Splitting phonons: Building a platform for linear mechanical quantum computing

Linear optical quantum computing provides a desirable approach to quantum computing, with only a short list of required computational elements. The similarity between photons and phonons points to the interesting potential for linear mechanical quantum computing using phonons in place of photons. Although single-phonon sources and detectors have been demonstrated, a phononic beam splitter element remains an outstanding requirement. Here we demonstrate such an element, using two superconducting qubits to fully characterize a beam splitter with single phonons. We further use the beam splitter to demonstrate two-phonon interference, a requirement for two-qubit gates in linear computing. This advances a new solid-state system for implementing linear quantum computing, further providing straightforward conversion between itinerant phonons and superconducting qubits.

Automated summary

Linear optical quantum computing is an ideal approach to quantum computing, requiring only a small number of computational elements. The similarity between photons and phonons suggests the potential for using phonons instead of photons in linear mechanical quantum computing. In this study, we demonstrate a beam splitter element with single phonons by using two superconducting qubits for full characterization. We also show two-phonon interference using the beam splitter, a requirement for two-qubit gates in linear computing. This advances a new solid-state system for implementing linear quantum computing and provides a straightforward conversion between itinerant phonons and superconducting qubits.