Acoustic Radiation From a Superconducting Qubit: From Spontaneous Emission to Rabi Oscillations

A phonon (quantized vibration of a crystalline medium) is much shorter in wavelength than a photon of the same frequency. This length-scale reduction offers an opportunity to achieve higher density of quantum information storage, and may open a path to scalable implementations of superconducting quantum processors. However, the smallness of the acoustic wavelength also poses a challenge: It may result in fast qubit decoherence via an unintentional emission of phonons. The authors demonstrate how to circumvent such spontaneous emission and attain quantum coherent coupling of a qubit to an isolated phonon mode.