Seminarium KMMF "Teoria Dwoistości"

The Bose polaron system consists of a Bose-Einstein condensateinteracting with one, or few, impurities. Similar polaron models ofparticles interacting with a bulk system appear in many forms incondensed matter physics, and play an important role, e.g., for theunderstanding of transport properties. The topic of my talk will be thederivation of an effective equation starting from a dilute system ofN>>1 interacting bosons and a single impurity. The effective descriptionis given by the Bogoliubov-Fröhlich Hamiltonian, which couples theimpurity linearly to Bogoliubov's excitation field in a similar way toother well-known polaron models. In the first part of the talk I willexplain the main results and the underlying heuristics. In the secondpart I will focus on the key points of the rigorous derivation inconnection with the renormalisation of the effective Hamiltonian. Thisis based on joint work with Arnaud Triay.