Limits of Broadband Amplification in Resonant Josephson Parametric Amplifiers*

High-fidelity, frequency multiplexed, quantum non-demolition qubit measurement is critical to error correction and feedback in large-scale quantum computers. High fidelity readout requires a short and strong pulse transiting the qubit's measurement mode which is then processed by a necessarily high bandwidth, high saturation power, quantum-limited amplifier; multiplexing simply expands the required bandwidth by the number of channels to be amplified. Previous work has shown high saturation power in single-mode devices based on radio frequency Superconducting QUantum Interference Device (RF-SQUID) arrays with modest bandwidth (~50-100 MHz). In this talk we present the design of a planar broadened RF-SQUID array amplifier, targeting 500-1000 MHz of total bandwidth in a degenerate design, and investigate limits of achievable bandwidth. Given our high saturation power, and concomitant strong pump, our amplifiers utilize a voltage pump delivered via a diplexer on the signal port. We will present progress in fabricating devices and explore the limits imposed by interaction with the external environment as well as the impact of the choice of filter network prototype on pump requirements, noise performance, and intermodulation products for the amplifier.