Bold claim: hyper-entangled photons can keep their coherence across a much wider range of colors in complex media, upending the long-held limits of imaging and communication through scattering materials.
In this work, Ronen Shekel, Ohad Lib, Sébastien M. Popoff, and Yaron Bromberg show that when photons are specially paired with both spatial and spectral entanglement (hyper-entangled), the chaotic dispersion that one photon experiences in complex environments is effectively neutralized by its entangled partner. The result is a two-photon bandwidth that far exceeds what conventional light can achieve. This not only deepens our understanding of light behavior in intricate media but also opens doors to high-bandwidth wavefront shaping and enhanced performance in challenging optical systems.
The researchers demonstrate dispersion cancellation analytically and numerically: the first-order chromatic modal dispersion affecting one photon is cancelled by its spectrally anti-correlated twin. This leads to stable spatial correlations across a broad bandwidth, surpassing classical limits. They illustrate the principle using multimode fibers, thin diffusers, and blazed gratings, and show how it can be applied to broadband wavefront shaping.
Broadband Entanglement and Diffraction Analysis
The team explores how spatially entangled photon pairs interact with diffractive elements to boost imaging performance. Their results indicate that, thanks to quantum properties, these photons effectively experience a single diffraction order, which improves spatial resolution and reduces noise. A theoretical framework modeling entangled photons interacting with a blazed grating supports broadband operation without the typical chromatic aberrations seen in standard imaging systems. The model accounts for finite beam size and the specific characteristics of the entangled photons, laying a solid ground for experimental verification.
Two-Photon Dispersion Cancellation in Complex Media
This work marks a substantial advance in understanding light propagation through complex materials. Classical correlations fade as bandwidth grows, but quantum correlations between entangled photons stay strong, yielding high-contrast speckle patterns. By exploiting these properties, the study bypasses the usual bandwidth constraints imposed by complex media. The authors note a simplifying assumption in their model: the diffusers are thinner than the Rayleigh range of the Gaussian beam, which neglects diffraction within the diffuser. Future research could test how well these findings hold when diffraction within the diffuser becomes non-negligible and explore extending the framework to more intricate scattering environments.
For further details
Two-Photon Bandwidth of Hyper-Entangled Photons in Complex Media
ArXiv: https://arxiv.org/abs/2512.09456
