Probing light-matter entanglement in the non-perturbative regime of a strongly driven spin-boson system
Milena Grifoni, University of Regensburg
The spin-boson model is an archetype model to study the impact of a thermal reservoir on the coherent dynamics of a two-level quantum particle. When the coupling between qubit and environment crosses a threshold, a transition from coherent to incoherent tunneling between the two qubit eigenstates occurs. At even larger coupling, the dynamics is fully quenched, signaling a strong entanglement of the qubit with the reservoir’s continuum. When the qubit is additionally driven by an intense cw-field, it can further hybridize with the radiation field. In my talk a nonperturbative approach capable to capture both large qubit-reservoir coupling and strong driving will be presented. Furthermore, I will discuss how such complex physics can be studied in a strongly driven flux qubit coupled to the electromagnetic continuum of a one-dimensional waveguide. We shall show that measurements of the transmitted signal give direct access to the renormalization effects from the reservoir. When a strong pump tone is added to the probe signal, the appearance of photon-assisted resonances in the transmission reveals a further entanglement between the damped qubit and the radiation field.