Fraunhofer Converts IR Photons to Visible Through Quantum Entanglement

Fraunhofer IOF reports: "Bio-substances such as proteins, lipids and other biochemical components can be distinguished based on their characteristic molecular vibrations. These vibrations are stimulated by light in the mid-infrared to terahertz range and are very difficult to detect with conventional measurement techniques.

But how can information from these extreme wavelength ranges be made visible? The quantum mechanical effect of photon entanglement is helping the researchers allowing them to harness twin beams of light with different wavelengths. In an interferometric setup, a laser beam is sent through a nonlinear crystal in which it generates two entangled light beams. These two beams can have very different wavelengths depending on the crystal’s properties, but they are still connected to each other due to their entanglement.

“So now, while one photon beam in the invisible infrared range is sent to the object for illumination and interaction, its twin beam in the visible spectrum is captured by a camera. Since the entangled light particles carry the same information, an image is generated even though the light that reaches the camera never interacted with the actual object,” explains [Markus] Gräfe. The visible twin essentially provides insight into what is happening with the invisible twin."