Wavefront correction with photon echoes

V. Jacques, E Wu, Timothée Toury +4 more

Yanis Trouyet, Neelan Gounden, Pedro Ornelas +3 more

Wavefront shaping is a key technique for mitigating scattering in complex media, enabling advanced imaging and optical communication. Yet existing approaches are inherently local, requiring active correction elements - such as spatial light modulators or deformable mirrors - to lie directly in the optical path of the scattered light, which limits their integration into compact imaging systems. Here, we experimentally demonstrate nonlocal wavefront shaping using spatially entangled photon pairs. By applying a phase correction to a photon that never interacts with the scattering medium, we compensate for the distortions experienced by its entangled partner and restore their initial spatial correlations. Our approach physically decouples the wavefront correction from the scattering medium, paving the way for imaging through complex media in compact and otherwise inaccessible systems.

Sven R. Hartmann

Kiran Bajar, Rounak Chatterjee, Vikas S. Bhat +1 more

Wavefront manipulation and correction using feedback-based optimization have long been employed in optical applications such as microscopy, optical sensing, astronomical imaging, and communication. With recent advances in quantum optics, wavefront correction has become a crucial tool in quantum imaging, quantum communication, and efficient photon coupling. Consequently, understanding the performance of optimization algorithms under low-photon conditions is essential for the effective deployment of quantum optical systems. This study investigates the performance of two algorithms in the photon-counting regime across varying mean photon rates through experiments and numerical simulations. Furthermore, we propose, simulate, and implement a novel, to the best of our knowledge, augmented algorithm that combines the strengths of both methods and is particularly well suited for quantum applications.

Raymond John Beach, Burton Brody, Sven R. Hartmann

Kiran Bajar, Ronen Shekel, Vikas S. Bhat +3 more

Spatial entanglement is a key resource in quantum technologies, enabling applications in quantum communication, imaging, and computation. However, propagation through complex media distorts spatial correlation, posing a challenge for practical implementations. We introduce a symmetrized genetic algorithm (sGA) for adaptive wavefront correction of spatially entangled photons, leveraging the insight that only the even-parity component of wavefront distortions affects two-photon correlation. By enforcing symmetry constraints, sGA reduces the optimization parameter space by half, leading to faster convergence and improved enhancement within a finite number of generations compared to standard genetic algorithms. In addition, we establish the dependence of enhancement on the signal-to-noise ratio of the feedback signal, which is controlled by detector integration time. This technique enables correction of entanglement degradation, enhancing quantum imaging, secure quantum communication, and quantum sensing in complex environments.