On-demand generation and characterization of a microwave time-bin qubit

  1. Jesper Ilves,
  2. Shingo Kono,
  3. Yoshiki Sunada,
  4. Shota Yamazaki,
  5. Minkyu Kim,
  6. Kazuki Koshino,
  7. and Yasunobu Nakamura
Superconducting circuits offer a scalable platform for the construction of large-scale quantum networks where information can be encoded in multiple temporal modes of propagating microwaves.
Characterization of such microwave signals with a method extendable to an arbitrary number of temporal modes with a single detector and demonstration of their phase-robust nature are of great interest. Here we show the on-demand generation and Wigner tomography of a microwave time-bin qubit with superconducting circuit quantum electrodynamics architecture. We perform the tomography with a single heterodyne detector by dynamically changing the measurement quadrature with a phase-sensitive amplifier independently for the two temporal modes. By generating and measuring the qubits with hardware lacking a shared phase reference, we demonstrate conservation of phase information in each time-bin qubit generated.