Ryotatsu Yanagimoto & Rajveer Nehra – Ultrafast nonlinear photonics for non-Gaussian quantum info

Optical photons are ideal carriers of quantum information, but the lack of nonlinearity has made all-optical information processing challenging. Currently, nonlinear (i.e., non-Gaussian) quantum operations are only accessible probabilistically, severely limiting the clock rate and scalability of the computational architectures.

In this talk, we propose the use of ultrafast quantum nanophotonics to realize all-optical strong coupling and deterministic non-Gaussian quantum information processing. Intuitively, ultrafast pulses propagating on a nonlinear waveguide act as “flying cavities”, maximally enhancing nonlinear interactions. At the same time, thorough theoretical studies are essential to understand and engineer multimode and mesoscopic quantum dynamics necessarily involved in this regime. First, we introduce a novel spatio-temporal confinement method, temporal trapping, to harness multimode interactions, enabling high-fidelity quantum operations. Then, we discuss the framework of Gaussian Hamiltonian engineering, showing that nonlinear-optical dynamics can naturally be tamed to realize novel quantum functions, e.g., non-Gaussian quantum gate operations and quantum nondemolition measurements.

Finally, we overview recent experimental advances, including the generation and measurement of strongly squeezed states, in dispersion-engineered thin-film lithium niobate platforms, providing prospects for future experimental realizations.

[1] R. Yanagimoto, T. Onodera et al., Phys. Rev. Lett. 124, 240503 (2020).
[2] R. Yanagimoto et al., Optica 9, 1289 (2022).
[3] R. Yanagimoto, R. Nehra et al., PRX Quantum 4, 010333 (2023).
[4] R. Nehra, R. Sekine et al., Science 377, 1333 (2022).
[5] R. Yanagimoto, R. Nehra et al., arXiv:2305.03260.