Novel wideband Purcell filters for circuit QED

On-chip Purcell filters — which suppress the spontaneous emission of superconducting qubits into their control and readout lines — are a key component of many quantum processors. Here we present a new design methodology for Purcell filters, which can have compact size, while also maintaining large frequency bandwidths for both qubits and readout resonators — with extensive control over the frequency scaling of readout resonator linewidths. We experimentally demonstrate the functionality of these filters in devices containing transmon qubits.