  Entanglement is a counterintuitive feature of quantum physics that is at the
heart of quantum technology. High-dimensional quantum states offer unique
advantages in various quantum information tasks. Integrated photonic chips have
recently emerged as a leading platform for the generation, manipulation and
detection of entangled photons. Here, we report a silicon photonic chip that
uses novel interferometric resonance-enhanced photon-pair sources, spectral
demultiplexers and high-dimensional reconfigurable circuitries to generate,
manipulate and analyse path-entangled three-dimensional qutrit states. By
minimizing on-chip electrical and thermal cross-talk, we obtain high-quality
quantum interference with visibilities above 96.5% and a maximumly entangled
qutrit state with a fidelity of 95.5%. We further explore the fundamental
properties of entangled qutrits to test quantum nonlocality and contextuality,
and to implement quantum simulations of graphs and high-precision optical phase
measurements. Our work paves the path for the development of multiphoton
high-dimensional quantum technologies.
