Multipartite entanglement in a microwave frequency comb

  1. Shan W. Jolin,
  2. Gustav Andersson,
  3. J. C. Rivera Hernández,
  4. Ingrid Strandberg,
  5. Fernando Quijandría,
  6. Joe Aumentado,
  7. Riccardo Borgani,
  8. Mats O. Tholén,
  9. and David B. Haviland
Significant progress has been made with multipartite entanglement of discrete qubits, but continuous variable systems may provide a more scalable path toward entanglement of large ensembles.
We demonstrate multipartite entanglement in a microwave frequency comb generated by a Josephson parametric amplifier subject to a bichromatic pump. We find 64 correlated modes in the transmission line using a multifrequency digital signal processing platform. Full inseparability is verified in a subset of seven modes. Our method can be expanded to generate even more entangled modes in the near future.