Exploiting multiple modes in a quantum acoustic device could enable applications in quantum information in a hardware-efficient setup, including quantum simulation in a synthetic dimension and continuous-variable quantum computing with cluster states.We develop a multimode surface acoustic wave (SAW) resonator with a superconducting quantum interference device (SQUID) integrated in one of the Bragg reflectors. The interaction with the SQUID-shunted mirror gives rise to coupling between the more than 20 accessible resonator modes. We exploit this coupling to demonstrate two-mode squeezing of SAW phonons, as well as four-mode multipartite entanglement. Our results open avenues for continuous-variable quantum computing in a compact hybrid quantum system.
@article{arxiv.2007.05826,
title = {Squeezing and multimode entanglement of surface acoustic wave phonons},
author = {Gustav Andersson and Shan W. Jolin and Marco Scigliuzzo and Riccardo Borgani and Mats O. Tholén and J. C. Rivera Hernández and Vitaly Shumeiko and David B. Haviland and Per Delsing},
journal= {arXiv preprint arXiv:2007.05826},
year = {2022}
}