Engineers Build a Chip Where the Signals Are Sound, Not Light

Engineers at Virginia Tech and the University of Virginia have built a chip platform that carries microwave-frequency sound waves with little loss, with the guiding channels, the power splitters and the resonators all working on the same material. Communications Engineering, a Nature-family journal, published the open-access paper Sept. 30, 2026; the journal says a final version will replace this peer-reviewed one.

The paper presents the circuits as building blocks, not a finished device. The authors say such circuits could open work in microwave acoustics and in quantum phononics, which uses single packets of sound to carry quantum information, and in chips that join sound to light, superconducting quantum bits and defects in solids.

The platform is a patterned thin film of silicon nitride on a lithium niobate base. For the waveguides, the channels that carry the waves, the authors report a frequency-quality factor product of up to 4.22 × 10¹³; the higher that figure, the less energy a wave loses as it travels. Directional couplers, which move power from one channel into another, ran at 3.5-dB insertion loss, and ring resonators reached a loaded quality factor of up to 17,925.

The team then built an oscillator at 1 GHz around one of the ring resonators and measured its phase noise, a measure of how steady the tone is, at −159.0 dBc/Hz at a 100-kHz offset.

The authors note that phononic devices have been built on several different materials, and that no single platform has yet handled every job well at once: guiding waves with low loss, holding them in resonators that ring for a long time, modulating them, and converting efficiently between electrical signals and sound.

The three equal first authors are Jun Ji, Joseph G. Thomas and Zichen Xi, with Jun Ji and Linbo Shao of Virginia Tech as the corresponding authors. Fabrication was carried out at the Center for Nanophase Materials Sciences, a Department of Energy user facility.