### Session B4: Invited Session: Cold Atoms on Higher Orbital Bands

11:15 AM–2:15 PM, Monday, March 18, 2013
Room: Ballroom IV

Chair: Erhai Zhao, George Mason University

Abstract ID: BAPS.2013.MAR.B4.4

### Abstract: B4.00004 : Orbital physics in one dimensional optical lattices

1:03 PM–1:39 PM

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#### Author:

Xiaopeng Li
(University of Pittsburgh)

We explore orbital physics of fermions and bosons in one dimensional optical lattices. In a system of one dimensional $p$-orbital bosons, various phases, including anti-ferro-orbital Mott, anti-ferro-orbital superfluid and para-orbital superfluid, have been found. Signatures of phase transitions, in particular time-reversal symmetry breaking, in time-of-flight image are predicted. A fermionic ladder system composed of $s$ and $p$ orbitals is proposed, and we find a topological state featuring fractional defects. An equivalent of spin-orbit coupling naturally arises, not requiring artificial gauge field, in this quantum orbital ladder when the $s$ and $p$ orbital states are identified as a pseudo-spin 1/2. Extending this ladder system to two dimensions we find a flat-band protected by parity. The flat-band makes it plausible to study strongly correlated physics in this system. We also discuss the connection of this fermionic ladder to frustrated $\pi$ flux models and spin-orbital coupled fermions.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2013.MAR.B4.4