Recently ultrafast time control of strong coupling (SC) regime has been achieved in intersubband polaritons . By exploiting an all-optical scheme, the dynamics of a coherent photon population, during sub-cycle switching-on of the SC, has been observed, opening a new domain of non-adiabatic light-matter interaction with unconventional quantum electrodynamics phenomena . Switching light-matter interaction allows to control qubit evolution with time resolutions significantly lower than decoherence times. However, in a such complex structure, the very basic phenomena related to this switching have not yet been completely understood and no complete all-optical coherent control has been reported.
In this seminar I will present our very recent results on the time-control of the SC between a single cascade three-level quantum emitter (QE) and a microcavity . This simpler model allows us to focus directly on the physics at the basis on the SC control and analyse deeply Vacuum Rabi Splitting switching, letting for future follow-ups a more refined realstic modeling. We find that, while the switch-on closely resembles the findings of Ref. , a more complex and intriguing behavior is observed when trying to switch-off the SC. Only specific arrival times of the control pulses succeed in switching-off, hence posing severe limitations on the SC full time-control. We found a nice explanation of the underlying physics in terms of quantum eraser phenomenology. Indeed, the induced entanglement between the cavity and the QE enables the latter to store the which-way information on photon paths, hence destroying coherence according to the quantum complementarity principle . The present study can be applied to an enormous variety of state-of-the-art experiments and setups ranging from atomic and circuit-QED systems to semiconductor intersubband polaritons and quantum dot in optical cavities, the present scheme may be almost directly applied.