Dr. Matteo Caldara (Monash University), Quantum droplets of light in semiconductor microcavities
by
1/1-2 - Aula "C. Voci"
Dipartimento di Fisica e Astronomia - Edificio Marzolo
Quantum droplets are self-bound low-density configurations which may appear in ultracold gases when the attractive mean-field energy is balanced by the repulsive correction stemming from quantum fluctuations. Since their first predictions and experimental observations in dilute bosonic mixtures, the study of quantum droplets in cold-atomic settings has recently become a very
active research field. In this talk, I will show how a similar scenario arises also in solid-state systems, specifically atomically thin semiconductor layers. When these materials are embedded in an optical microcavity, exciton-polariton quasiparticles (polaritons) result from the strong coupling
between semiconductor excitons and cavity photon modes. Mixtures of two spin species of polaritons display an exceptional control of the interactions between the different components, which can be tuned to be either repulsive or attractive. Similarly to the case of quantum gases, the subtle balance between these competing interactions strongly enhances the role of quantum
fluctuations, leading to a regime where the polariton mixture arranges into a self-bound configuration that can be effectively regarded as a quantum droplet of light. These newly predicted droplets would unveil the elusive quantum nature of polariton quasiparticles and open a new promising avenue to achieve the long-sought quantum polaritonic regime, which is essential to
realize new quantum photonic applications in scalable semiconductors.
Prof. Luca Salasnich