Quantum ghost imaging works using only sunlight in stunning new experiment Scientists turned sunlight into a quantum imaging tool, generating correlated photons without using a laser for the first time. - Date: - May 17, 2026 - Source: - SPIE--International Society for Optics and Photonics - Summary: - Scientists have achieved something that once sounded almost impossible: using ordinary sunlight to create quantum-linked photon pairs, a phenomenon normally dependent on precise laboratory lasers. By building a sun-tracking system that funnels sunlight through optical fiber into a special crystal, researchers generated strongly correlated photons capable of performing âghost imaging,â where images are reconstructed indirectly through quantum correlations. Remarkably, the sunlight-powered setup produced image quality close to that of a traditional laser system, even recreating detailed images like a âghost face.â - Share: Correlated and entangled photon pairs are essential tools in quantum optics. Scientists usually create these photon pairs through a process called spontaneous parametric down-conversion (SPDC), in which a powerful, highly stable laser shines into a nonlinear crystal. Because SPDC depends so heavily on coherent laser light, researchers have long considered the technique impractical outside carefully controlled laboratory environments. More recently, studies have shown that perfectly coherent light is not actually required for SPDC to work. Even partially coherent light sources can produce correlated photon pairs, while also transferring some of their own coherence properties to the generated photons. That discovery led researchers to ask an intriguing question: could sunlight itself be used to generate correlated photon pairs? Using Sunlight for Quantum Optics Turning sunlight into a usable SPDC source comes with major obstacles. Sunlight reaching Earth constantly fluctuates in brightness, direction, and position, making it difficult to maintain the precise alignment needed for SPDC experiments and photon detection. At the same time, sunlight offers a major advantage. Unlike lasers,