Two-Dimensional Quantum Walk of Correlated Photons

TL;DR

This paper demonstrates a genuine two-dimensional quantum walk with correlated photons on a large-scale triangular photonic lattice, enabling complex quantum simulations and computations beyond classical capabilities.

Contribution

It presents the first 2D multi-photon quantum walk on a triangular lattice, achieving high-dimensional encoding and large-scale non-classical interference observations.

Findings

Mapped to a 37x37 dimensional state space

Observed over 600 non-classical interferences simultaneously

Violates classical limits up to 57 standard deviations

Abstract

Quantum walks in an elaborately designed graph, is a powerful tool simulating physical and topological phenomena, constructing analog quantum algorithms and realizing universal quantum computing. Integrated photonics technology has emerged as a versatile platform to implement various quantum information tasks and a promising candidate to perform large-scale quantum walks. Both extending physical dimensions and involving more particles will increase the complexity of the evolving systems and the desired quantum resources. Pioneer works have demonstrated single particle walking on two-dimensional (2D) lattices and multiple walkers interfering on a one-dimensional structure. However, 2D multi-particle quantum walk, genuinely being not classically simulatable, has been a vacancy for nearly ten years. Here, we present a genuine 2D quantum walk with correlated photons on a triangular photonic lattice, which can be mapped to a state space up to 37X37 dimensions. This breaks through the physically restriction of single-particle evolution, which can encode information in a large space and constitute high-dimensional graphs indeed beneficial to quantum information processing. A site-by-site addressing between the chip facet and the 2D fanout interface enables an observation of over 600 non-classical interferences simultaneously, violating a classical limit up to 57 standard deviations. Our platform offers a promising prospect for multi-photon quantum walks in a large-scale 2D arrangement, paving the way for practical quantum simulation and quantum computation beyond classical regime.