On-demand driven dissipation for cavity reset and cooling on a superconducting chip*

In superconducting circuits, a significant source of dephasing error is caused by spurious thermal photons, which introduce entropy in the system. Furthermore, the excess entropy after a measurement places limitations on QEC which typically requires many operations and measurements per logical operation. As a result, rapid and high-fidelity reset procedures for both qubits and readout resonators become essential. While techniques like active feedback provide a way to reduce entropy in these systems, these methods are information based so often are slow, complicated, and introduce additional errors. In this talk, we demonstrate how a cold source of dissipation, usually thought of as a source of decoherence, can be used as a resource to eliminate excess entropy from a system that has unwanted excitations. This active on-demand 'dissipator' provides a way to speed up qubit reset and resonator reset while also enabling active cooling of the resonator. Our 'dissipator' device is a high-frequency parametric coupler that is deliberately made lossy by coupling to an external microwave termination. By parametrically driving the dissipator at the detuning frequency between it and a target mode, we can controllably generate dissipation as well as refrigeration of target modes. We demonstrate improved coherence times of our logical qubit as well as reset of both qubit and its readout resonator, achieving reset rates exceeding 10 MHz.