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.
@article{arxiv.1912.03006,
title = {On-demand generation and characterization of a microwave time-bin qubit},
author = {Jesper Ilves and Shingo Kono and Yoshiki Sunada and Shota Yamazaki and Minkyu Kim and Kazuki Koshino and Yasunobu Nakamura},
journal= {arXiv preprint arXiv:1912.03006},
year = {2020}
}