Design of a Josephson Travelling Wave Photon Detector

High-fidelity and wide bandwidth single microwave photon detection remains a challenge for quantum information experiments. Here, we investigate a new design for the Josephson travelling wave photon detector[1,2], a circuit QED based detector which promises high fidelity, non-destructive, and broadband detection of microwave photons. In this design, the broadband detection relies on nonlinear interactions between signal and probe photons in coupled transmission lines. We engineer a cross-Kerr interaction using both quartons and transmons to eliminate self-Kerr and enhance the readout efficiency. By measuring a phase shift on the probe photons, we can deduce the signal photon number with high fidelity.

[1] A. L. Grimsmo, B. Royer, J. Bourassa, N. Didier, and A. Blais, “Quantum non-demolition and high-efficiency detection of traveling microwave photons-part 2,” in APS Meeting Abstracts, 2017.
[2] A. L. Grimsmo, B. Royer, J. M. Kreikebaum, K. O’Brien, I. Siddiqi, and A. Blais, “Quantum metamaterial for nondestructive microwave photon counting,” Unpublished, 2019.