Signal Researchers generate quantum entanglement directly from sunlight

Summary

A team from the University of Ottawa and the Max Planck Institute for the Science of Light generated quantum entanglement using sunlight in place of a laser, with results published in the journal Optica. The researchers used a cone-shaped solar concentrator and spontaneous parametric down-conversion (SPDC), in which a pump beam entering a nonlinear crystal splits individual photons into entangled pairs. In an outdoor experiment, the entangled photons produced showed about 94% similarity to an ideal quantum state. The finding challenges the long-standing assumption that lasers are indispensable for preparing quantum states of light. The team said the approach could pave the way for simpler, lower-power quantum satellites, secure communications and more energy-efficient quantum computing.