Scientists found a way to generate quantum entanglement using sunlight, not lasers

Scientists have devised a method to create entangled photons using sunlight, rather than relying on lasers, according to a recent study. This discovery could potentially reduce the energy-intensive nature of quantum technology. Researchers from the University of Ottawa and the Max Planck Institute for the Science of Light conducted the experiment, publishing their findings in Optica.

Entangled photons, which are pairs of light particles with linked quantum properties, are crucial for various quantum computing and communication systems. Typically, lasers generate entangled photons through a process called spontaneous parametric down-conversion, due to the laser's coherent light properties. However, sunlight, while not coherent, was found to be capable of producing entangled photons if the quantum property did not depend on the light's wavelength or direction.

The team used a glass, cone-shaped concentrator to focus sunlight onto a thin optical fiber, which they tested outdoors over three days. The resulting photon pairs achieved a 94% fidelity with a perfectly entangled state, meeting the experimental requirements. While the entanglement quality was not as strong as that produced by laser systems, the researchers attribute the difference to distortions in the optical components.

The study's findings open up possibilities for more sustainable and potentially portable quantum technology applications, such as satellite-based quantum communications.