Gaussian conversion protocols for cubic phase state generation: Part 2

In order to achieve universality in quantum computation with continuous-variable systems, cubic phase states play a crucial role, as they can promote a Gaussian set of operations to universal quantum computation. The generation of these states has however been challenging in quantum optics, due to the weakness of the non-linearities that are typically available in that domain. In this talk, we introduce a probabilistic Gaussian conversion protocol that allows one to prepare a cubic phase state by starting from a trisqueezed state that has been realized experimentally with microwave circuits [Sandbo Chang et al., Phys.Rev. X10, 011011 (2020)], and using Gaussian operations and measurement. The measurement is conditioned on a specific outcome, which renders the protocol probabilistic. We analyze the performance of our conversion protocol in terms of fidelity of conversion and success probability. Furthermore, we show that our probabilistic conversion protocol allows for achieving a higher conversion fidelity, as compared to the fidelity achievable with deterministic Gaussianconversion protocols.