On-Demand Control and Dissipation of Bosonic Modes via Strongly Driven Transmons

Superconducting quantum circuits face a fundamental catch-22:bosonic modes are excellent for storing quantum information because of theirincredibly long lifetimes, but those lifetimes require them to be highlyisolated. Crucially, this means isolating them from non-linear elements—likequbits—which are the exact tools required to achieve full, universal quantumcontrol. This strict separation makes it notoriously difficult to rapidlymanipulate or reset the memory mode.

In this seminar, I will present a unified approach to bypass thisbottleneck. The key is to keep a transmon qubit in a very weakly coupled regimeby default, perfectly preserving the memory mode's pristine isolation. However,by applying a strong microwave drive to the transmon, we can temporarily bridgethat gap, turning the qubit into a highly tunable "switch." Thisallows us to turn on demand strong, effective interactions when we need themfor control or engineered dissipation.

The main focus is an experimental demonstration of Rabi-DrivenReset (RDR). By combining a resonant Rabi drive with appropriately chosensideband drives, the dispersive qubit–mode interaction is converted into aresonant dressed-state exchange. This opens a tunable dissipation channel thatcools a memory mode into a cold readout bath without measurement or feedback,enabling rapid removal of thermal and multi-photon populations. We then brieflyconnect the same driven-dressed-state toolbox to strong qubit-mediatedparametric interactions, including conditional single- and two-mode squeezing.Together, these techniques provide a scalable route to fast bosonic statepreparation, cooling, and gate primitives within the same circuit-QEDarchitecture.