Nonclassical correlations between single photons and phonons from a mechanical oscillator
Author(s): R. Riedinger, S. Hong, R. A. Norte, J. A. Slater, J. Shang, A. Krause, V. Anant, M. Aspelmeyer, S. Gröblacher
DOI Number: 10.1038/nature16536
Link: Link to publication
Interfacing a single photon with another quantum system is a key capability in modern quantum information science. It allows quantum states of matter, such as spin states of atoms, atomic ensembles or solids, to be prepared and manipulated by photon counting and, in particular, to be distributed over long distances. Such light-matter interfaces have become crucial for fundamental tests of quantum physics as well as for realizations of quantum networks. Here we report nonclassical correlations between single photons and phonons -- the quanta of mechanical motion -- from a nanomechanical resonator. We implement a full quantum protocol involving initialization of the resonator in its quantum ground state of motion and subsequent generation and readout of correlated photon-phonon pairs. The observed violation of a Cauchy-Schwarz inequality is clear evidence for the nonclassical nature of the generated mechanical state. Our results show the availability of on-chip solid-state mechanical resonators as light-matter quantum interfaces. The demonstrated performance enables studies of macroscopic quantum phenomena as well as applications in quantum communication, as quantum memories, and as quantum transducers.