Native two-qubit gates in fixed-coupling, fixed-frequency transmons beyond cross-resonance interaction

Understand

Fixed-frequency superconducting qubits demonstrate remarkable success as platforms for stable and scalable quantum computing.

• Cross-resonance gates have been the workhorse of fixed-coupling, fixed-frequency superconducting processors, leveraging the entanglement generated by driving one qubit resonantly with a neighbor's frequency to achieve high-fidelity, universal CNOTs.
• Here, we use on-resonant and off-resonant microwave drives to go beyond cross-resonance, realizing natively interesting two-qubit gates that are not equivalent to CNOTs.
• In particular, we implement and benchmark native ISWAP, SWAP, $\sqrt{\text{ISWAP}}$, and BSWAP gates.