Particle.news
Get it on Google Play
Download on the App Store
5 ARTICLES
·
23h ago

Researchers Generate Quantum Entanglement From Sunlight

Outdoor experiments show concentrated natural sunlight can drive a standard nonlinear process to produce high-fidelity polarization-entangled photon pairs.

Using a new cone-shaped solar concentrator, researchers showed that sunlight can be used to create entangled photons. This could one day enable satellites to create secure encryption keys using the sunlight already abundant in space. (Credit: Florian Sterl)
Cheng Li is shown with the outdoor experimental setup. The sunlight concentration module, including the Fresnel lens and the solar concentrator, is mounted on a solar-tracking motor to ensure stable power delivery. The entanglement generation and detection setup, including the nonlinear crystal and the single-photon detectors, are shielded in an optical enclosure placed inside a blackout tent.
Image

Overview

  • A team from the University of Ottawa and the Max Planck Institute reported in Optica that outdoor tests produced entangled photon pairs using concentrated sunlight in a proof-of-principle experiment performed Thursday.
  • The setup used a window-sized Fresnel lens and a cone-shaped all-glass solar concentrator to funnel sunlight into a hair‑width optical fiber that pumped a millimeter-scale nonlinear crystal via spontaneous parametric down-conversion.
  • Quantum state tomography measured about 94 percent fidelity to an ideal polarization-entangled state and the photon correlations violated Bell’s inequality, confirming genuine quantum entanglement.
  • The sunlight-driven source currently lags top laser-based systems in photon brightness and some quality metrics, so the teams are working on optical and engineering improvements to boost output and make field or satellite deployment feasible.
  • The result builds on prior theory and LED experiments that showed incoherent light can yield polarization entanglement and points to a future where ambient solar radiation could cut the power, weight, and cost of some quantum communication hardware.