This week we have the pleasure to receive Marcelo F. Santos (UFRJ) as a speaker in our series QM Talks@CBPF. Marcelo and co-authors have recently put in the arXiv an intriguing paper: Photonic Counterparts of Cooper Pairs. This article, already accepted for publication in Physical Review Letters, attracted quite some attention (see here the Nature News feature on the article) for proposing that photons can interact inside a medium in a way very similar to that of electrons in a superconducting material, forming the so-called Cooper pairs. Got interested?! Then do not miss Marcelo’s talk. The info follows:
Title: Photonic Cooper pairs
Speaker: Marcelo F. Santos (UFRJ)
Coordinates: room 601C, CBPF. 08.11, 16h00
Abstract: Photons are the elementary particles of light. Contrary to most particles, photons do not interact directly with each other in vacuum. However, when propagating in a material, e.g. water, photon pairs may interact through the medium. In the Raman effect, for example, it is possible that a photon creates or absorbs a vibrational excitation of the material. In this work, we demonstrate theoretically and experimentally that photon pairs may interact via a virtual vibration, meaning that the energy exchanged in the process does not correspond to a quantum of vibrational energy. The same process occurs in a metal at very low temperatures, where virtual vibrations of the medium create an effective attractive interaction between electrons, forming the so-called Cooper pairs. This phenomenon changes a normal metal into a superconductor – a zero-resistance state. We have shown theoretically and experimentally the analogue of this phenomenon with light, namely an effective photon-photon interaction mediated by a virtual vibration, i.e, a photonic Cooper pair. An important next step is to test how far the analogy with superconductivity extends.