A persistent-current-biased and current-actuated tunable coupler for modular quantum network

A critical challenge in building modular quantum networks is the ability to switch high-fidelity on-demand interactions between modules. Currently, the flux sensitivity of Josephson junction circuits is used to bias and actuate these switches. In this talk, we will describe a circuit that eliminates both the flux bias and flux actuation in favor of a persistent current bias and direct current actuation, a design that reduces the switch's static power consumption, actuation energy, flux noise sensitivity, and potential crosstalk to other switches. For the persistent current bias, we demonstrate a protocol to reliably and precisely trap discrete amounts of current associated with 100s of flux quanta. We also show our switch can achieve 50 dB of on/off contrast, process nW scale signals, and transition in less than one nanosecond.