Broadened Resonant Josephson Parametric Amplifiers for Frequency Multiplexed Readout

Large superconducting quantum systems require broadband, high saturation power, highly linear, quantum-limited first stage amplifiers to support simultaneous high fidelity readout of many qubits. Resonant Josephson Parametric Amplifiers (JPAs) are well known to add very little noise, and can be engineered with high power handling, but typically have only 10s of MHz bandwidths – a fraction of what is necessary for frequency multiplexed readout. This work focuses on broadening the gain response of resonant JPAs using a matching filter network to engineer the impedance seen by the amplifier. We show the design and iteration process for a broadband resonant JPA device with a 3-pole, mixed lumped and distributed element Chebyshev matching filter, designed to have a fractional bandwidth of 15% at an operating frequency of 6.5 GHz. We will discuss preliminary device results, including broadband device response as a function of gain, as well as the role stray inductance plays in the filter and amplifier core modes.