We present a method to prepare non-classical states of the electromagnetic field in a microwave resonator. It is based on a controlled gate that applies a squeezing operation on a SQUID-terminated resonator conditioned on the state of a dispersively coupled qubit. This controlled-squeeze gate, when combined with Gaussian operations on the resonator, is universal. We explore the use of this tool to map an arbitrary qubit state into a superposition of squeezed states. In particular, we target a bosonic code with well-defined superparity which makes photon losses detectable by non-demolition parity measurements. We analyze the possibility of implementing this using state-of-the-art circuit QED tools and conclude that it is within reach of current technologies.
@article{arxiv.2408.08404,
title = {Controlled-squeeze gate in superconducting quantum circuits},
author = {Nicolás F. Del Grosso and Rodrigo G. Cortiñas and Paula I. Villar and Fernando C. Lombardo and Juan Pablo Paz},
journal= {arXiv preprint arXiv:2408.08404},
year = {2025}
}