Abstract : In this talk I will discuss our work on the interaction between stationary qubits and moving photons in a regime in which we cannot apply the Rotating Wave Approximation (RWA). This regime is of interest for a variety of physical systems, but I will focus on superconducting quantum circuits, where photons and qubits are excitations of similar subsystems and exhibit very strong coupling. The talk will be centered around the theoretical modelization [2,3] of such strong interactions, from the study of spontaneous emission to scattering experiments, but will provide some insight on the related experimental detection of this new light-matter coupling regime by Forn-Díaz et al [1]

[1] Ultrastrong coupling of a single artificial atom to an electromagnetic continuumP. Forn-Díaz, J. J. García-Ripoll, B. Peropadre, M. A. Yurtalan, J.-L. Orgiazzi, R. Belyansky, C. M. Wilson, A. Lupascu, to appear in Nat. Phys [2] Nonequilibrium and nonperturbative dynamics of ultrastrong coupling in open linesB. Peropadre, D. Zueco, D. Porras, J. J. Garcia-Ripoll, PRL 111, 243602 (2013) [3] Dynamical polaron ansatz : a theoretical tool for the ultra-strong coupling regime of circuit QEDGuillermo Díaz-Camacho, Alejandro Bermudez, Juan José García-Ripoll Phys. Rev. A 93, 043843 (2016)

Contact : olivier.buisson@neel.cnrs.fr