Liquid quantum droplets of ultracold magnetic atoms

Abstract

The simultaneous presence of two competing inter-particle interactions can\nlead to the emergence of new phenomena in a many-body system. Among others,\nsuch effects are expected in dipolar Bose-Einstein condensates, subject to\ndipole-dipole interaction and short-range repulsion. Magnetic quantum gases and\nin particular Dysprosium gases, offering a comparable short-range contact and a\nlong-range dipolar interaction energy, remarkably exhibit such emergent\nphenomena. In addition an effective cancellation of mean-field effects of the\ntwo interactions results in a pronounced importance of quantum-mechanical\nbeyond mean-field effects. For a weakly-dominant dipolar interaction the\nstriking consequence is the existence of a new state of matter equilibrated by\nthe balance between weak mean-field attraction and beyond mean-field repulsion.\nThough exemplified here in the case of dipolar Bose gases, this state of matter\nshould appear also with other microscopic interactions types, provided a\ncompetition results in an effective cancellation of the total mean-field. The\nmacroscopic state takes the form of so-called quantum droplets. We present the\neffects of a long-range dipolar interaction between these droplets.\n