Fabrication and Packaging of Superconducting Radio-frequency Quantum Upconverters

The radio-frequency quantum upconverter (RQU) is a superconducting flux-tunable resonator designed to sensitively upconvert low-frequency electromagnetic signals to microwave frequencies. To this end, the RQU requires sufficient mitigation of noise to (1) resolve low-frequency sidebands and (2) control and limit noise sources to those effectively mitigated by backaction evasion techniques. In this talk, we will discuss design, fabrication, and packaging improvements made for the RQU to lower its background magnetic field environment and improve noise. In particular, we will discuss improvements to the RQU's multi-layer fabrication, including the addition of bandaging layers and crossover coil design. We will also discuss efforts to reduce the magnetic field environment and infrared radiation noise through the use of shielding, and compare this against other state-of-the-art superconducting device packaging.