Researchers have successfully demonstrated the transport of quantum light through a specialized optical fiber using Anderson localization, marking a significant advancement in quantum communications technology.
Originally invented in 1970, conventional optical fibers transmit data through a single core channel, but they’re approaching capacity limits due to exponential data growth. This has spurred research into alternative fiber structures and transmission approaches.
Anderson localization, named after physicist Philip W. Anderson who received the 1977 Nobel Prize, describes how particles (initially electrons) can become confined in disordered systems. This principle was later applied to light, with experiments demonstrating two-dimensional confinement while allowing propagation through the third dimension.
The breakthrough, published in Communications Physics, comes from researchers at ICFO in collaboration with Corning, Micro Photon Devices, and Politecnico di Milano. They successfully transported two-photon quantum states through a phase-separated Anderson localization optical fiber (PSF).
Unlike conventional fibers, PSFs contain multiple glass strands embedded in a glass matrix with two different refractive indexes. During fabrication, heating and drawing the borosilicate glass creates elongated strands with varying refractive indexes, generating lateral disorder that leads to Anderson localization of light.
Corning created a PSF capable of propagating multiple optical beams simultaneously with minimal spacing between them. The ICFO team then built an experimental setup using:
- A quantum light source generating correlated photon pairs at 810nm wavelength via spontaneous parametric down-conversion
- A single-photon avalanche diode (SPAD) array camera with exceptional sensitivity and time resolution
The researchers verified that the spatial anti-correlation of photon pairs was maintained after transmission through the PSF. They also conducted scaling analysis to identify optimal strand size distribution for 810nm wavelength light and suggested fabrication improvements to minimize attenuation and resolution loss.
This technology shows significant potential for applications in quantum imaging and communications, particularly for high-resolution endoscopy, entanglement distribution, and quantum key distribution.
Reference: Alexander Demuth, Robin Camphausen, Álvaro Cuevas, Nick F. Borrelli, Thomas P. Seward, Lisa Lamberson, Karl W. Koch, Alessandro Ruggeri, Francesca Madonini, Federica Villa, Valerio Pruneri. Quantum light transport in phase-separated Anderson localization fiber. Communications Physics, 2022; 5 (1) DOI: 10.1038/s42005-022-01036-5
