Light-matter excitations in the ultra-strong coupling regime

Aji A. Anappara (1) , Simone de Liberato (2, 3) , Alessandro Tredicucci (1) , Cristiano Ciuti (2) , Giorgio Biasiol (4) , Lucia Sorba (1) , Fabio Beltram (1)

1 SNS - Scuola Normale Superiore di Pisa
2 MPQ (UMR_7162) - Laboratoire Matériaux et Phénomènes Quantiques
3 LPA - Laboratoire Pierre Aigrain
4 Laboratorio Nazionale TASC

In a microcavity, light-matter coupling is quantified by the vacuum Rabi frequency $\Omega_0$. When $\Omega_0$ is larger than radiative and non-radiative loss rates, the system eigenstates (polaritons) are linear superposition of photonic and electronic excitations, a condition actively investigated in diverse physical implementations. Recently, a quantum electrodynamic regime (ultra-strong coupling) was predicted when $\Omega_0$ becomes comparable to the transition frequency. Here we report unambiguous signatures of this regime in a quantum-well intersubband microcavity. Measuring the cavity-polariton dispersion in a room-temperature linear optical experiment, we directly observe the anti-resonant light-matter coupling and the photon-energy renormalization of the vacuum field.

Domaines: Physique Quantique [quant-ph]; Autre [cond-mat.other]

Aji A. Anappara, Simone de Liberato, Alessandro Tredicucci, Cristiano Ciuti, Giorgio Biasiol, et al.. Light-matter excitations in the ultra-strong coupling regime. 2008. ⟨hal-00315208v1⟩