Loss-aware pulse sequence optimization for generating photonic Fock states

Abstract

We investigate the preparation of frequency-tunable photonic Fock states in a hybrid cavity system consisting of a nonlinear medium and a two-level system. Employing a gradient-based optimization approach, we construct multipulse driving protocols that control the system dynamics through pulse amplitudes, phases, and inter-pulse delays. Assuming unitary dynamics, the optimized sequences enable near-deterministic preparation of low-photon-number Fock states. We extend the optimization framework to open-system dynamics by modeling atomic decay and photon loss within the Lindblad master equation. This allows us to identify pulse sequences that exhibit enhanced robustness against dissipation compared to those optimized under idealized assumptions. Furthermore, we find that optimal pulse sequences obey strict constraints on relative phases, which are limited to values of 0 or $π$. These phase restrictions are supported by an analytical study that investigates a simple two-pulse sequence treating the second pulse perturbatively.