Interferometric Order Parameter for Excited-State Quantum Phase Transitions in Bose-Einstein Condensates

Year: 2021

Authors: Feldmann P., Klempt C., Smerzi A., Santos L., Gessner M.

Autors Affiliation: Institut fur Theoretische Physik, Leibniz Universitdt Hannover, AppelstraYAe 2, Hannover, 30167, Germany; Institut fur Quantenoptik, Leibniz Universitdt Hannover, Welfengarten 1, Hannover, 30167, Germany; Deutsches Zentrum f´r Luft- und Raumfahrt E.V. (DLR), Institut fur Satellitengeoddsie und Inertialsensorik, C/o Leibniz Universitdt Hannover, DLR-SI, CallinstraYAe 36, Hannover, 30167, Germany; Qstar, INO-CNR, Lens, Largo Enrico Fermi 2, Firenze, 50125, Italy; Laboratoire Kastler Brossel, ENS-University Psl, Cnrs, Sorbonne University, Collige de France, 24 Rue Lhomond, Paris, 75005, France

Abstract: Excited-state quantum phase transitions extend the notion of quantum phase transitions beyond the ground state. They are characterized by closing energy gaps amid the spectrum. Identifying order parameters for excited-state quantum phase transitions poses, however, a major challenge. We introduce a topological order parameter that distinguishes excited-state phases in a large class of mean-field models and can be accessed by interferometry in current experiments with spinor Bose-Einstein condensates. Our work opens a way for the experimental characterization of excited-state quantum phases in atomic many-body systems.


Volume: 126 (23)      Pages from: 230602-1  to: 230602-6

More Information: We thank Dmytro Bondarenko, Pavel Cejnar, Ignacio Cirac, and Reinhard Werner for valuable discussions. We acknowledge support by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under the SFB 1227 “DQ-mat”, project A02, and under Germany´s Excellence Strategy-EXC-2123 QuantumFrontiers-390837967, and by the LabEx ENSICFP: ANR-10-LABX-0010/ANR-10-IDEX-0001-02 PSL*.
KeyWords: monodromy; dynamics; systems
DOI: 10.1103/PhysRevLett.126.230602