@article {2585,
title = {Collisions of room-temperature helium with ultracold lithium and the van der Waals bound state of HeLi},
journal = {Phys. Rev. A },
volume = {101},
year = {2020},
month = {1/6/2020},
abstract = {
We have computed the thermally averaged total, elastic rate coefficient for the collision of a room-temperature helium atom with an ultracold lithium atom. This rate coefficient has been computed as part of the characterization of a cold-atom vacuum sensor based on laser-cooled Li 6 or Li 7 atoms that will operate in the ultrahigh-vacuum (p\< 10\− 6 Pa) and extreme-high-vacuum (p\< 10\− 10 Pa) regimes. The analysis involves computing the X 2 Σ+ HeLi Born-Oppenheimer potential followed by the numerical solution of the relevant radial Schr{\"o}dinger equation. The potential is computed using a single-reference-coupled-cluster electronic-structure method with basis sets of different completeness in order to characterize our uncertainty budget. We predict that the rate coefficient for a 300 K helium gas and a 1 μ K Li gas is 1.467 (13)\× 10\− 9 cm 3/s for He 4+ Li 6 and 1.471 (13)\× 10\− 9 cm 3/s for He 4+ Li 7, where the \…
},
doi = {https://doi.org/10.1103/PhysRevA.101.012702},
author = {Constantinos Makrides and Daniel S Barker and James A Fedchak and Julia Scherschligt and Stephen Eckel and Eite Tiesinga}
}
@article {2535,
title = {Feshbach resonances in p-wave three-body recombination within Fermi-Fermi mixtures of open-shell 6Li and closed-shell 173Yb atoms},
year = {2019},
month = {12/10/2019},
abstract = {We report on observations and modeling of interspecies magnetic Feshbach resonances in dilute ultracold mixtures of open-shell alkali-metal 6Li and closed-shell 173Yb atoms with temperatures just above quantum degeneracy for both fermionic species. Resonances are located by detecting magnetic-field-dependent atom loss due to three-body recombination. We resolve closely-located resonances that originate from a weak separation-dependent hyperfine coupling between the electronic spin of 6Li and the nuclear spin of 173Yb, and confirm their magnetic field spacing by ab initio electronic-structure calculations. Through quantitative comparisons of theoretical atom-loss profiles and experimental data at various temperatures between 1 μK and 20 μK, we show that three-body recombination in fermionic mixtures has a p-wave Wigner threshold behavior leading to characteristic asymmetric loss profiles. Such resonances can be applied towards the formation of ultracold doublet ground-state molecules and quantum simulation of superfluid p-wave pairing.
},
url = {https://arxiv.org/abs/1912.04874},
author = {Alaina Green and Hui Li and Jun Hui See Toh and Xinxin Tang and Katherine McCormick and Ming Li and Eite Tiesinga and Svetlana Kotochigova and Subhadeep Gupta}
}
@article {2304,
title = {Fractal Universality in Near-Threshold Magnetic Lanthanide Dimers},
journal = {Science Advances},
volume = {4},
year = {2018},
month = {2018/02/16},
pages = {eaap8308},
abstract = {Ergodic quantum systems are often quite alike, whereas nonergodic, fractal systems are unique and display characteristic properties. We explore one of these fractal systems, weakly bound dysprosium lanthanide molecules, in an external magnetic field. As recently shown, colliding ultracold magnetic dysprosium atoms display a soft chaotic behavior with a small degree of disorder. We broaden this classification by investigating the generalized inverse participation ratio and fractal dimensions for large sets of molecular wave functions. Our exact close-coupling simulations reveal a dynamic phase transition from partially localized states to totally delocalized states and universality in its distribution by increasing the magnetic field strength to only a hundred Gauss (or 10 mT). Finally, we prove the existence of nonergodic delocalized phase in the system and explain the violation of ergodicity by strong coupling between near-threshold molecular states and the nearby continuum.
},
doi = {https://doi.org/10.1126/sciadv.aap8308},
url = {https://arxiv.org/abs/1802.09586},
author = {Constantinos Makrides and Ming Li and Eite Tiesinga and Svetlana Kotochigova}
}
@article {2206,
title = {Observation of bound state self-interaction in a nano-eV atom collider},
journal = {Nature Communications },
volume = {9},
year = {2018},
month = {2018/11/20},
abstract = {Quantum mechanical scattering resonances for colliding particles occur when a continuum scattering state couples to a discrete bound state between them. The coupling also causes the bound state to interact with itself via the continuum and leads to a shift in the bound state energy, but, lacking knowledge of the bare bound state energy, measuring this self-energy via the resonance position has remained elusive. Here, we report on the direct observation of self-interaction by using a nano-eV atom collider to track the position of a magnetically-tunable Feshbach resonance through a parameter space spanned by energy and magnetic field. Our system of potassium and rubidium atoms displays a strongly non-monotonic resonance trajectory with an exceptionally large self-interaction energy arising from an interplay between the Feshbach bound state and a different, virtual bound state at a fixed energy near threshold.
},
doi = {https://doi.org/10.1038/s41467-018-07375-8},
url = {https://arxiv.org/abs/1807.01174},
author = {Ryan Thomas and Matthew Chilcott and Eite Tiesinga and Amita B. Deb and Niels Kj{\ae}rgaard}
}
@article {2255,
title = {Orbital quantum magnetism in spin dynamics of strongly interacting magnetic lanthanide atoms},
year = {2018},
abstract = {Laser cooled lanthanide atoms are ideal candidates with which to study strong and unconventional quantum magnetism with exotic phases. Here, we use state-of-the-art closed-coupling simulations to model quantum magnetism for pairs of ultracold spin-6 erbium lanthanide atoms placed in a deep optical lattice. In contrast to the widely used single-channel Hubbard model description of atoms and molecules in an optical lattice, we focus on the single-site multi-channel spin evolution due to spin-dependent contact, anisotropic van der Waals, and dipolar forces. This has allowed us to identify the leading mechanism, orbital anisotropy, that governs molecular spin dynamics among erbium atoms. The large magnetic moment and combined orbital angular momentum of the 4f-shell electrons are responsible for these strong anisotropic interactions and unconventional quantum magnetism. Multi-channel simulations of magnetic Cr atoms under similar trapping conditions show that their spin-evolution is controlled by spin-dependent contact interactions that are distinct in nature from the orbital anisotropy in Er. The role of an external magnetic field and the aspect ratio of the lattice site on spin dynamics is also investigated.
},
url = {https://arxiv.org/abs/1804.10102},
author = {Ming Li and Eite Tiesinga and Svetlana Kotochigova}
}
@article {2303,
title = {A semiclassical theory of phase-space dynamics of interacting bosons},
year = {2018},
abstract = {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.
},
url = {https://arxiv.org/abs/1803.05122},
author = {Ranchu Mathew and Eite Tiesinga}
}
@article {2000,
title = {Above threshold scattering about a Feshbach resonance for ultracold atoms in an optical collider},
journal = {Nature Communications},
volume = {8},
year = {2017},
month = {2017/09/06},
abstract = {Studies of magnetically tunable Feshbach resonances in ultracold atomic gases have predominantly been carried out in the zero collision-energy limit. Here, we explore above threshold collisions at well-defined energies in the vicinity of a narrow magnetic Feshbach resonance by means of a laser-based collider. Our experiment focuses on collisions between ground-state 87Rb atoms in the |F = 2,mF = 0i and |F = 1,mF = 1i hyperfine states, which have a known s-wave resonance at 9.040(7) G at threshold that strongly couples to inelastic channels, where 1 G = 10\−4 T. Using our collider we can track the magnetic field shift in resonance position as the energy is tuned. This presents a challenge due to the narrow width of the resonance in conjunction with inherent broadening mechanisms of the collider. We find, however, that the narrow Feshbach scattering feature becomes imprinted on the spatial distribution of atoms in a fashion that allows for an accurate determination of resonance position as a function of collision energy through a shift in center-of-mass position of the outgoing clouds. This shift has a dispersive line shape with a zero value at the resonance position. We obtain excellent agreement with theory on the resonance position.
},
doi = {10.1038/s41467-017-00458-y},
url = {https://arxiv.org/abs/1704.07109},
author = {Milena S. J. Horvath and Ryan Thomas and Eite Tiesinga and Amita B. Deb and Niels Kj{\ae}rgaard}
}
@article {2305,
title = {Development of a new UHV/XHV pressure standard (cold atom vacuum standard)},
journal = {Metrologia},
volume = {54},
year = {2017},
month = {2017/11/3},
abstract = {The National Institute of Standards and Technology has recently begun a program to develop a primary pressure standard that is based on ultra-cold atoms, covering a pressure range of 1 x 10-6 to 1 x 10-10 Pa and possibly lower. These pressures correspond to the entire ultra-high vacuum range and extend into the extreme-high vacuum. This cold-atom vacuum standard (CAVS) is both a primary standard and absolute sensor of vacuum. The CAVS is based on the loss of cold, sensor atoms (such as the alkali-metal lithium) from a magnetic trap due to collisions with the background gas (primarily H2) in the vacuum. The pressure is determined from a thermally-averaged collision cross section, which is a fundamental atomic property, and the measured loss rate. The CAVS is primary because it will use collision cross sections determined from ab initio calculations for the Li + H2 system. Primary traceability is transferred to other systems of interest using sensitivity coefficients.
},
doi = {https://doi.org/10.1088/1681-7575/aa8a7b},
url = {https://arxiv.org/abs/1801.10120},
author = {Julia Scherschligt and James A Fedchak and Daniel S Barker and Stephen Eckel and Nikolai Klimov and Constantinos Makrides and Eite Tiesinga}
}
@article {1959,
title = {Dispersive optical detection of magnetic Feshbach resonances in ultracold gases},
journal = {Physical Review A},
volume = {96},
year = {2017},
month = {2017/08/18},
pages = {022705},
abstract = {Magnetically tunable Feshbach resonances in ultracold atomic systems are chiefly identified and characterized through time consuming atom loss spectroscopy. We describe an off-resonant dispersive optical probing technique to rapidly locate Feshbach resonances and demonstrate the method by locating four resonances of\ 87Rb, between the\ |F=1,mF=1\〉\ and\ |F=2,mF=0\〉\ states. Despite the loss features being\ ≲100\ mG wide, we require only 21 experimental runs to explore a magnetic field range \>18 G. The resonances consist of two known s-wave features in the vicinity of 9 G and 18 G and two previously unobserved p-wave features near 5 G and 10 G. We further utilize the dispersive approach to directly characterize the two-body loss dynamics for each Feshbach resonance.
},
doi = {10.1103/PhysRevA.96.022705},
url = {https://arxiv.org/abs/1702.02216},
author = {Bianca J. Sawyer and Milena S. J. Horvath and Eite Tiesinga and Amita B. Deb and Niels Kj{\ae}rgaard}
}
@article {1958,
title = {Pendular trapping conditions for ultracold polar molecules enforced by external electric fields},
journal = {Physical Review A},
volume = {95},
year = {2017},
month = {2017/06/26},
pages = {063422},
abstract = {We theoretically investigate trapping conditions for ultracold polar molecules in optical lattices, when external magnetic and electric fields are simultaneously applied. Our results are based on an accurate electronic-structure calculation of the polar\ 23Na40K polar molecule in its absolute ground state combined with a calculation of its rovibrational-hyperfine motion. We find that an electric field strength of\ 5.26(15)\ kV/cm and an angle of\ 54.7o\ between this field and the polarization of the optical laser lead to a trapping design for\ 23Na40K molecules where decoherences due laser-intensity fluctuations and fluctuations in the direction of its polarization are kept to a minimum. One standard deviation systematic and statistical uncertainties are given in parenthesis. Under such conditions pairs of hyperfine-rotational states of\ v=0\ molecules, used to induce tunable dipole-dipole interactions between them, experience ultrastable, matching trapping forces.
},
doi = {10.1103/PhysRevA.95.063422},
url = {https://arxiv.org/abs/1703.03839},
author = {Ming Li and Alexander Petrov and Constantinos Makrides and Eite Tiesinga and Svetlanta Kotochigova}
}
@article {1999,
title = {Phase-space mixing in dynamically unstable, integrable few-mode quantum systems},
journal = {Physical Review A},
volume = {96},
year = {2017},
month = {2017/07/05},
pages = {013604},
abstract = {Quenches in isolated quantum systems are currently a subject of intense study. Here, we consider quantum few-mode systems that are integrable in their classical mean-field limit and become dynamically unstable after a quench of a system parameter. Specifically, we study a Bose-Einstein condensate (BEC) in a double-well potential and an antiferromagnetic spinor BEC constrained to a single spatial mode. We study the time dynamics after the quench within the truncated Wigner approximation (TWA) and find that system relaxes to a steady state due to phase-space mixing. Using the action-angle formalism and a pendulum as an illustration, we derive general analytical expressions for the time evolution of expectation values of observables and their long-time limits. We find that the deviation of the long-time expectation value from its classical value scales as 1/O(ln N), where N is the number of atoms in the condensate. Furthermore, the relaxation of an observable to its steady state value is a damped oscillation and the damping is Gaussian in time. We confirm our results with numerical TWA simulations.
},
doi = {10.1103/PhysRevA.96.013604},
url = {https://arxiv.org/abs/1705.01702},
author = {Ranchu Mathew and Eite Tiesinga}
}
@article {1781,
title = {A Hubbard model for ultracold bosonic atoms interacting via zero-point-energy induced three-body interactions},
journal = {Physical Review A},
volume = {93},
year = {2016},
month = {2016/04/19},
pages = {043616},
abstract = {We show that for ultra-cold neutral bosonic atoms held in a three-dimensional periodic potential or optical lattice, a Hubbard model with dominant, attractive three-body interactions can be generated. In fact, we derive that the effect of pair-wise interactions can be made small or zero starting from the realization that collisions occur at the zero-point energy of an optical lattice site and the strength of the interactions is energy dependent from effective-range contributions. We determine the strength of the two- and three-body interactions for scattering from van-der-Waals potentials and near Fano-Feshbach resonances. For van-der-Waals potentials, which for example describe scattering of alkaline-earth atoms, we find that the pair-wise interaction can only be turned off for species with a small negative scattering length, leaving the 88Sr isotope a possible candidate. Interestingly, for collisional magnetic Feshbach resonances this restriction does not apply and there often exist magnetic fields where the two-body interaction is small. We illustrate this result for several known narrow resonances between alkali-metal atoms as well as chromium atoms. Finally, we compare the size of the three-body interaction with hopping rates and describe limits due to three-body recombination.
},
doi = {10.1103/PhysRevA.93.043616},
url = {http://journals.aps.org/pra/abstract/10.1103/PhysRevA.93.043616},
author = {Saurabh Paul and P. R. Johnson and Eite Tiesinga}
}
@article {1914,
title = {Multiple scattering dynamics of fermions at an isolated p-wave resonance},
journal = {Nature Communications},
volume = {7},
year = {2016},
month = {2016/07/11},
pages = {12069},
abstract = {The wavefunction for indistinguishable fermions is anti-symmetric under particle exchange, which directly leads to the Pauli exclusion principle, and hence underlies the structure of atoms and the properties of almost all materials. In the dynamics of collisions between two indistinguishable fermions this requirement strictly prohibits scattering into 90 degree angles. Here we experimentally investigate the collisions of ultracold clouds fermionic\ 40K\ atoms by directly measuring scattering distributions. With increasing collision energy we identify the Wigner threshold for p-wave scattering with its tell-tale dumb-bell shape and no\ 90o\ yield. Above this threshold effects of multiple scattering become manifest as deviations from the underlying binary p-wave shape, adding particles either isotropically or axially. A shape resonance for\ 40K\ facilitates the separate observation of these two processes. The isotropically enhanced multiple scattering mode is a generic p-wave threshold phenomenon, while the axially enhanced mode should occur in any colliding particle system with an elastic scattering resonance.
},
doi = {10.1038/ncomms12069},
url = {http://www.nature.com/articles/ncomms12069},
author = {Ryan Thomas and Kris O. Roberts and Eite Tiesinga and Andrew C.J. Wade and P. Blair Blakie and Amita B. Deb and Niels Kj{\ae}rgaard}
}
@article {1697,
title = {Photoassociation of spin polarized Chromium},
journal = {Physical Review A},
volume = {93},
year = {2016},
month = {2016/02/29},
pages = {021406},
abstract = {We report the homonuclear photoassociation (PA) of ultracold 52Cr atoms in an optical dipole trap. This constitutes the first measurement of PA in an element with total electron spin S~>1. Although Cr, with its 7S3 ground and 7P4,3,2 excited states, is expected to have a complicated PA spectrum we show that a spin polarized cloud exhibits a remarkably simple PA spectrum when circularly polarized light is applied. Over a scan range of 20 GHz below the 7P3 asymptote we observe two distinct vibrational series each following a LeRoy-Bernstein law for a C3/R3 potential with excellent agreement. We determine the C3 coefficients of the Hund{\textquoteright}s case c) relativistic adiabatic potentials to be -1.83{\textpm}0.02 a.u. and -1.46{\textpm}0.01a.u.. Theoretical non-rotating Movre-Pichler calculations enable a first assignment of the series to Ω=6u and 5g potential energy curves. In a different set of experiments we disturb the selection rules by a transverse magnetic field which leads to additional PA series.},
doi = {10.1103/PhysRevA.93.021406},
url = {http://arxiv.org/abs/1512.04378},
author = {Jahn R{\"u}hrig and Tobias B{\"a}uerle and Paul S. Julienne and Eite Tiesinga and Tilman Pfau}
}
@article {1782,
title = {Sudden-quench dynamics of Bardeen-Cooper-Schrieffer states in deep optical lattices},
journal = {Physical Review A},
volume = {94},
year = {2016},
month = {2016/08/05},
pages = {023607},
abstract = {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.
},
doi = {http://dx.doi.org/10.1103/PhysRevA.94.023607},
url = {http://arxiv.org/abs/1602.00979},
author = {Marlon Nuske and L. Mathey and Eite Tiesinga}
}
@article {1823,
title = {Wannier functions using a discrete variable representation for optical lattices},
journal = {Physical Review A},
volume = {94},
year = {2016},
month = {2016/09/07},
pages = {033606},
abstract = {We propose a numerical method using the discrete variable representation (DVR) for constructing real-valued Wannier functions localized in a unit cell for both symmetric and asymmetric periodic potentials. We apply these results to finding Wannier functions for ultracold atoms trapped in laser-generated optical lattices. Following S. Kivelson [Phys. Rev. B\ 26, 4269 (1982)], for a symmetric lattice with inversion symmetry, we construct Wannier functions as eigenstates of the position operators\ x\ˆ,\ y\ˆ, and\ z\ˆ\ restricted to single-particle Bloch functions belonging to one or more bands. To ensure that the Wannier functions are real-valued, we numerically obtain the band structure and real-valued eigenstates using a uniform Fourier grid DVR. We then show, by a comparison of tunneling energies, that the Wannier functions are accurate for both inversion-symmetric and asymmetric potentials to better than 10 significant digits when using double-precision arithmetic. The calculations are performed for an optical lattice with double-wells per unit cell with tunable asymmetry along the\ x\ axis and a single sinusoidal potential along the perpendicular directions. Localized functions at the two potential minima within each unit cell are similarly constructed, but using a superposition of single-particle solutions from the two lowest bands. We finally use these localized basis functions to determine the two-body interaction energies in the Bose-Hubbard model and show the dependence of these energies on lattice asymmetry.
},
doi = {http://dx.doi.org/10.1103/PhysRevA.94.033606},
url = {http://journals.aps.org/pra/abstract/10.1103/PhysRevA.94.033606},
author = {Saurabh Paul and Eite Tiesinga}
}
@article {1274,
title = {Large effective three-body interaction in a double-well optical lattice},
journal = {Phys. Rev. A 92, 023602},
volume = {92},
year = {2015},
month = {2015/08/03},
pages = {023602},
abstract = { We study ultracold atoms in an optical lattice with two local minima per unit
cell and show that the low energy states of a multi-band Bose-Hubbard (BH)
Hamiltonian with only pair-wise interactions is equivalent to an effective
single-band Hamiltonian with strong three-body interactions. We focus on a
double-well optical lattice with a symmetric double well along the $x$ axis and
single well structure along the perpendicular directions. Tunneling and
two-body interaction energies are obtained from an exact band-structure
calculation and numerically-constructed Wannier functions in order to construct
a BH Hamiltonian spanning the lowest two bands. Our effective Hamiltonian is
constructed from the ground state of the $N$-atom Hamiltonian for each unit
cell obtained within the subspace spanned by the Wannier functions of two
lowest bands. The model includes hopping between ground states of neighboring
unit cells. We show that such an effective Hamiltonian has strong three-body
interactions that can be easily tuned by changing the lattice parameters.
Finally, relying on numerical mean-field simulations, we show that the
effective Hamiltonian is an excellent approximation of the two-band BH
Hamiltonian over a wide range of lattice parameters, both in the superfluid and
Mott insulator regions.
},
url = {http://journals.aps.org/pra/abstract/10.1103/PhysRevA.92.023602},
author = {Saurabh Paul and Eite Tiesinga}
}
@article {1282,
title = {Optimization of collisional Feshbach cooling of an ultracold nondegenerate gas},
journal = {Physical Review A},
volume = {91},
year = {2015},
month = {2015/04/20},
pages = {043626},
abstract = { We optimize a collision-induced cooling process for ultracold atoms in the
nondegenerate regime. It makes use of a Feshbach resonance, instead of rf
radiation in evaporative cooling, to selectively expel hot atoms from a trap.
Using functional minimization we analytically show that for the optimal cooling
process the resonance energy must be tuned such that it linearly follows the
temperature. Here, optimal cooling is defined as maximizing the phase-space
density after a fixed cooling duration. The analytical results are confirmed by
numerical Monte-Carlo simulations. In order to simulate more realistic
experimental conditions, we show that background losses do not change our
conclusions, while additional non-resonant two-body losses make a lower initial
resonance energy with non-linear dependence on temperature preferable.
},
doi = {10.1103/PhysRevA.91.043626},
url = {http://arxiv.org/abs/1412.8473v1},
author = {Marlon Nuske and Eite Tiesinga and L. Mathey}
}
@article {1304,
title = {Self-heterodyne detection of the {\it in-situ} phase of an atomic-SQUID},
journal = {Physical Review A},
volume = {92},
year = {2015},
month = {2015/09/03},
pages = {033602},
abstract = { 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.
},
doi = {10.1103/PhysRevA.92.033602},
url = {http://arxiv.org/abs/1506.09149v2},
author = {Ranchu Mathew and Avinash Kumar and Stephen Eckel and Fred Jendrzejewski and Gretchen K. Campbell and Mark Edwards and Eite Tiesinga}
}
@article {1295,
title = {Spin-orbit-coupled topological Fulde-Ferrell states of fermions in a harmonic trap
},
journal = {Physical Review A},
volume = {90},
year = {2014},
month = {2014/11/7},
abstract = { 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.
},
doi = {10.1103/PhysRevA.90.053606},
url = {http://arxiv.org/abs/1404.6211v1},
author = {Lei Jiang and Eite Tiesinga and Xia-Ji Liu and Hui Hu and Han Pu}
}
@article {1272,
title = {Controlling the group velocity of colliding atomic Bose-Einstein condensates with Feshbach resonances
},
journal = {Physical Review A},
volume = {87},
year = {2013},
month = {2013/5/10},
abstract = { We report on a proposal to change the group velocity of a small Bose Einstein
Condensate (BEC) upon collision with another BEC in analogy to slowing of light
passing through dispersive media. We make use of ultracold collisions near a
magnetic Feshbach resonance, which gives rise to a sharp variation in
scattering length with collision energy and thereby changes the group velocity.
A generalized Gross-Pitaveskii equation is derived for a small BEC moving
through a larger stationary BEC. We denote the two condensates by laser and
medium BEC, respectively, to highlight the analogy to a laser pulse travelling
through a medium. We derive an expression for the group velocity in a
homogeneous medium as well as for the difference in distance, $\delta$, covered
by the laser BEC in the presence and absence of a finite-sized medium BEC with
a Thomas-Fermi density distribution. For a medium and laser of the same
isotopic species, the shift $\delta$ has an upper bound of twice the
Thomas-Fermi radius of the medium. For typical narrow Feshbach resonances and a
medium with number density $10^{15}$ cm$^{-3}$ up to 85\% of the upper bound can
be achieved, making the effect experimentally observable. We also derive
constraints on the experimental realization of our proposal.
},
doi = {10.1103/PhysRevA.87.053608},
url = {http://arxiv.org/abs/1301.4234v2},
author = {Ranchu Mathew and Eite Tiesinga}
}
@article {1273,
title = {Formation and decay of Bose-Einstein condensates in an excited band of a double-well optical lattice
},
journal = {Physical Review A},
volume = {88},
year = {2013},
month = {2013/9/12},
abstract = { We study the formation and collision-aided decay of an ultra-cold atomic
Bose-Einstein condensate in the first excited band of a double-well 2D-optical
lattice with weak harmonic confinement in the perpendicular $z$ direction. This
lattice geometry is based on an experiment by Wirth et al. The double well is
asymmetric, with the local ground state in the shallow well nearly degenerate
with the first excited state of the adjacent deep well. We compare the band
structure obtained from a tight-binding (TB) model with that obtained
numerically using a plane wave basis. We find the TB model to be in
quantitative agreement for the lowest two bands, qualitative for next two
bands, and inadequate for even higher bands. The band widths of the excited
bands are much larger than the harmonic oscillator energy spacing in the $z$
direction. We then study the thermodynamics of a non-interacting Bose gas in
the first excited band. We estimate the condensate fraction and critical
temperature, $T_c$, as functions of lattice parameters. For typical atom
numbers, the critical energy $k_BT_c$, with $k_B$ the Boltzmann constant, is
larger than the excited band widths and harmonic oscillator energy. Using
conservation of total energy and atom number, we show that the temperature
increases after the lattice transformation. Finally, we estimate the time scale
for a two-body collision-aided decay of the condensate as a function of lattice
parameters. The decay involves two processes, the dominant one in which both
colliding atoms decay to the ground band, and the second involving excitation
of one atom to a higher band. For this estimate, we have used TB wave functions
for the lowest four bands, and numerical estimates for higher bands. The decay
rate rapidly increases with lattice depth, but stays smaller than the tunneling
rate between the $s$ and $p$ orbitals in adjacent wells.
},
doi = {10.1103/PhysRevA.88.033615},
url = {http://arxiv.org/abs/1308.4449v1},
author = {Saurabh Paul and Eite Tiesinga}
}
@article {1281,
title = {Quadrature interferometry for nonequilibrium ultracold bosons in optical lattices
},
journal = {Physical Review A},
volume = {87},
year = {2013},
month = {2013/1/22},
abstract = { We develop an interferometric technique for making time-resolved measurements
of field-quadrature operators for nonequilibrium ultracold bosons in optical
lattices. The technique exploits the internal state structure of magnetic atoms
to create two subsystems of atoms in different spin states and lattice sites. A
Feshbach resonance turns off atom-atom interactions in one spin subsystem,
making it a well-characterized reference state, while atoms in the other
subsystem undergo nonequilibrium dynamics for a variable hold time. Interfering
the subsystems via a second beam-splitting operation, time-resolved quadrature
measurements on the interacting atoms are obtained by detecting relative spin
populations. The technique can provide quadrature measurements for a variety of
Hamiltonians and lattice geometries (e.g., cubic, honeycomb, superlattices),
including systems with tunneling, spin-orbit couplings using artificial gauge
fields, and higher-band effects. Analyzing the special case of a deep lattice
with negligible tunneling, we obtain the time evolution of both quadrature
observables and their fluctuations. As a second application, we show that the
interferometer can be used to measure atom-atom interaction strengths with
super-Heisenberg scaling n^(-3/2) in the mean number of atoms per lattice site
n, and standard quantum limit scaling M^(-1/2) in the number of lattice sites
M. In our analysis, we require M >> 1 and for realistic systems n is small, and
therefore the scaling in total atom number N = nM is below the Heisenberg
limit; nevertheless, measurements testing the scaling behaviors for
interaction-based quantum metrologies should be possible in this system.
},
doi = {10.1103/PhysRevA.87.013423},
url = {http://arxiv.org/abs/1212.1193v2},
author = {Eite Tiesinga and Philip R. Johnson}
}
@article {1287,
title = {Soliton dynamics of an atomic spinor condensate on a Ring Lattice},
journal = {Physical Review A},
volume = {87},
year = {2013},
month = {2013/3/6},
abstract = { 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.
},
doi = {10.1103/PhysRevA.87.033608},
url = {http://arxiv.org/abs/1301.5851v1},
author = {Indubala I Satija and Carlos L. Pando and Eite Tiesinga}
}
@article {1306,
title = {Spinor dynamics in an antiferromagnetic spin-1 thermal Bose gas},
journal = {Physical Review Letters},
volume = {111},
year = {2013},
month = {2013/7/9},
abstract = { 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.
},
doi = {10.1103/PhysRevLett.111.025301},
url = {http://arxiv.org/abs/1306.4255v1},
author = {Hyewon K. Pechkis and Jonathan P. Wrubel and Arne Schwettmann and Paul F. Griffin and Ryan Barnett and Eite Tiesinga and Paul D. Lett}
}
@article {1279,
title = {Anisotropy induced Feshbach resonances in a quantum dipolar gas of magnetic atoms
},
journal = {Physical Review Letters},
volume = {109},
year = {2012},
month = {2012/9/7},
abstract = { We explore the anisotropic nature of Feshbach resonances in the collision
between ultracold magnetic submerged-shell dysprosium atoms, which can only
occur due to couplings to rotating bound states. This is in contrast to
well-studied alkali-metal atom collisions, where most Feshbach resonances are
hyperfine induced and due to rotation-less bound states. Our novel
first-principle coupled-channel calculation of the collisions between
open-4f-shell spin-polarized bosonic dysprosium reveals a striking correlation
between the anisotropy due to magnetic dipole-dipole and electrostatic
interactions and the Feshbach spectrum as a function of an external magnetic
field. Over a 20 mT magnetic field range we predict about a dozen Feshbach
resonances and show that the resonance locations are exquisitely sensitive to
the dysprosium isotope.
},
doi = {10.1103/PhysRevLett.109.103002},
url = {http://arxiv.org/abs/1203.4172v1},
author = {Alexander Petrov and Eite Tiesinga and Svetlana Kotochigova}
}
@article {1294,
title = {Resonant control of polar molecules in an optical lattice},
journal = {Physical Review A},
volume = {85},
year = {2012},
month = {2012/2/8},
abstract = { We study the resonant control of two nonreactive polar molecules in an
optical lattice site, focussing on the example of RbCs. Collisional control can
be achieved by tuning bound states of the intermolecular dipolar potential, by
varying the applied electric field or trap frequency. We consider a wide range
of electric fields and trapping geometries, showing that a three-dimensional
optical lattice allows for significantly wider avoided crossings than free
space or quasi-two dimensional geometries. Furthermore, we find that dipolar
confinement induced resonances can be created with reasonable trapping
frequencies and electric fields, and have widths that will enable useful
control in forthcoming experiments.
},
doi = {10.1103/PhysRevA.85.022703},
url = {http://arxiv.org/abs/1111.0227v1},
author = {Thomas M. Hanna and Eite Tiesinga and William F. Mitchell and Paul S. Julienne}
}
@article {1303,
title = {Detecting paired and counterflow superfluidity via dipole oscillations},
journal = {Physical Review A},
volume = {84},
year = {2011},
month = {2011/10/27},
abstract = { 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.
},
doi = {10.1103/PhysRevA.84.041609},
url = {http://arxiv.org/abs/1103.3513v3},
author = {Anzi Hu and L. Mathey and Eite Tiesinga and Ippei Danshita and Carl J. Williams and Charles W. Clark}
}
@article {1301,
title = {Spatial separation in a thermal mixture of ultracold $^{174}$Yb and $^{87}$Rb atoms
},
journal = {Physical Review A},
volume = {83},
year = {2011},
month = {2011/4/21},
abstract = { 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.
},
doi = {10.1103/PhysRevA.83.040702},
url = {http://arxiv.org/abs/1104.1722v1},
author = {Florian Baumer and Frank M{\"u}nchow and Axel G{\"o}rlitz and Stephen E. Maxwell and Paul S. Julienne and Eite Tiesinga}
}
@article {1278,
title = {Superradiance of cold atoms coupled to a superconducting circuit},
journal = {Physical Review A},
volume = {83},
year = {2011},
month = {2011/6/6},
abstract = { 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.
},
doi = {10.1103/PhysRevA.83.062305},
url = {http://arxiv.org/abs/1101.5300v1},
author = {Daniel Braun and Jonathan Hoffman and Eite Tiesinga}
}
@article {1286,
title = {Creation and manipulation of Feshbach resonances with radio-frequency radiation
},
journal = {New Journal of Physics},
volume = {12},
year = {2010},
month = {2010/08/12},
pages = {083031},
abstract = { We present a simple technique for studying collisions of ultracold atoms in
the presence of a magnetic field and radio-frequency radiation (rf). Resonant
control of scattering properties can be achieved by using rf to couple a
colliding pair of atoms to a bound state. We show, using the example of 6Li,
that in some ranges of rf frequency and magnetic field this can be done without
giving rise to losses. We also show that halo molecules of large spatial extent
require much less rf power than deeply bound states. Another way to exert
resonant control is with a set of rf-coupled bound states, linked to the
colliding pair through the molecular interactions that give rise to
magnetically tunable Feshbach resonances. This was recently demonstrated for
87Rb [Kaufman et al., Phys. Rev. A 80:050701(R), 2009]. We examine the
underlying atomic and molecular physics which made this possible. Lastly, we
consider the control that may be exerted over atomic collisions by placing
atoms in superpositions of Zeeman states, and suggest that it could be useful
where small changes in scattering length are required. We suggest other species
for which rf and magnetic field control could together provide a useful tuning
mechanism.
},
doi = {10.1088/1367-2630/12/8/083031},
url = {http://arxiv.org/abs/1004.0636v1},
author = {Thomas M. Hanna and Eite Tiesinga and Paul S. Julienne}
}
@article {1284,
title = {Feshbach Resonances in Ultracold Gases},
journal = {Reviews of Modern Physics},
volume = {82},
year = {2010},
month = {2010/4/29},
pages = {1225 - 1286},
abstract = { Feshbach resonances are the essential tool to control the interaction between
atoms in ultracold quantum gases. They have found numerous experimental
applications, opening up the way to important breakthroughs. This Review
broadly covers the phenomenon of Feshbach resonances in ultracold gases and
their main applications. This includes the theoretical background and models
for the description of Feshbach resonances, the experimental methods to find
and characterize the resonances, a discussion of the main properties of
resonances in various atomic species and mixed atomic species systems, and an
overview of key experiments with atomic Bose-Einstein condensates, degenerate
Fermi gases, and ultracold molecules.
},
doi = {10.1103/RevModPhys.82.1225},
url = {http://arxiv.org/abs/0812.1496v2},
author = {Cheng Chin and Rudolf Grimm and Paul Julienne and Eite Tiesinga}
}
@article {1293,
title = {Collisional cooling of ultra-cold atom ensembles using Feshbach resonances
},
journal = {Physical Review A},
volume = {80},
year = {2009},
month = {2009/9/8},
abstract = { We propose a new type of cooling mechanism for ultra-cold fermionic atom
ensembles, which capitalizes on the energy dependence of inelastic collisions
in the presence of a Feshbach resonance. We first discuss the case of a single
magnetic resonance, and find that the final temperature and the cooling rate is
limited by the width of the resonance. A concrete example, based on a p-wave
resonance of $^{40}$K, is given. We then improve upon this setup by using both
a very sharp optical or radio-frequency induced resonance and a very broad
magnetic resonance and show that one can improve upon temperatures reached with
current technologies.
},
doi = {10.1103/PhysRevA.80.030702},
url = {http://arxiv.org/abs/0903.2568v1},
author = {L. Mathey and Eite Tiesinga and Paul S. Julienne and Charles W. Clark}
}
@article {1299,
title = {Counterflow and paired superfluidity in one-dimensional Bose mixtures in optical lattices
},
journal = {Physical Review A},
volume = {80},
year = {2009},
month = {2009/8/24},
abstract = { 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.
},
doi = {10.1103/PhysRevA.80.023619},
url = {http://arxiv.org/abs/0906.2150v1},
author = {Anzi Hu and L. Mathey and Ippei Danshita and Eite Tiesinga and Carl J. Williams and Charles W. Clark}
}
@article {1280,
title = {Multi-channel modelling of the formation of vibrationally cold polar KRb molecules
},
journal = {New Journal of Physics},
volume = {11},
year = {2009},
month = {2009/05/14},
pages = {055043},
abstract = { We describe the theoretical advances that influenced the experimental
creation of vibrationally and translationally cold polar $^{40}$K$^{87}$Rb
molecules \cite{nphys08,science08}. Cold molecules were created from
very-weakly bound molecules formed by magnetic field sweeps near a Feshbach
resonance in collisions of ultra-cold $^{40}$K and $^{87}$Rb atoms. Our
analysis include the multi-channel bound-state calculations of the hyperfine
and Zeeman mixed X$^1\Sigma^+$ and a$^3\Sigma^+$ vibrational levels. We find
excellent agreement with the hyperfine structure observed in experimental data.
In addition, we studied the spin-orbit mixing in the intermediate state of the
Raman transition. This allowed us to investigate its effect on the
vibrationally-averaged transition dipole moment to the lowest ro-vibrational
level of the X$^1\Sigma^+$ state. Finally, we obtained an estimate of the
polarizability of the initial and final ro-vibrational states of the Raman
transition near frequencies relevant for optical trapping of the molecules.
},
doi = {10.1088/1367-2630/11/5/055043},
url = {http://arxiv.org/abs/0901.1486v1},
author = {Svetlana Kotochigova and Eite Tiesinga and Paul S. Julienne}
}
@article {1298,
title = {Number Fluctuations and Energy Dissipation in Sodium Spinor Condensates},
journal = {Physical Review Letters},
volume = {102},
year = {2009},
month = {2009/6/5},
abstract = { We characterize fluctuations in atom number and spin populations in F=1
sodium spinor condensates. We find that the fluctuations enable a quantitative
measure of energy dissipation in the condensate. The time evolution of the
population fluctuations shows a maximum. We interpret this as evidence of a
dissipation-driven separatrix crossing in phase space. For a given initial
state, the critical time to the separatrix crossing is found to depend
exponentially on the magnetic field and linearly on condensate density. This
crossing is confirmed by tracking the energy of the spinor condensate as well
as by Faraday rotation spectroscopy. We also introduce a phenomenological model
that describes the observed dissipation with a single coefficient.
},
doi = {10.1103/PhysRevLett.102.225301},
url = {http://arxiv.org/abs/0906.2110v1},
author = {Yingmei Liu and Eduardo Gomez and Stephen E. Maxwell and Lincoln D. Turner and Eite Tiesinga and Paul D. Lett}
}
@article {1285,
title = {Prediction of Feshbach resonances from three input parameters},
journal = {Physical Review A},
volume = {79},
year = {2009},
month = {2009/4/30},
abstract = { We have developed a model of Feshbach resonances in gases of ultracold alkali
metal atoms using the ideas of multichannel quantum defect theory. Our model
requires just three parameters describing the interactions - the singlet and
triplet scattering lengths, and the long range van der Waals coefficient - in
addition to known atomic properties. Without using any further details of the
interactions, our approach can accurately predict the locations of resonances.
It can also be used to find the singlet and triplet scattering lengths from
measured resonance data. We apply our technique to $^{6}$Li--$^{40}$K and
$^{40}$K--$^{87}$Rb scattering, obtaining good agreement with experimental
results, and with the more computationally intensive coupled channels
technique.
},
doi = {10.1103/PhysRevA.79.040701},
url = {http://arxiv.org/abs/0903.0884v2},
author = {Thomas M. Hanna and Eite Tiesinga and Paul S. Julienne}
}
@article {1302,
title = {Quantum Phase Transitions and Continuous Observation of Spinor Dynamics in an Antiferromagnetic Condensate
},
journal = {Physical Review Letters},
volume = {102},
year = {2009},
month = {2009/3/23},
abstract = { Condensates of spin-1 sodium display rich spin dynamics due to the
antiferromagnetic nature of the interactions in this system. We use Faraday
rotation spectroscopy to make a continuous and minimally destructive
measurement of the dynamics over multiple spin oscillations on a single
evolving condensate. This method provides a sharp signature to locate a
magnetically tuned separatrix in phase space which depends on the net
magnetization. We also observe a phase transition from a two- to a
three-component condensate at a low but finite temperature using a
Stern-Gerlach imaging technique. This transition should be preserved as a
zero-temperature quantum phase transition.
},
doi = {10.1103/PhysRevLett.102.125301},
url = {http://arxiv.org/abs/0902.3189v1},
author = {Yingmei Liu and Sebastian Jung and Stephen E. Maxwell and Lincoln D. Turner and Eite Tiesinga and Paul. D. Lett}
}
@article {1283,
title = {Avoided crossings between bound states of ultracold Cesium dimers},
journal = {Physical Review A},
volume = {78},
year = {2008},
month = {2008/11/5},
abstract = { We present an efficient new computational method for calculating the binding
energies of the bound states of ultracold alkali-metal dimers in the presence
of magnetic fields. The method is based on propagation of coupled differential
equations and does not use a basis set for the interatomic distance coordinate.
It is much more efficient than the previous method based on a radial basis set
and allows many more spin channels to be included. This is particularly
important in the vicinity of avoided crossings between bound states. We
characterize a number of different avoided crossings in Cs_2 and compare our
converged calculations with experimental results. Small but significant
discrepancies are observed in both crossing strengths and level positions,
especially for levels with l symmetry (rotational angular momentum L=8). The
discrepancies should allow the development of improved potential models in the
future.
},
doi = {10.1103/PhysRevA.78.052703},
url = {http://arxiv.org/abs/0806.2583v1},
author = {Jeremy M. Hutson and Eite Tiesinga and Paul S. Julienne}
}
@article {1305,
title = {Multilevel effects in the Rabi oscillations of a Josephson phase qubit},
journal = {Physical Review B},
volume = {78},
year = {2008},
month = {2008/9/15},
abstract = { We present Rabi oscillation measurements of a Nb/AlOx/Nb dc superconducting
quantum interference device (SQUID) phase qubit with a 100 um^2 area junction
acquired over a range of microwave drive power and frequency detuning. Given
the slightly anharmonic level structure of the device, several excited states
play an important role in the qubit dynamics, particularly at high power. To
investigate the effects of these levels, multiphoton Rabi oscillations were
monitored by measuring the tunneling escape rate of the device to the voltage
state, which is particularly sensitive to excited state population. We compare
the observed oscillation frequencies with a simplified model constructed from
the full phase qubit Hamiltonian and also compare time-dependent escape rate
measurements with a more complete density-matrix simulation. Good quantitative
agreement is found between the data and simulations, allowing us to identify a
shift in resonance (analogous to the ac Stark effect), a suppression of the
Rabi frequency, and leakage to the higher excited states.
},
doi = {10.1103/PhysRevB.78.104510},
url = {http://arxiv.org/abs/0806.4711v2},
author = {S. K. Dutta and Frederick W. Strauch and R. M. Lewis and Kaushik Mitra and Hanhee Paik and T. A. Palomaki and Eite Tiesinga and J. R. Anderson and Alex J. Dragt and C. J. Lobb and F. C. Wellstood}
}
@article {1300,
title = {Quantum behavior of the dc SQUID phase qubit},
journal = {Physical Review B},
volume = {77},
year = {2008},
month = {2008/6/13},
abstract = { We analyze the behavior of a dc Superconducting Quantum Interference Device
(SQUID) phase qubit in which one junction acts as a phase qubit and the rest of
the device provides isolation from dissipation and noise in the bias leads.
Ignoring dissipation, we find the two-dimensional Hamiltonian of the system and
use numerical methods and a cubic approximation to solve Schrodinger{\textquoteright}s equation
for the eigenstates, energy levels, tunneling rates, and expectation value of
the currents in the junctions. Using these results, we investigate how well
this design provides isolation while preserving the characteristics of a phase
qubit. In addition, we show that the expectation value of current flowing
through the isolation junction depends on the state of the qubit and can be
used for non-destructive read out of the qubit state.
},
doi = {10.1103/PhysRevB.77.214512},
url = {http://arxiv.org/abs/0805.3680v1},
author = {Kaushik Mitra and F. W. Strauch and C. J. Lobb and J. R. Anderson and F. C. Wellstood and Eite Tiesinga}
}
@article {1292,
title = {Tunneling phase gate for neutral atoms in a double-well lattice},
journal = {Physical Review A},
volume = {77},
year = {2008},
month = {2008/5/12},
abstract = { We propose a new two--qubit phase gate for ultra--cold atoms confined in an
experimentally realized tilted double--well optical lattice [Sebby--Strabley et
al., Phys. Rev. A {\bf 73} 033605 (2006)]. Such a lattice is capable of
confining pairs of atoms in a two--dimensional array of double--well potentials
where control can be exercised over the barrier height and the energy
difference of the minima of the two wells (known as the {\textquoteleft}{\textquoteleft}tilt{\textquoteright}{\textquoteright}). The four
lowest single--particle motional states consist of two pairs of motional states
in which each pair is localized on one side of the central barrier, allowing
for two atoms confined in such a lattice to be spatially separated qubits. We
present a time--dependent scheme to manipulate the tilt to induce tunneling
oscillations which produce a collisional phase gate. Numerical simulations
demonstrate that this gate can be performed with high fidelity.
},
doi = {10.1103/PhysRevA.77.050304},
url = {http://arxiv.org/abs/0712.1856v1},
author = {Frederick W. Strauch and Mark Edwards and Eite Tiesinga and Carl J. Williams and Charles W. Clark}
}
@article {1276,
title = {Two-body transients in coupled atomic-molecular BECs},
journal = {Physical Review Letters},
volume = {100},
year = {2008},
month = {2008/3/3},
abstract = { We discuss the dynamics of an atomic Bose-Einstein condensate when pairs of
atoms are converted into molecules by single-color photoassociation. Three main
regimes are found and it is shown that they can be understood on the basis of
time-dependent two-body theory. In particular, the so-called rogue dissociation
regime [Phys. Rev. Lett., 88, 090403 (2002)], which has a density-dependent
limit on the photoassociation rate, is identified with a transient regime of
the two-atom dynamics exhibiting universal properties. Finally, we illustrate
how these regimes could be explored by photoassociating condensates of
alkaline-earth atoms.
},
doi = {10.1103/PhysRevLett.100.093001},
url = {http://arxiv.org/abs/0707.2963v2},
author = {Pascal Naidon and Eite Tiesinga and Paul S. Julienne}
}
@article {1277,
title = {Coherent, adiabatic and dissociation regimes in coupled atomic-molecular Bose-Einstein condensates
},
year = {2007},
month = {2007/11/02},
abstract = { We discuss the dynamics of a Bose-Einstein condensate of atoms which is
suddenly coupled to a condensate of molecules by an optical or magnetic
Feshbach resonance. Three limiting regimes are found and can be understood from
the transient dynamics occuring for each pair of atoms. This transient dynamics
can be summarised into a time-dependent shift and broadening of the molecular
state. A simple Gross-Pitaevskii picture including this shift and broadening is
proposed to describe the system in the three regimes. Finally, we suggest how
to explore these regimes experimentally.
},
url = {http://arxiv.org/abs/0711.0397v2},
author = {Pascal Naidon and Eite Tiesinga and Paul S. Julienne}
}
@article {1291,
title = {Effective-range description of a Bose gas under strong one- or two-dimensional confinement
},
journal = {New Journal of Physics},
volume = {9},
year = {2007},
month = {2007/01/29},
pages = {19 - 19},
abstract = { We point out that theories describing s-wave collisions of bosonic atoms
confined in one- or two-dimensional geometries can be extended to much tighter
confinements than previously thought. This is achieved by replacing the
scattering length by an energy-dependent scattering length which was already
introduced for the calculation of energy levels under 3D confinement. This
replacement accurately predicts the position of confinement-induced resonances
in strongly confined geometries.
},
doi = {10.1088/1367-2630/9/1/019},
url = {http://arxiv.org/abs/physics/0607140v2},
author = {Pascal Naidon and Eite Tiesinga and William F. Mitchell and Paul S. Julienne}
}
@article {1290,
title = {Multichannel quantum-defect theory for slow atomic collisions},
journal = {Physical Review A},
volume = {72},
year = {2005},
month = {2005/10/28},
abstract = { We present a multichannel quantum-defect theory for slow atomic collisions
that takes advantages of the analytic solutions for the long-range potential,
and both the energy and the angular-momentum insensitivities of the short-range
parameters. The theory provides an accurate and complete account of scattering
processes, including shape and Feshbach resonances, in terms of a few
parameters such as the singlet and the triplet scattering lengths. As an
example, results for $^{23}$Na-$^{23}$Na scattering are presented and compared
close-coupling calculations.
},
doi = {10.1103/PhysRevA.72.042719},
url = {http://arxiv.org/abs/physics/0508060v1},
author = {Bo Gao and Eite Tiesinga and Carl J. Williams and Paul S. Julienne}
}
@article {1297,
title = {Sodium Bose-Einstein Condensates in an Optical Lattice},
journal = {Physical Review A},
volume = {72},
year = {2005},
month = {2005/10/10},
abstract = { 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.
},
doi = {10.1103/PhysRevA.72.043604},
url = {http://arxiv.org/abs/cond-mat/0507288v1},
author = {K. Xu and Y. Liu and J. R. Abo-Shaeer and T. Mukaiyama and J. K. Chin and D. E. Miller and W. Ketterle and Kevin M. Jones and Eite Tiesinga}
}
@article {1275,
title = {Spontaneous dissociation of long-range Feshbach molecules},
journal = {Physical Review Letters},
volume = {94},
year = {2005},
month = {2005/1/18},
abstract = { 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$_2$.
},
doi = {10.1103/PhysRevLett.94.020402},
url = {http://arxiv.org/abs/cond-mat/0408387v2},
author = {Thorsten Koehler and Eite Tiesinga and Paul S. Julienne}
}
@article {1288,
title = {Adiabatic association of ultracold molecules via magnetic field tunable interactions
},
journal = {Journal of Physics B: Atomic, Molecular and Optical Physics},
volume = {37},
year = {2004},
month = {2004/09/14},
pages = {3457 - 3500},
abstract = { We consider in detail the situation of applying a time dependent external
magnetic field to a 87Rb atomic Bose-Einstein condensate held in a harmonic
trap, in order to adiabatically sweep the interatomic interactions across a
Feshbach resonance to produce diatomic molecules. To this end, we introduce a
minimal two-body Hamiltonian depending on just five measurable parameters of a
Feshbach resonance, which accurately determines all low energy binary
scattering observables, in particular, the molecular conversion efficiency of
just two atoms. Based on this description of the microscopic collision
phenomena, we use the many-body theory of T. Koehler and K. Burnett [Phys. Rev.
A 65, 033601 (2002)] to study the efficiency of the association of molecules in
a 87Rb Bose-Einstein condensate during a linear passage of the magnetic field
strength across the 100 mT Feshbach resonance. We explore different,
experimentally accessible, parameter regimes, and compare the predictions of
Landau-Zener, configuration interaction, and two level mean field calculations
with those of the microscopic many-body approach. Our comparative studies
reveal a remarkable insensitivity of the molecular conversion efficiency with
respect to both the details of the microscopic binary collision physics and the
coherent nature of the Bose-Einstein condensed gas, provided that the magnetic
field strength is varied linearly. We provide the reasons for this universality
of the molecular production achieved by linear ramps of the magnetic field
strength, and identify the Landau-Zener coefficient determined by F.H. Mies et
al. [Phys. Rev. A 61, 022721 (2000)] as the main parameter that controls the
efficiency.
},
doi = {10.1088/0953-4075/37/17/006},
url = {http://arxiv.org/abs/cond-mat/0312178v5},
author = {Krzysztof Goral and Thorsten Koehler and Simon A. Gardiner and Eite Tiesinga and Paul S. Julienne}
}
@article {1289,
title = {Ultracold collision properties of metastable alkaline-earth atoms},
journal = {Physical Review Letters},
volume = {90},
year = {2003},
month = {2003/2/13},
abstract = { Ultra-cold collisions of spin-polarized 24Mg,40Ca, and 88Sr in the metastable
3P2 excited state are investigated. We calculate the long-range interaction
potentials and estimate the scattering length and the collisional loss rate as
a function of magnetic field. The estimates are based on molecular potentials
between 3P2 alkaline-earth atoms obtained from ab initio atomic and molecular
structure calculations. The scattering lengths show resonance behavior due to
the appearance of a molecular bound state in a purely long-range interaction
potential and are positive for magnetic fields below 50 mT. A loss-rate model
shows that losses should be smallest near zero magnetic field and for fields
slightly larger than the resonance field, where the scattering length is also
positive.
},
doi = {10.1103/PhysRevLett.90.063002},
url = {http://arxiv.org/abs/physics/0210076v1},
author = {Andrei Derevianko and Sergey G. Porsev and Svetlana Kotochigova and Eite Tiesinga and Paul S. Julienne}
}
@article {1296,
title = {Ultracold Cs$_2$ Feshbach Spectroscopy},
year = {2003},
month = {2003/12/23},
abstract = { We have observed and located more than 60 magnetic field-induced Feshbach
resonances in ultracold collisions of ground-state $^{133}$Cs atoms. These
resonances are associated with molecular states with up to four units of
rotational angular momentum, and are detected through variations in the
elastic, inelastic, and radiative collision cross sections. These observations
allow us to greatly improve upon the interaction potentials between two cesium
atoms and to reproduce the positions of most resonances to accuracies better
than 0.5\%. Based on the relevant coupling scheme between the electron spin,
nuclear spin, and orbital angular momenta of the nuclei, quantum numbers and
energy structure of the molecular states beneath the dissociation continuum are
revealed. Finally, we predict the relevant collision properties for cesium
Bose-Einstein condensation experiments.
},
url = {http://arxiv.org/abs/cond-mat/0312613v2},
author = {Cheng Chin and Vladan Vuletic and Andrew J. Kerman and Steven Chu and Eite Tiesinga and Paul J. Leo and Carl J. Williams}
}