Orbital Many-Body Dynamics of Bosons in the Second Bloch Band of an Optical Lattice

We explore Josephson-like dynamics of a Bose-Einstein condensate of rubidium atoms in the second Bloch band of an optical square lattice providing a double well structure with two inequivalent, degenerate energy minima. This oscillation is a direct signature of the orbital changing collisions predic...

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Veröffentlicht in:Physical review letters 2021-05, Vol.126 (20), p.1-200402, Article 200402
Hauptverfasser: Vargas, J, Nuske, M, Eichberger, R, Hippler, C, Mathey, L, Hemmerich, A
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Sprache:eng
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Zusammenfassung:We explore Josephson-like dynamics of a Bose-Einstein condensate of rubidium atoms in the second Bloch band of an optical square lattice providing a double well structure with two inequivalent, degenerate energy minima. This oscillation is a direct signature of the orbital changing collisions predicted to arise in this system in addition to the conventional on-site collisions. The observed oscillation frequency scales with the relative strength of these collisional interactions, which can be readily tuned via a distortion of the unit cell. The observations are compared to a quantum model of two single-particle modes and to a semiclassical multiband tight-binding simulation of 12 × 12 tubular sites of the lattice. Both models reproduce the observed oscillatory dynamics and show the correct dependence of the oscillation frequency on the ratio between the strengths of the on-site and orbital changing collision processes.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.126.200402