My group has been developing individual itinerant phonons for possible applications to quantum computing and quantum sensing. Using superconducting qubits as deterministic sources and detectors of individual microwave-frequency phonons, we can create individual phonons in a mechanical resonator; generate quantum entangled states between phonons in two physically separate mechanical resonators; transmit quantum states between superconducting qubits via phonons, and generate quantum entanglement by sharing “half-phonons” between two superconducting qubits. By assembling a single-phonon interferometer, we have also demonstrated the acoustic version of the Hong-Ou-Mandel effect from quantum optics, which in turn has allowed us to demonstrate coherent one- and two-phonon classically-controlled phase gates. These point to the possible development of a phonon-based architecture for quantum computing, in which phonons, generated as “throw-away” qubits, can in principle allow scaling to very large numbers of qubits at no additional expense. I will also briefly describe our recent efforts to use this technology for quantum sensing.

References:
[1] H. Qiao et al., “Splitting phonons: Building a platform for linear mechanical quantum computing,” Science 380, 1030-1033 (2023) https://www.science.org/doi/10.1126/science.adg8715
[2] E. Dumur et al., “Quantum communication with itinerant surface acoustic wave phonons”, npj Quantum Information 7, 1-5 (2021) https://doi.org/10.1038/s41534-021-00511-1
[3] A. Bienfait et al., “Quantum erasure using surface acoustic phonons”, Phys. Rev. X 10, 021055 (2020) https://journals.aps.org/prx/abstract/10.1103/PhysRevX.10.021055
[4] A. Bienfait et al., “Phonon-mediated quantum state transfer and remote qubit entanglement”, Science 364, 368-371 (2019) http://science.sciencemag.org/cgi/content/full/364/6438/368
[5] M.-H. Chou*, H. Qiao* et al., “Deterministic multi-phonon entanglement between two mechanical resonators on separate substrates,” Nature Comm. 16, 1450 (2025)
[6] K. J. Satzinger et al., “Quantum control of surface acoustic wave phonons”, Nature 563, 661–665 (2018) https://www.nature.com/articles/s41586-018-0719-5