Orbital superfluidity in the $P$-band of a bipartite optical square lattice
By G. Wirth, M. Olschlager, A. Hemmerich. 2010
160 citations recorded by the source corpus.
The successful emulation of the Hubbard model in optical lattices has stimulated world wide efforts to extend their scope to also capture more complex, incompletely understood scenarios of many-body physics. Unfortunately, for bosons, Feynmans fundamental "no-node" theorem under very general circumstances predicts a positive definite ground state wave function with limited relevance for many-body systems of interest. A promising way around Feynmans statement is to consider higher bands in optical lattices with more than one dimension, where the orbital degree of freedom with its intrinsic anisotropy due to multiple orbital orientations gives rise to a structural diversity, highly relevant, for example, in the area of strongly correlated electronic matter. In homogeneous two-dimensional optical lattices, lifetimes of excited bands on the order of a hundred milliseconds are possible but the tunneling dynamics appears not to support cross-dimensional coherence. Here we report the first observation of a superfluid in the $P$-band of a bipartite optical square lattice with $S$-orbits and $P$-orbits arranged in a chequerboard pattern. This permits us to establish full cross-dimensional coherence with a life-time of several ten milliseconds. Depending on a small adjustable anisotropy of the lattice, we can realize real-valued striped superfluid order parameters with different orientations $P_x \pm P_y$ or a complex-valued $P_x \pm i P_y$ order parameter, which breaks time reversal symmetry and resembles the $\pi$-flux model proposed in the context of high temperature superconductors. Our experiment opens up the realms of orbital superfluids to investigations with optical lattice models.
Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics
View Paper: https://www.semanticscholar.org/paper/7d30e09b7d2e0b407b6a4aa3a6a623a6899c1a77
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In Atomic and Molecular Physics, and Optics
Citations in the corpus
- Quantum phase transition to unconventional multi-orbital superfluidity in optical lattices (2011, background): “So far, orbital superfluidity has been observed only in excited states with limited lifetime”
- Topological characterizations of an extended Su–Schrieffer–Heeger model (2019, unknown): “[17] Wirth, G.”
- Topological semimetal in a fermionic optical lattice (2010, background): “The recent implementation of orbital degrees of freedom in chequerboar”
- Dynamical d -wave condensation of exciton–polaritons in a two-dimensional square-lattice potential (2011, methodology): “Recently, a p -orbital condensate using ultracold atoms in an optical lattice has been prepare”