Engineering non-Gaussian bosonic gates through quantum signal processing
Phys. Rev. A 114, 032608 – Published 11 September, 2026
DOI: https://doi.org/10.1103/gdbf-cjz4
Abstract
Non-Gaussian operations are essential for most bosonic quantum technologies. Yet, realizable non-Gaussian gates are rather limited in type and generally suffer from accuracy-duration trade-offs. In this work, we propose to use quantum signal processing (QSP) techniques to engineer non-Gaussian gates on hybrid qumode-qubit systems. For systems with dispersive coupling, our scheme can generate a non-Gaussian gate that produces a phase shift depending on the modulus of the boson number. This gate reproduces the selective number-dependent arbitrary phase gates under certain parameter choices, but with higher accuracy within a short, fixed, and excitation-independent interaction time. The gate unlocks different applications, for example, in entangling logical qudits and deterministically generating multicomponent cat states. Additionally, our versatile QSP formalism can be extended to systems with other interactions and also engineer nonunitary operations, such as noiseless linear amplification and generalized-parity measurement.
