A global team of scientists has demonstrated that concentrated sunlight can produce pairs of quantum-entangled photons. Their findings were published in the journal Optica.
The authors of the study include experts from the University of Ottawa and the Max Planck Institute for the Science of Light in Germany.
In their experiment, the researchers utilized sunlight as a pump source for spontaneous parametric down-conversion, a standard technique for creating pairs of entangled photons. This result challenges the notion that lasers are the only viable option for preparing quantum states of light.
Previously, lasers were deemed almost indispensable due to their high coherence and power density. However, the researchers demonstrated that the spatial and temporal incoherence of sunlight does not significantly hinder the generation of 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 square meters. They focused the light using a Fresnel lens, directed it into a glass conical concentrator, and then into a multimode fiber before feeding it into a nonlinear crystal.
The output yielded polarization-entangled photons with an accuracy of nearly 94%, exhibiting correlations that violate Bell's inequality. These results confirmed genuine quantum entanglement.
The researchers stated that the normalized efficiency of this method is comparable to that of laser systems. They believe this approach could reduce the energy costs of photonic quantum systems and simplify their use in energy-sensitive applications, such as satellites and interplanetary missions.
In July, specialists from Amazon Web Services (AWS), Nvidia, Lawrence Berkeley National Laboratory, and NASA assessed the need for supercomputers in quantum systems.