Science Perspective: Catching the quantum sound wave

Rusko Ruskov, Charles Tahan

An ultrasound transducer (“the wand”) both creates and detects sound waves that travel through the body to create images of internal organs or precious cargo (see the figure, panel A). This compact device is made possible with piezoelectric crystals that expand or contract in response to an applied voltage and thus interconvert sound waves and electrical signals. Because sound travels relatively slowly, there is time to process the reflected pulses and display an image in real time. These measurements are in the realm of classical physics, but sound could also play a useful role in quantum-based devices. On page 207 of this issue, Gustafsson et al. (1) take a major step toward that goal, demonstrating a system in which a specially engineered artificial atom in the form of a superconducting quantum bit (qubit) couples to propagating surface acoustic waves on a chip. This soundmatter system shows evidence of quantum behavior.

Catching the quantum sound wave (

Charles Tahan
Physicist in Washington, D.C.