Characterization of iSWAP gate using a Dual-Transmon Coupler

Parametric circuits can implement fast and tunable interactions in multi-mode superconducting circuits. These interactions are typically activated by modulating a tunable coupling device at a linear combination of qubit frequencies, resulting in a strong frequency-selective interaction. One such design is the dual-transmon coupler (DTC) device, which facilitates strong exchange interaction between the data qubits while minimizing  ZZ coupling  simultaneously. This makes the DTC especially useful for realizing high-fidelity two-qubit gate operations such as iSWAP or CZ.

In this talk, we present the implementation and experimental characterization of the iSWAP gate on a DTC device. First, we briefly discuss the modular design and characteristics of the device. Then, we present a calibration routine for pulse optimization of the iSWAP that allows amplification and precise calibration of the unknown pulse parameters. We confirm the high gate fidelity and perform a detailed error budgeting for the iSWAP gate, with process tomography, randomized benchmarking (RB), as well as gate set tomography (GST).

[1] Physical Review Applied 19.6 (2023), 064043