APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013;
Baltimore, Maryland
Session B4: Invited Session: Cold Atoms on Higher Orbital Bands
11:15 AM–2:15 PM,
Monday, March 18, 2013
Room: Ballroom IV
Sponsoring
Units:
DAMOP DCMP
Chair: Erhai Zhao, George Mason University
Abstract ID: BAPS.2013.MAR.B4.3
Abstract: B4.00003 : Higher orbital physics and artificial gauge fields with ultracold quantum gases
12:27 PM–1:03 PM
Preview Abstract
Abstract
Author:
Klaus Sengstock
(Universitaet Hamburg, ILP, Luruper Chaussee 149, 22761 Hamburg)
Recently the physics of quantum gases in higher orbitals attracted a lot of
attention, theoretically and experimentally. We report on studies of a new
type of superfluid described by a complex order parameter, resulting from an
interaction-induced hybridization of the two lowest orbitals for a binary
spin-mixture. As a main result we observe a quantum phase transition between
the normal superfluid and this unconventional superfluid phase, where the
local phase angle of the complex order parameter is continuously twisted
between neighboring lattice sites [1].
In addition we discuss new experimental work on the creation of artificial
gauge potentials for neutral atoms in 1D and 2D lattices, which do not rely
on the internal structure of the atoms. Via a time-dependent driving of the
optical lattice we have full control over amplitude and phase of the complex
valued hopping parameters.
In a 2D triangular lattice, we demonstrate the realization of gauge
invariant staggered fluxes [2]. Our system consists of an array of tubes
filled with bosonic atoms having a well-defined local phase. The phase
distribution obtained in presence of large amplitude staggered fluxes --
where frustration plays a key role - obeys two fundamental symmetries, the
discrete Ising symmetry (Z2) and a continuous global phase symmetry (U(1)).
Via the full control of the staggered gauge fields [3], we are able to break
the Ising symmetry on purpose which means lifting the degeneracy of the two
possible Ising states, in analogy to a longitudinal homogenous magnetic
field in the standard Ising-Spin model. The measurements reveal ``textbook
like'' magnetization curves with the well known dependence on both, the
external magnetic field and the temperature. We observe a thermally driven
phase transition from an ordered Ising (ferromagnetic) to an unordered
(paramagnetic) state.
Future directions to combine orbital physics and gauge fields will be
discussed.\\[4pt]
[1] Soltan-Panahi et al., Nature Physics 8, 75 (2012)\\[0pt]
[2] Struck et al., Science 333, 996 (2011)\\[0pt]
[3] Struck et al., PRL 108, 225304 (2012)
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2013.MAR.B4.3