Mapping a quantum walk by tuning the coupling coefficient

We present a method to map the evolution of photonic quantum walks that is compatible with nonclassical input light. Our approach leverages a newly developed flexible waveguide platform to reconfigure the jumping rate between spatial modes, allowing the observation of a range of evolution times in a chip of fixed length. In a proof-of-principle demonstration, we reconstruct the evolution of photons through a uniform array of coupled waveguides by monitoring the end-face while tuning the device. This approach enables direct observation of mode occupancy at arbitrary resolution, extending the utility of photonic quantum walks for quantum simulations and related applications.