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Throughout the initial three years of his fellowship, Dr. Moreau and his team concentrated on establishing a research environment for quantum imaging at NCKU. The laboratory is fully operational, serving as a platform for ongoing experiments that leverage high-dimensional entanglement to explore imaging capabilities beyond classical limits.

Recently the team has worked with collaborators from the National Research Council of Canada and the University of Ottawa to release new results [arXiv:2406.06377v2 (2024)]. The study introduces a new quantum-based technique for quantitative phase microscopy that does not rely on interferometry or scanning, and is intrinsically resilient to background light—a common limitation in classical imaging approaches.

The technique involves illuminating a transparent sample with both photons from a position–momentum entangled pair. One photon is captured in the near field to measure spatial position, while its entangled counterpart is detected in the far field to access momentum information. Owing to the strong spatial correlations provided by quantum entanglement, data from both domains can be acquired simultaneously. By tracking centroid shifts in the far-field momentum distribution as a function of near-field position, the phase gradient of the sample is reconstructed.

This approach achieves an impressive spatial resolution of 2.76 μm, with a phase measurement precision of up to λ/30 and sensitivity reaching λ/100 at a wavelength of 810 nm. Importantly, the use of temporally correlated photon pairs confers intrinsic immunity to fluctuating background illumination—a notable improvement over many classical phase imaging methods.

Overall, the work marks a substantial step forward for quantum phase microscopy, demonstrating a high-resolution, scanning-free, and background-resilient imaging modality within a compact and experimentally accessible setup. See Figure 1 for phase images acquired through the technique. 

Figure 1: Phase imaging of a star test target harnessing quantum imaging correlations. Experimental acquisition by Yingwen Zhang [arXiv:2406.06377v2 (2024)]