Manipulating multilevel coherence in architectures of artificial atoms is a key issue for achievements in both fundamental and applied physics. Fabrication techniques have recently allowed to produce ultra-strong coupling (USC) between light and matter, a regime where previously unexplored non-perturbative phenomena emerge . While experiments so far provided spectroscopic evidence of USC, we propose the dynamical detection of atom-cavity USC [2,3]. Indeed USC opens a new channel for photon-pair production, whose detection is a smoking gun its existence in Nature. We show how to coherently amplify this channel to ~100% efficiency by advanced control similar to STIRAP in atomic physics. To this end we propose to operate a three level atom, where a selected transition is coupled in the USC regime to a cavity. Unambiguous detection of USC poses strong design constraints on quantum hardware, the requirements being uniquely met by superconducting artificial atoms (persistent current qubits), driven in the the Vee configuration . Besides its fundamental importance, dynamical detection of USC in state of the art systems would be a benchmark for quantum control in distributed networks, exploiting new ideas of adiabatic protocols in this regime[2,3].
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