Design Considerations for CZ Gates with Short-Lived Couplers in Superconducting Qubits

Implementing high-fidelity two-qubit gates in superconducting circuits often requires balancing strong coupling for speed with decoherence introduced by couplers. We theoretically investigate CZ gate schemes in a tunable coupler architecture consisting of two transmon qubits coupled through a gatemon with an asymmetrically poor lifetime. We find that the regime of strong qubit-coupler interaction and large detuning should allow gates with competitive fidelity despite lagging gatemon coherence. While this work focuses on a gatemon-mediated interaction, our results highlight general strategies for optimizing coupler-based architectures in multi-qubit superconducting systems.