EE Devices Seminar- Eli Levenson-Falk, USC

Dissipation in superconducting quantum devices is typically thought of as a harmful effect, causing energy loss that can decohere quantum states and cause process errors. However, dissipation can also be a useful resource, removing entropy from a system and allowing us to drive it to a desired state. I present our recent results creating driven, on-demand dissipation in a superconducting qubit system. Our "dissipator" device consists of a tunable coupler that can be driven parametrically to induce resonant coupling between a target mode and a lossy bath, implementing a quantum refrigeration process. We have used this dissipator to cool a readout resonator to its ground state more than an order of magnitude faster than passive cooling would allow, resetting the system after a qubit measurement. We have also used it to cool the resonator in the presence of environmental noise, preserving the coherence of a qubit coupled to the cavity even at elevated cavity temperature. Our setup supports qubit coherence for longer than 1 ms even with a cavity temperature above 100 mK. I will also discuss present future applications of the dissipator to stabilize nontrivial states and emulate quantum environments.