



01682nas a2200193   4500008004100000245006100041210006100102260001500163300001100178490000700189520113200196100002101328700002101349700001301370700002501383700002101408700002301429856003601452       2016                        eng d00aCollective phases of strongly interacting cavity photons0 aCollective phases of strongly interacting cavity photons  c2016/09/01  a0338010 v943 a<p>We study a coupled array of coherently driven photonic cavities, which maps onto a driven-dissipative XY spin-12 model with ferromagnetic couplings in the limit of strong optical nonlinearities. Using a site-decoupled mean-field approximation, we identify steady state phases with canted antiferromagnetic order, in addition to limit cycle phases, where oscillatory dynamics persist indefinitely. We also identify collective bistable phases, where the system supports two steady states among spatially uniform, antiferromagnetic, and limit cycle phases. We compare these mean-field results to exact quantum trajectories simulations for finite one-dimensional arrays. The exact results exhibit short-range antiferromagnetic order for parameters that have significant overlap with the mean-field phase diagram. In the mean-field bistable regime, the exact quantum dynamics exhibits real-time collective switching between macroscopically distinguishable states. We present a clear physical picture for this dynamics, and establish a simple relationship between the switching times and properties of the quantum Liouvillian.</p>1 aWilson, Ryan, M.1 aMahmud, Khan, W.1 aHu, Anzi1 aGorshkov, Alexey, V.1 aHafezi, Mohammad1 aFoss-Feig, Michael  uhttp://arxiv.org/abs/1601.0685701814nas a2200205   4500008004100000245007600041210006900117260001500186300001100201490000700212520120100219100001901420700002701439700001301466700002301479700002101502700002401523700002501547856003601572       2016                        eng d00aKaleidoscope of quantum phases in a long-range interacting spin-1 chain0 aKaleidoscope of quantum phases in a longrange interacting spin1   c2016/05/11  a2051150 v933 aMotivated by recent trapped-ion quantum simulation experiments, we carry out a comprehensive study of the phase diagram of a spin-1 chain with XXZ-type interactions that decay as 1/rα, using a combination of finite and infinite-size DMRG calculations, spin-wave analysis, and field theory. In the absence of long-range interactions, varying the spin-coupling anisotropy leads to four distinct phases: a ferromagnetic Ising phase, a disordered XY phase, a topological Haldane phase, and an antiferromagnetic Ising phase. If long-range interactions are antiferromagnetic and thus frustrated, we find primarily a quantitative change of the phase boundaries. On the other hand, ferromagnetic (non-frustrated) long-range interactions qualitatively impact the entire phase diagram. Importantly, for α≲3, long-range interactions destroy the Haldane phase, break the conformal symmetry of the XY phase, give rise to a new phase that spontaneously breaks a U(1) continuous symmetry, and introduce an exotic tricritical point with no direct parallel in short-range interacting spin chains. We show that the main signatures of all five phases found could be observed experimentally in the near future.
1 aGong, Zhe-Xuan1 aMaghrebi, Mohammad, F.1 aHu, Anzi1 aFoss-Feig, Michael1 aRicherme, Philip1 aMonroe, Christopher1 aGorshkov, Alexey, V.  uhttp://arxiv.org/abs/1510.0210801535nas a2200193   4500008004100000245005200041210005100093260001500144300001100159490000700170520099900177100001901176700002701195700001301222700002201235700002301257700002501280856003601305       2016                        eng d00aTopological phases with long-range interactions0 aTopological phases with longrange interactions  c2016/01/08  a0411020 v933 a  Topological phases of matter are primarily studied in quantum many-body
systems with short-range interactions. Whether various topological phases can
survive in the presence of long-range interactions, however, is largely
unknown. Here we show that a paradigmatic example of a symmetry-protected
topological phase, the Haldane phase of an antiferromagnetic spin-1 chain,
surprisingly remains intact in the presence of arbitrarily slowly decaying
power-law interactions. The influence of long-range interactions on the
topological order is largely quantitative, and we expect similar results for
more general systems. Our conclusions are based on large-scale
matrix-product-state simulations and two complementary effective-field-theory
calculations. The striking agreement between the numerical and analytical
results rules out finite-size effects. The topological phase considered here
should be experimentally observable in a recently developed trapped-ion quantum
simulator.
1 aGong, Zhe-Xuan1 aMaghrebi, Mohammad, F.1 aHu, Anzi1 aWall, Michael, L.1 aFoss-Feig, Michael1 aGorshkov, Alexey, V.  uhttp://arxiv.org/abs/1505.0314601241nas a2200181   4500008004100000245007500041210006900116260001500185490000700200520070200207100001300909700001500922700001900937700002000956700002300976700002300999856003701022       2011                        eng d00aDetecting paired and counterflow superfluidity via dipole oscillations0 aDetecting paired and counterflow superfluidity via dipole oscill  c2011/10/270 v843 a  We suggest an experimentally feasible procedure to observe paired and
counterflow superfluidity in ultra-cold atom systems. We study the time
evolution of one-dimensional mixtures of bosonic atoms in an optical lattice
following an abrupt displacement of an additional weak confining potential. We
find that the dynamic responses of the paired superfluid phase for attractive
inter-species interactions and the counterflow superfluid phase for repulsive
interactions are qualitatively distinct and reflect the quasi long-range order
that characterizes these states. These findings suggest a clear experimental
procedure to detect these phases, and give an intuitive insight into their
dynamics.
1 aHu, Anzi1 aMathey, L.1 aTiesinga, Eite1 aDanshita, Ippei1 aWilliams, Carl, J.1 aClark, Charles, W.  uhttp://arxiv.org/abs/1103.3513v301378nas a2200157   4500008004100000245007600041210006900117260001300186490000700199520090300206100001301109700001501122700002301137700002301160856003701183       2010                        eng d00aNoise correlations of one-dimensional Bose mixtures in optical lattices0 aNoise correlations of onedimensional Bose mixtures in optical la  c2010/6/20 v813 a  We study the noise correlations of one-dimensional binary Bose mixtures, as a
probe of their quantum phases. In previous work, we found a rich structure of
many-body phases in such mixtures, such as paired and counterflow
superfluidity. Here we investigate the signature of these phases in the noise
correlations of the atomic cloud after time-of-flight expansion, using both
Luttinger liquid theory and the time-evolving block decimation (TEBD) method.
We find that paired and counterflow superfluidity exhibit distinctive features
in the noise spectra. We treat both extended and inhomogeneous systems, and our
numerical work shows that the essential physics of the extended systems is
present in the trapped-atom systems of current experimental interest. For
paired and counterflow superfluid phases, we suggest methods for extracting
Luttinger parameters from noise correlation spectroscopy.
1 aHu, Anzi1 aMathey, L.1 aWilliams, Carl, J.1 aClark, Charles, W.  uhttp://arxiv.org/abs/1002.4918v201819nas a2200181   4500008004100000245009700041210006900138260001400207490000700221520125900228100001301487700001501500700002001515700001901535700002301554700002301577856003701600       2009                        eng d00aCounterflow and paired superfluidity in one-dimensional Bose mixtures in  optical lattices
0 aCounterflow and paired superfluidity in onedimensional Bose mixt  c2009/8/240 v803 a  We study the quantum phases of mixtures of ultra-cold bosonic atoms held in
an optical lattice that confines motion or hopping to one spatial dimension.
The phases are found by using Tomonaga-Luttinger liquid theory as well as the
numerical method of time evolving block decimation (TEBD). We consider a binary
mixture with repulsive intra-species interactions, and either repulsive or
attractive inter-species interaction. For a homogeneous system, we find paired-
and counterflow-superfluid phases at different filling and hopping energies. We
also predict parameter regions in which these types of superfluid order coexist
with charge density wave order. We show that the Tomonaga-Luttinger liquid
theory and TEBD qualitatively agree on the location of the phase boundary to
superfluidity. We then describe how these phases are modified and can be
detected when an additional harmonic trap is present. In particular, we show
how experimentally measurable quantities, such as time-of-flight images and the
structure factor, can be used to distinguish the quantum phases. Finally, we
suggest applying a Feshbach ramp to detect the paired superfluid state, and a
$\pi/2$ pulse followed by Bragg spectroscopy to detect the counterflow
superfluid phase.
1 aHu, Anzi1 aMathey, L.1 aDanshita, Ippei1 aTiesinga, Eite1 aWilliams, Carl, J.1 aClark, Charles, W.  uhttp://arxiv.org/abs/0906.2150v1