Martin Weitz

Integer and fractional quantum Hall states, as first have been realized with electrons in strong magnetic fields, have a nontrivial topological order. Atoms are electrically neutral, but magnetic fields here can be emulated by phase imprinting with far detuned Raman beams. This research project aims to realize strong synthetic magnetic fields for cold atomic erbium atoms. Our main goal is to explore many-body fractional quantum Hall physics with the well-controlled neutral atom system. While the in AMO physics more commonly used alkali atomic species have an L=0 electronic ground state, in the case of the erbium atomic species used in our experiment the orbital angular momentum of the electronic ground state with L=5 is non-vanishing. This allows for state-dependent Raman manipulation with large detunings of the driving optical fields and the imprinting of strong synthetic magnetic fields with corresponding long coherence times. In so far achieved work, we have observed evidence for integer quantum Hall physics with the atomic erbium system. In the next funding period, we will study finite temperature effects of our topological system. We will also work to achieve stronger synthetic fields to move to fractional quantum Hall physics. Evidence for the presence of a bosonic many-body Laughlin state will be obtained from (i) the observation of collapse and revival of an array of two-dimensional atomic microclouds subject to the strong synthetic field, (ii) the observation of the second order coherence of atoms, and (iii) dissipative detection of the topological state by means of circular dichroism.