A Xiamen University team generated correlated photon pairs using sunlight alone and used them to reconstruct ghost images—the first reported sunlight-pumped SPDC ghost-imaging experiment.
The setup tracked the Sun, fed light through a 20-meter multimode fiber, and pumped a PPKTP nonlinear crystal indoors, overcoming sunlight’s shifting direction and intensity.
Image quality reached 90.7% visibility, close to 95.5% from a standard 405 nm laser at the same pump power, and the system also reproduced a more detailed two-dimensional “ghost face.”
Researchers said sunlight’s broad spectrum helped support quasi-phase matching, while longer data collection improved signal-to-noise and contrast-to-noise despite natural fluctuations.
The laser-free, power-free design could extend quantum imaging and information systems to remote sites or space, with better collection optics, crystal design and AI-assisted reconstruction seen as next steps.
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Quantum Ghost Imaging with Sunlight Reaches 90.7% Visibility, Paving the Way for Field-Deployable Quantum Systems
Overview
In May 2026, the Xiamen University team led by Wuhong Zhang and Lixiang Chen achieved a major breakthrough by demonstrating quantum ghost imaging powered entirely by natural sunlight. Detailed in the Advanced Photonics journal, this is the first time sunlight-excited spontaneous parametric down-conversion (SPDC) has been used for ghost imaging, marking a pivotal moment in the field. Traditionally, such experiments required powerful laboratory lasers, but this innovation bypasses artificial light sources, opening the door to more accessible and environmentally friendly quantum technologies. The team's work sets the stage for practical, sustainable quantum imaging beyond specialized labs.