Realization of two-qubit gates with tunable couplers in superconducting circuits

The realization of two-qubit gates with high fidelity and low crosstalk is a key requirement for the scale-up of quantum processors based on superconducting circuits. Two-qubit gates are typically based on either microwave-controlled interactions or on the in-situ tunability of qubit frequencies. Alternative approaches using tunable coupling elements have also been investigated more recently. Here, we report on the design and implementation of a flux-tunable coupler, featuring small residual qubit-qubit interactions when gates are idle. We study gate operations based on both fast DC flux control and parametric flux modulation.