Tracking tumors with quantum optics

Various imaging techniques are used in the diagnosis of cancer. The aim is to detect tumour tissue and make it visible. When doctors discover suspicious tissue, they take a sample from it and examine it further: the gold standard of diagnostics are contrast methods that stain certain molecules and light microscopy to show their distribution.

Increasingly, digital microscopes are being used, which enable automated procedures and thus faster processes. Infrared-based imaging methods such as infrared microscopy join digital pathology and provide further information. Infrared light is used to excite molecules. Based on the vibrations of the molecules, it is now possible to deduce their type. Tissue is thus made visible without the need for additional contrast media. However, this method has limitations in detection because infrared detectors are limited in efficiency and signal-to-noise ratio.

“Spooky” quantum imaging

Quantum imaging can be used to circumvent this problem. The process uses a pair of photons that are “entangled” to define an image: The quantum state of one is linked to the other. The image is created by correlations between the two photons. Simplified, one light beam sends photons, i.e. light particles, to the tissue sample. The other light beam sends photons to a camera. Due to the quantum correlation of both photons, an image of the tissue sample is generated, although the light reaching the camera has never “seen” it – this is “spooky” quantum imaging.

Quantum imaging is now being combined with a professional microscopy system for the first time and will be tested in a clinical setting as part of the project.

“At TU Darmstadt, we take care of most of the experimental work of a fundamental nature,” explains Professor Markus Gräfe from the Institute for Applied Physics (IAP). “So we build the first laboratory experiments that show that everything works as desired and with which we investigate and optimise certain quantum imaging modes. Our setups are then transferred into compact forms by the Fraunhofer Institute for Applied Optics and Precision Engineering and combined with the microscope developed by our industrial partner Rapp OptoElectronic. The system will then be used at the Jena University Hospital. In perspective, this will introduce a new tool in cancer diagnostics.”