A high fidelity heralded squeezing gate
Abstract
A universal squeezing gate capable of squeezing arbitrary input states is essential for continuous-variable quantum computation~PRA79062318,PRL112120504. However, in present state-of-the-art techniques~PRA90060302,PRL106240504, the fidelity of such gates is ultimately limited by the need to create squeezed vacuum modes of unbounded energy. Here we circumvent this fundamental limitation by using a heralded squeezing gate. We propose and experimentally demonstrate a squeezing gate that can achieve near unit fidelity for coherent input states. In particular, for a target squeezing of 2.3, we report a fidelity of 98.5\%. This result cannot be reproduced by conventional schemes even if the currently best available squeezing of 15~PRL117110801 is utilised when benchmarked on identical detection inefficiencies. Our technique can be applied to non-Gaussian states and provides a promising pathway towards high-fidelity gate operations and fault-tolerant quantum computation.