High frequency microwave packaging for Josephson traveling wave parametric amplifiers*

The detection of single-photon microwave signals above 12 GHz is of significant interest for quantum sensing applications in neutrino mass measurement, dark matter searches, and quantum information processing. Below 12 GHz, quantum-limited amplification can be achieved with high-gain, broadband, and low-noise Josephson traveling wave parametric amplifiers (JTWPAs). However, standard microwave packaging for JTWPAs introduce package modes above 12 GHz, as well as impedance mismatches at the connectors and wirebonding locations that hinder the performance of JTWPAs. Here we present an approach to high frequency microwave package design that optimizes package and connector modes, minimizes wirebonds on interposer chips, and employs signal-line compensation strategies for better impedance matching throughout. The package is modular, easily prototyped, and well-matched up to 27 GHz. This package will be deployed with a K band JTWPA tailored to the Project 8 neutrino mass measurement experiment, which will enable the detection of cyclotron radiation from single electrons with a signal-to-noise ratio improvement of an order of magnitude compared to current HEMT amplifiers. Since this design features low reflection and minimal spurious modes over a broad range of frequencies, this package can also be tailored to suit a wide range of superconducting quantum devices.