Squeezing and Multimode Entanglement of Surface Acoustic Wave Phonons

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.

Automated summary

Exploiting multiple modes in a quantum acoustic device offers potential applications in quantum information, such as quantum simulation and continuous-variable quantum computing. By developing a multimode surface acoustic wave (SAW) resonator with a integrated SQUID, we demonstrated two-mode squeezing of SAW phonons and four-mode multipartite entanglement.