Phonons are the quantum particles of sound waves in solids, representing the collective motion of astronomical numbers of atoms. While initially phonons served as a convenience for calculations of heat capacity, heat transport and particle scattering, recent developments in my group have shown that phonons can in fact be used as carriers of quantum information, with properties very similar to photons. In this talk I will describe a series of experiments, in which my group has used surface acoustic waves controlled and detected by superconducting qubits for the on-demand generation, storage, and detection of individual microwave-frequency phonons in an acoustic resonator; used phonons to transmit quantum states and generate quantum entanglement; demonstrated a single-phonon interferometer and a quantum information process known as “quantum erasure”; and most recently used phonons with an acoustic beamsplitter to demonstrate the Hong-Ou-Mandel effect with phonons, beautifully illustrating the wave-particle duality fundamental to quantum mechanics. Interestingly, this last development points to the possible development of a phonon-based version of linear optical quantum computing, which could be called linear mechanical quantum computing.
