Scalable ultrafast quantum information processors in nanophotonics

Optical photons are excellent quantum information carriers, but weak optical nonlinearity poses significant challenges to the scalability and computational capabilities of these systems. Currently, only probabilistic methods can achieve nonlinear quantum operations crucial for universality and fault tolerance, restricting the clock speed and making it challenging to scale due to significant resource overhead. Ultrafast quantum nanophotonics with second-order optical nonlinearity presents a potential solution to overcome these challenges. In this talk, we will discuss recent experimental advances, including the on-chip generation and measurement of ultra-broadband squeezed states, all-optical realizations of switching and nonlinear functions for ultrafast feedforward operations, and widely tunable optical parametric oscillators in an emergent thin-film lithium niobate on insulator platform. We further delve into how the enhanced optical nonlinearity can enable novel functionalities such as photon-number-resolving measurements and deterministic quantum state engineering, offering a practical path to scalable, fault-tolerant quantum information processors room-temperature.