up to twofold, a fourfold improvement over the diffraction limit.

Super-resolution enhancement by quantum image scanning microscopy