Two dimensional multiphoton Quantum Walk in transverse momentum of light

Quantum walks (QWs) represent a powerful resource in different fields of physics due to its potential for simulating complex topological systems, paving the way to universal quantum computation. Moreover, two-dimensional QWs prove to outperform in the realization of quantum research algorithms and in the simulation of topological characteristics with respect to the one-dimensional counterpart. We present an innovative platform feasible for the realization of two-dimensional multiphoton QW in the transverse momentum of light. The key element of the platform is a new device called G-plate. When the photons propagate through these devices, they acquire a complex internal structure in the transverse momentum space. We experimentally realize the three-step dynamic of two walkers in different initial positions on the lattice within the quantum regime. Our platform allows us to control the degree of indistinguishability of photons, allowing us to investigate the bosonic behavior of two photons in the QW dynamic. As a future prospect, our platform could be exploited for the implementation of more complex schemes using multiphoton interference, such as multiphoton Boson sampling and the hybrid entanglement state engineering.