  We report the observation of Electromagnetically Induced Transparency (EIT)
of a mechanical field, where a superconducting artificial atom is coupled to a
1D-transmission line for surface acoustic waves. An electromagnetic microwave
drive is used as the control field, rendering the superconducting transmon
qubit transparent to the acoustic probe beam. The strong frequency dependence
of the acoustic coupling enables EIT in a ladder configuration due to the
suppressed relaxation of the upper level. Our results show that superconducting
circuits can be engineered to interact with acoustic fields in parameter
regimes not readily accessible to purely electromagnetic systems.

Quantum Physics