High-speed imaging of spatiotemporal correlations in Hong-Ou-Mandel interference

Abstract

Two-photon interference is widely used in quantum information processing, e.g., state engineering and designing quantum gates, as well as in quantum sensing and metrology. This includes the generation and characterization of N00N states, which provide a phase measurement sensitivity that is beyond the shot-noise limit. There have been numerous efforts in generating N00N states with a photon number higher than 2, since their measurement sensitivity increases with N. Both photon number state and modal (temporal, spectral, and spatial) properties of light offer advantages in sensing, where the latter is achieved through mode-multiplexed measurements. Here, we experimentally demonstrate, with the aid of a recently developed photon-detection technology, measurement and characterization of up to tera-mode spatiotemporal correlations in two-photon interference and use it to generate high-dimensional two-photon N00N-states, which can be advantageous for multiphase estimation. We observe a high bi-photon interference and coalescence visibility of ∼ 64% and ∼ 88% for a tera (10 12 ) and 0.2 tera (2 × 10 11 ) spatiotemporal modes, respectively. These results open up a route for practical applications of using the spatiotemporal degrees of freedom in two-photon interference, and in particular, for quantum sensing and communication.