Optical microscopy is an essential tool in modern society. Light microscopes can detect objects through several physical processes, such as scattering, absorption, and reflection. However, in highly transparent samples these mechanisms are often too weak to acquire high contrast images.

Differential interference contrast (DIC) microscopy is a technique that can be used to detect tiny optical path differences (phase shifts) in transparent materials. Today, it is still one of the most reliable techniques that allow detection of transparent samples such as cells and protein layers.

The Q-MIC project aims to beat important limitations imposed by classical microscopy methods – it will implement quantum imaging technologies to create an enhanced microscope that will use single photons to image the samples, allowing non-invasive detection of cells, microorganisms, viruses or proteins. The Q-MIC microscope will perform low-light imaging of samples in the quantum regime, using significantly fewer photons than state-of-the-art systems.

For this purpose, Q-MIC partners aim to build a demo of a practical quantum device for imaging and metrology with integrated quantum light, an unconventional lens-free microscope, and high performance single-photon image sensors to reach unprecedented phase sensitivities over large field-of-view in the low light regime. This device will be built with consumer components, which would extend the impact well beyond the scientific interests and lead to portable, high throughput, non-invasive, and label free sensing of transparent objects, such as cells, micro-organisms, viruses and proteins.

Now, Q-MIC partners aim to publish a generalized quantum phase shifting digital holography (Q-PSDH) that works for multiphoton light beams. Together with other achievements within Q-MIC, the theoretical formulation of this experiment will be used for testing the quantum-enhanced differential-interference-contrast (DIC) microscope.

The fully integrated microscope will have applications such as biomedical analysis, allowing the detection of morphological and optical aspects in highly transparent living tissues at macroscopic level -such as lesions and cancer- with no labelling required and no damage risks due to low illumination levels. Other applications include the detection of properties and defects of materials with different refractive index, for example displays, solar cells or detectors.