Organic charged polaritons in the ultrastrong coupling regime

We embedded an all-hydrocarbon-based carbocation in a metallic microcavity that was tuned to resonance with electronic transition of the carbocation. The measured Rabi splitting 41% excitation energy, putting system well into ultrastrong coupling regime. Importantly, due intrinsic charge on carbocation, polaritons form carry significant fraction $0.55 e_0$ and large charge-to-mass ratio ($\sim 2400 e_0 / m_0$). Moreover, ground state ultrastrongly coupled is calculated about one percent elementary charge, implying potentially enhanced transport across molecules. These unique properties our system, together its convenient preparation, provide practical platform study charged