"A Free Space Self-Ordered Atom-Photon Crystal" Event as iCalendar
13 February 2017
2 - 3pm
Speaker: H. Ritsch, Institut für Theoretische Physik, Universität Innsbruck, Austria
Title: "A Free Space Self-Ordered Atom-Photon Crystal"
dispersive interaction of a cold gaseous medium with electromagnetic waves
involves an exchange of energy and momentum leads to a wealth of intriguing
nonlinear dynamical phenomena. A prominent example is self-ordering, whereby
the particles spontaneously form stationary periodic structures, simultaneously
maximising Bragg scattering and minimizing their potential energy. This has
been experimentally observed with thermal gases and more recently also with
Bose-Einstein condensates (BECs) inside optical resonators. The latter selects
a discrete set of electromagnetic modes so that self-ordering leads to discrete
As a new regime we study steady-state self-ordering with a driven BEC in a free-space configuration, where no pre-selected wave vectors are imposed by the mirror boundary conditions. Hence self-ordering amounts to a crystallization breaking a continuous symmetry and showing an intrinsic length scale. In the self-ordered phase both matter and light crystallize: the BEC into a supersolid and the light field into an optical standing wave pattern. As a decisive signature of crystallization the close to infinite range atomic interactions generate a gapped acoustic phonon branch.