Integrated phononic waveguide on thin-film lithium niobate on diamond

Applied Physics Letters (2025)

 

In this paper, scientists built extremely small waveguides that carry sound waves — specifically, tiny vibrations called phonons — using a thin layer of lithium niobate placed on top of a diamond crystal. This combination takes advantage of lithium niobate’s ability to convert electrical signals into sound and diamond’s ability to carry sound very quickly while being compatible with quantum sensors.

They tested a 100-micrometer-long waveguide that worked efficiently both at room temperature and at very cold temperatures (about 4 Kelvin). The device showed over 50% efficiency at a frequency of 2.8 gigahertz, which means it can convert electrical signals into guided sound waves very efficiently. This work is an important step toward building hybrid quantum systems where vibrations in the diamond can connect with quantum defects — tiny atomic-scale features that can sense strain or store quantum information.

The paper’s authors are Sultan Malik, Felix Mayor, Wentao Jiang, Hyunseok Oh, Carl Padgett, Viraj Dharod, Jayameenakshi Venkatraman, Ania Jayich and Amir Safavi-Naeini, who conducted their work at Stanford University and the University of California, Santa Barbara