An international team of scientists has demonstrated that concentrated sunlight can generate pairs of quantum-entangled photons. The study was published in the journal Optica.
The authors of the paper include experts from the University of Ottawa and the Max Planck Institute for the Science of Light in Germany.
In their experiment, researchers used sunlight as a pump source for spontaneous parametric down-conversion, a standard method for producing pairs of entangled photons. This challenges the notion that lasers are indispensable for preparing quantum states of light.
Previously, lasers were considered nearly irreplaceable due to their high coherence and power density. However, the researchers showed that the spatial and temporal incoherence of sunlight does not pose a critical limitation for generating polarization entanglement, provided the light remains polarized and is sufficiently focused.
For the experiment, the team assembled a solar light concentration system with a collection area of 1.4 m². The light was focused using a Fresnel lens, directed into a glass cone concentrator and multimode fiber, and then fed into a nonlinear crystal.
The output yielded polarization-entangled photons with an accuracy of nearly 94% and correlations that violated Bell’s inequality, confirming genuine quantum entanglement.
The researchers stated that the normalized generation efficiency is comparable to laser setups. They estimate that this approach could reduce the energy consumption of photonic quantum systems and simplify their use in energy-critical applications, such as satellites and interplanetary missions.
In July, experts from Amazon Web Services (AWS), Nvidia, Lawrence Berkeley National Laboratory, and NASA assessed the need for supercomputers in quantum systems.
