Optimizing readout hardware for large scale quantum computers

In a superconducting quantum computer, each microwave readout line requires low noise parametric amplifiers, circulators, and filters. These are expensive resources, not only in cost but also in weight and size. In larger systems it is increasingly necessary to use frequency multiplexed readout tones such that many qubits can be measured with a single line. This in turn requires superconducting parametric amplifiers that operate with broad bandwidth and high saturation power, while maintaining near quantum limited noise performance. In this talk we will compare several different varieties of amplifier from the perspective of device performance, fabrication difficulty, yield, and wiring complexity. We will also report on performance metrics for these architectures in our superconducting qubit processors.