  Large-amplitude squeezed cat and high-quality Gottesman-Kitaev-Preskill (GKP)
states are powerful resources for quantum error correction. However, previous
schemes in optics are limited to low success probabilities, small amplitudes,
and low squeezing. We overcome these limitations and present scalable schemes
in optics for the deterministic preparation of large-amplitude squeezed cat
states using only Gaussian operations and photon-number measurements. These
states can be bred to prepare high-quality approximate GKP states, showing that
GKP error correction in optics is technically feasible in near-term
experiments.
