Lightless Image

Researchers from the Institute for Quantum Optics and Quantum Information (IQOQI), the Vienna Center for Quantum Science and Technology and The University of Vienna have developed a fundamentally new quantum imaging technique that has striking counterintuitive features. The imaging technique obtained an image without detecting the light that was used to illuminate the imaged object, while the light revealing the object never touched it.

Generally to obtain an image of an object, one must illuminate it with a beam of light and then use a camera to sense the light that is either scattered or transmitted through the object. The type of light used to shine the object depends on the properties that one would like to photograph. Unfortunately, cameras with ideal lights do not exist.

The experiment published in the journal Nature exposed this seemingly self-evident limitation. The object (in this case the contour of a cat) is illuminated with light that remains undetected. Moreover, the light that forms an image of the cat on the camera never interacts with it. During the experiment, scientists used so-called ‘entangled’ pairs of photons. These pairs of photons, which are like interlinked twins, are created when a laser interacts with a non-linear crystal. In the experiment, the laser illuminates two separate crystals, creating one pair of twin photons in either crystal. The object is placed in between the two crystals. The arrangement is such that if a photon pair is created in the first crystal, only the infrared photon passes through the imaged object. Its path then goes through the second crystal where it fully combines with any infrared photons that would be created there.

Researchers are confident that their new imaging concept is versatile which could even enable imaging in important mid-infrared region. It could find applications where low light imaging is crucial, in fields such as biological or medical imaging.