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Nanofabrication, packaging, and characterization of quantum limited amplifiers
O'Brien, Kevin - Massachusetts Institute of Technology
Presentation on Thursday, May 2, 2024, noon
Location: MIT CUA Room (26-214)
Josephson junction based travelling wave parametric amplifiers (JTWPAs) are widely used in cQED experiments for high-fidelity readout of superconducting qubits over a large bandwidth. We develop a fabrication process in MIT.nano for superconducting circuits containing thousands of Josephson junctions with high uniformity and yield. Such amplifiers are sensitive to impedance mismatch and spurious package modes, hindering performance above 12 GHz. 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 in the T.J. Rodgers RLE Lab, and well-matched to above 20 GHz. Finally, we report noise characterization results of a low-loss, qubit-fabrication-compatible Floquet TWPA device using both the circuit-QED and the waveguide-QED (wQED) power calibration methods