The generation of non-Gaussian quantum states is a key requirement for universal continuous-variable quantum information processing. We report the experimental generation of large-amplitude squeezed coherent-state superpositions (squeezed cat states) on free-space optical pulses, reaching an amplitude of α=2.47, which, to our knowledge, exceeds all previously reported values. Our protocol relies on the controlled mixing of the Fock states ∣1⟩ and ∣2⟩ through a tunable beam splitter, followed by heralding via homodyne detection. The resulting state displays three well-resolved negative regions in its Wigner function and achieves a fidelity of 0.53 with the target state ∝S^(z)(∣α⟩−∣−α⟩), with α=2.47 and squeezing parameter z=0.56. These results constitute a significant milestone for temporal breeding protocols and for the iterative generation of optical GKP states, opening new perspectives for scalable and fault-tolerant photonic quantum architectures.
@article{arxiv.2601.09672,
title = {Generation of Large Coherent-State Superpositions in Free-Space Optical Pulses},
author = {Lucas Caron and Hector Simon and Hugo Basset and Romaric Journet and Rosa Tualle-Brouri},
journal= {arXiv preprint arXiv:2601.09672},
year = {2026}
}