



01174nas a2200109   4500008004100000245007300041210006900114520080600183100001900989700001901008856003701027       2018                        eng d00aA semiclassical theory of phase-space dynamics of interacting bosons0 asemiclassical theory of phasespace dynamics of interacting boson3 a<p>We study the phase-space representation of dynamics of bosons in the semiclassical regime where the occupation number of the modes is large. To this end, we employ the van Vleck-Gutzwiller propagator to obtain an approximation for the Green&#39;s function of the Wigner distribution. The semiclassical analysis incorporates interference of classical paths and reduces to the truncated Wigner approximation (TWA) when the interference is ignored. Furthermore, we identify the Ehrenfest time after which the TWA fails. As a case study, we consider a single-mode quantum nonlinear oscillator, which displays collapse and revival of observables. We analytically show that the interference of classical paths leads to revivals, an effect that is not reproduced by the TWA or a perturbative analysis.</p>1 aMathew, Ranchu1 aTiesinga, Eite  uhttps://arxiv.org/abs/1803.0512201747nas a2200157   4500008004100000245008800041210006900129260001500198300001100213490000700224520127000231100001801501700001501519700001901534856003601553       2016                        eng d00aSudden-quench dynamics of Bardeen-Cooper-Schrieffer states in deep optical lattices0 aSuddenquench dynamics of BardeenCooperSchrieffer states in deep   c2016/08/05  a0236070 v943 a<p>We determine the exact time evolution of an initial Bardeen-Cooper-Schrieffer (BCS) state of ultra-cold atoms in a hexagonal optical lattice. The dynamical evolution is triggered by ramping the lattice potential up, such that the interaction strength Uf is much larger than the hopping amplitude Jf. The quench initiates collective oscillations with frequency |Uf|/(2π) in the momentum occupation numbers and imprints an oscillating phase with the same frequency on the order parameter Δ. The latter is not reproduced by treating the time evolution in mean-field theory. The momentum density-density or noise correlation functions oscillate at frequency |Uf|/2π as well as its second harmonic. For a very deep lattice, with negligible tunneling energy, the oscillations of momentum occupation numbers are undamped. Non-zero tunneling after the quench leads to dephasing of the different momentum modes and a subsequent damping of the oscillations. This occurs even for a finite-temperature initial BCS state, but not for a non-interacting Fermi gas. We therefore propose to use this dephasing to detect a BCS state. Finally, we predict that the noise correlation functions in a honeycomb lattice will develop strong anti-correlations near the Dirac point.</p>1 aNuske, Marlon1 aMathey, L.1 aTiesinga, Eite  uhttp://arxiv.org/abs/1602.0097901945nas a2200205   4500008004100000245007600041210006900117260001500186300001100201490000700212520133700219100001901556700001901575700001901594700002401613700002701637700001801664700001901682856003801701       2015                        eng d00aSelf-heterodyne detection of the {\it in-situ} phase of an atomic-SQUID0 aSelfheterodyne detection of the it insitu phase of an atomicSQUI  c2015/09/03  a0336020 v923 a  We present theoretical and experimental analysis of an interferometric
measurement of the {\it in-situ} phase drop across and current flow through a
rotating barrier in a toroidal Bose-Einstein condensate (BEC). This experiment
is the atomic analog of the rf-superconducting quantum interference device
(SQUID). The phase drop is extracted from a spiral-shaped density profile
created by the spatial interference of the expanding toroidal BEC and a
reference BEC after release from all trapping potentials. We characterize the
interferometer when it contains a single particle, which is initially in a
coherent superposition of a torus and reference state, as well as when it
contains a many-body state in the mean-field approximation. The single-particle
picture is sufficient to explain the origin of the spirals, to relate the
phase-drop across the barrier to the geometry of a spiral, and to bound the
expansion times for which the {\it in-situ} phase can be accurately determined.
Mean-field estimates and numerical simulations show that the inter-atomic
interactions shorten the expansion time scales compared to the single-particle
case. Finally, we compare the mean-field simulations with our experimental data
and confirm that the interferometer indeed accurately measures the {\it
in-situ} phase drop.
1 aMathew, Ranchu1 aKumar, Avinash1 aEckel, Stephen1 aJendrzejewski, Fred1 aCampbell, Gretchen, K.1 aEdwards, Mark1 aTiesinga, Eite  uhttp://arxiv.org/abs/1506.09149v201304nas a2200169   4500008004100000245009000041210006900131260001400200490000700214520080200221100001501023700001901038700001601057700001201073700001201085856003701097       2014                        eng d00aSpin-orbit-coupled topological Fulde-Ferrell states of fermions in a  harmonic trap
0 aSpinorbitcoupled topological FuldeFerrell states of fermions in   c2014/11/70 v903 a  Motivated by recent experimental breakthroughs in generating spin-orbit
coupling in ultracold Fermi gases using Raman laser beams, we present a
systematic study of spin-orbit-coupled Fermi gases confined in a
quasi-one-dimensional trap in the presence of an in-plane Zeeman field (which
can be realized using a finite two-photon Raman detuning). We find that a
topological Fulde-Ferrell state will emerge, featuring finite-momentum Cooper
pairing and zero-energy Majorana excitations localized near the edge of the
trap based on the self-consistent Bogoliubov-de Genes (BdG) equations. We find
analytically the wavefunctions of the Majorana modes. Finally using the
time-dependent BdG we show how the finite-momentum pairing field manifests
itself in the expansion dynamics of the atomic cloud.
1 aJiang, Lei1 aTiesinga, Eite1 aLiu, Xia-Ji1 aHu, Hui1 aPu, Han  uhttp://arxiv.org/abs/1404.6211v101731nas a2200145   4500008004100000245007000041210006900111260001300180490000700193520128300200100002401483700002201507700001901529856003701548       2013                        eng d00aSoliton dynamics of an atomic spinor condensate on a Ring Lattice0 aSoliton dynamics of an atomic spinor condensate on a Ring Lattic  c2013/3/60 v873 a  We study the dynamics of macroscopically-coherent matter waves of an
ultra-cold atomic spin-one or spinor condensate on a ring lattice of six sites
and demonstrate a novel type of spatio-temporal internal Josephson effect.
Using a discrete solitary mode of uncoupled spin components as an initial
condition, the time evolution of this many-body system is found to be
characterized by two dominant frequencies leading to quasiperiodic dynamics at
various sites. The dynamics of spatially-averaged and spin-averaged degrees of
freedom, however, is periodic enabling an unique identification of the two
frequencies. By increasing the spin-dependent atom-atom interaction strength we
observe a resonance state, where the ratio of the two frequencies is a
characteristic integer multiple and the spin-and-spatial degrees of freedom
oscillate in "unison". Crucially, this resonant state is found to signal the
onset to chaotic dynamics characterized by a broad band spectrum. In a
ferromagnetic spinor condensate with attractive spin-dependent interactions,
the resonance is accompanied by a transition from oscillatory- to
rotational-type dynamics as the time evolution of the relative phase of the
matter wave of the individual spin projections changes from bounded to
unbounded.
1 aSatija, Indubala, I1 aPando, Carlos, L.1 aTiesinga, Eite  uhttp://arxiv.org/abs/1301.5851v101428nas a2200193   4500008004100000245006800041210006700109260001300176490000800189520085100197100002401048700002501072700002201097700002201119700001801141700001901159700001901178856003701197       2013                        eng d00aSpinor dynamics in an antiferromagnetic spin-1 thermal Bose gas0 aSpinor dynamics in an antiferromagnetic spin1 thermal Bose gas  c2013/7/90 v1113 a  We present experimental observations of coherent spin-population oscillations
in a cold thermal, Bose gas of spin-1 sodium-23 atoms. The population
oscillations in a multi-spatial-mode thermal gas have the same behavior as
those observed in a single-spatial-mode antiferromagnetic spinor Bose Einstein
condensate. We demonstrate this by showing that the two situations are
described by the same dynamical equations, with a factor of two change in the
spin-dependent interaction coefficient, which results from the change to
particles with distinguishable momentum states in the thermal gas. We compare
this theory to the measured spin population evolution after times up to a few
hundreds of ms, finding quantitative agreement with the amplitude and period.
We also measure the damping time of the oscillations as a function of magnetic
field.
1 aPechkis, Hyewon, K.1 aWrubel, Jonathan, P.1 aSchwettmann, Arne1 aGriffin, Paul, F.1 aBarnett, Ryan1 aTiesinga, Eite1 aLett, Paul, D.  uhttp://arxiv.org/abs/1306.4255v101279nas a2200181   4500008004100000245009100041210006900132260001400201490000700215520071200222100002000934700002000954700001900974700002500993700002301018700001901041856003701060       2011                        eng d00aSpatial separation in a thermal mixture of ultracold $^{174}$Yb and  $^{87}$Rb atoms
0 aSpatial separation in a thermal mixture of ultracold 174 Yb and   c2011/4/210 v833 a  We report on the observation of unusually strong interactions in a thermal
mixture of ultracold atoms which cause a significant modification of the
spatial distribution. A mixture of $^{87}$Rb and $^{174}$Yb with a temperature
of a few $\mu$K is prepared in a hybrid trap consisting of a bichromatic
optical potential superimposed on a magnetic trap. For suitable trap parameters
and temperatures, a spatial separation of the two species is observed. We infer
that the separation is driven by a large interaction strength between
$^{174}$Yb and $^{87}$Rb accompanied by a large three-body recombination rate.
Based on this assumption we have developed a diffusion model which reproduces
our observations.
1 aBaumer, Florian1 aMünchow, Frank1 aGörlitz, Axel1 aMaxwell, Stephen, E.1 aJulienne, Paul, S.1 aTiesinga, Eite  uhttp://arxiv.org/abs/1104.1722v101304nas a2200145   4500008004100000245006900041210006900110260001300179490000700192520086300199100001801062700002201080700001901102856003701121       2011                        eng d00aSuperradiance of cold atoms coupled to a superconducting circuit0 aSuperradiance of cold atoms coupled to a superconducting circuit  c2011/6/60 v833 a  We investigate superradiance of an ensemble of atoms coupled to an integrated
superconducting LC-circuit. Particular attention is paid to the effect of
inhomogeneous coupling constants. Combining perturbation theory in the
inhomogeneity and numerical simulations we show that inhomogeneous coupling
constants can significantly affect the superradiant relaxation process.
Incomplete relaxation terminating in "dark states" can occur, from which the
only escape is through individual spontaneous emission on a much longer time
scale. The relaxation dynamics can be significantly accelerated or retarded,
depending on the distribution of the coupling constants. On the technical side,
we also generalize the previously known propagator of superradiance for
identical couplings in the completely symmetric sector to the full
exponentially large Hilbert space.
1 aBraun, Daniel1 aHoffman, Jonathan1 aTiesinga, Eite  uhttp://arxiv.org/abs/1101.5300v101196nas a2200217   4500008004100000245005900041210005800100260001500158490000700173520059700180100001100777700001200788700002300800700001800823700001700841700001900858700001700877700002100894700001900915856004400934       2005                        eng d00aSodium Bose-Einstein Condensates in an Optical Lattice0 aSodium BoseEinstein Condensates in an Optical Lattice  c2005/10/100 v723 a  The phase transition from a superfluid to a Mott insulator has been observed
in a $^{23}$Na Bose-Einstein condensate. A dye laser detuned $\approx 5$nm red
of the Na $3^2$S$ \to 3^2$P$_{1/2}$ transition was used to form the three
dimensional optical lattice. The heating effects of the small detuning as well
as the three-body decay processes constrained the timescale of the experiment.
Certain lattice detunings were found to induce a large loss of atoms. These
loss features were shown to be due to photoassociation of atoms to vibrational
levels in the Na$_2$ $(1) ^3\Sigma_g^+$ state.
1 aXu, K.1 aLiu, Y.1 aAbo-Shaeer, J., R.1 aMukaiyama, T.1 aChin, J., K.1 aMiller, D., E.1 aKetterle, W.1 aJones, Kevin, M.1 aTiesinga, Eite  uhttp://arxiv.org/abs/cond-mat/0507288v101059nas a2200145   4500008004100000245006200041210006100103260001400164490000700178520062000185100002200805700001900827700002300846856004400869       2005                        eng d00aSpontaneous dissociation of long-range Feshbach molecules0 aSpontaneous dissociation of longrange Feshbach molecules  c2005/1/180 v943 a  We study the spontaneous dissociation of diatomic molecules produced in cold
atomic gases via magnetically tunable Feshbach resonances. We provide a
universal formula for the lifetime of these molecules that relates their decay
to the scattering length and the loss rate constant for inelastic spin
relaxation. Our universal treatment as well as our exact coupled channels
calculations for $^{85}$Rb dimers predict a suppression of the decay over
several orders of magnitude when the scattering length is increased. Our
predictions are in good agreement with recent measurements of the lifetime of
$^{85}$Rb$_2$.
1 aKoehler, Thorsten1 aTiesinga, Eite1 aJulienne, Paul, S.  uhttp://arxiv.org/abs/cond-mat/0408387v2