Post-fabrication frequency trimming of coplanar-waveguide resonators in circuit QED quantum processors

We present the use of a set of airbridges to trim the frequency of microwave coplanar-waveguide (CPW) resonators post-fabrication. This method is compatible with the fabrication steps of conventional CPW airbridges and crossovers and increases device yield by allowing compensation of design and fabrication uncertainty with 100 MHz range and 10 MHz resolution. We showcase two applications in circuit QED. The first is the elimination of frequency collisions between resonators intended to readout different transmons by frequency-division multiplexing. The second is frequency matching of readout and Purcell-filter resonator pairs. Combining this matching with transmon frequency trimming by laser annealing reliably achieves fast and high-fidelity readout across 17-transmon quantum processors.

Automated summary

This paper presents a method that uses a set of airbridges to trim the frequency of microwave coplanar-waveguide (CPW) resonators post-fabrication. The method is compatible with conventional CPW airbridges and crossovers, and it increases device yield by compensating for design and fabrication uncertainty with 100 MHz range and 10 MHz resolution. Two applications in circuit QED are showcased: elimination of frequency collisions between resonators for different transmons by frequency-division multiplexing, and frequency matching of readout and Purcell-filter resonator pairs. The combination of matching and transmon frequency trimming achieves fast and high-fidelity readout across 17-transmon quantum processors.