Abstract

Photonic quantum walks (PQWs), realized in lattices of evanescently coupled waveguides, are a powerful platform for demonstrating quantum [1], topological [2] and localization phenomena [3]. The PQW dynamics are captured with a tight-binding Hamiltonian, whose parameters can be engineered with the geometry of the waveguide array. It has been proposed that the two-qubit controlled-NOT (CNOT) gate can be implemented by quantum interference of two-photons in a carefully engineered PQW [4]. Whereas photonic quantum logic gates typically rely on a network of beamsplitters [5], the PQW implements the quantum logic in a single step. While multi-photon experiments in PQWs have been demonstrated [1-3], where photon-photon bunching governs the dynamics, the controlled preparation of entangling logic gates is yet to be experimentally explored.

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