Long-lived and Efficient Optomechanical Memory for Light

We demonstrate a memory for light based on optomechanically induced transparency. We achieve a long storage time by leveraging the ultralow dissipation of a soft-clamped mechanical membrane resonator, which oscillates at MHz frequencies. At room temperature, we demonstrate a lifetime T1 23 ms and a retrieval efficiency eta 40% for classical coherent pulses. We anticipate the storage of quantum light to be possible at moderate cryogenic conditions (T 10 K). Such systems could find applications in emerging quantum networks, where they can serve as long-lived optical quantum memories by storing optical information in a phononic mode.