Large On:Off ratio two-qubit coupler in circuit QED

Tunable two-qubit couplers are important elements of the circuit QED architecture for quantum information processing as they enable, on demand, qubit-qubit entanglement generation. Their performance is typically assessed in the “on-regime” where the focus lies on the fidelity of gate operations and their execution time. Yet, even during idle times, couplers can introduce undesired interactions which detrimentally affect other qubit operations. In order to mitigate these deleterious effects, a large on-off ratio coupler was introduced by Leroux et al [1]. Fundamentally, this coupler allows for the exponential suppression of all two-qubit interactions during the off state, effectively mitigating undesired effects. In this work, we propose and fully characterize a simplified implementation of a large on:off ratio coupler. Our approach simplifies the original proposal [1] since no higher-order wave mixing is needed, while keeping its advantages, namely the exponential suppression of residual interactions.