2015/02/28 by Richard Schmidt, Mikhail Lemeshko · 1 citation
Physics and Astronomy · #cond-mat.quant-gas #physics.atm-clus #physics.atom-ph #physics.chem-ph #quant-ph
paper · pdf · doi:10.1103/physrevlett.114.203001
published as Phys. Rev. Lett. 114, 203001 (2015) · 5 pages, 2 figures; revised version, supplementary added
arxiv created 2015/04/01 · arxiv updated 2015/05/27
We develop a microscopic theory describing a quantum impurity whose rotational degree of freedom is coupled to a many-particle bath. We approach the problem by introducing the concept of an 'angulon' - a quantum rotor dressed by a quantum field - and reveal its quasiparticle properties using a combination of variational and diagrammatic techniques. Our theory predicts renormalisation of the impurity rotational structure, such as observed in experiments with molecules in superfluid helium droplets, in terms of a rotational Lamb shift induced by the many-particle environment. Furthermore, we discover a rich many-body-induced fine structure, emerging in rotational spectra due to a redistribution of angular momentum within the quantum many-body system.