Bulletin of the American Physical Society
38th Annual Meeting of the Division of Atomic, Molecular, and Optical Physics
Volume 52, Number 7
Tuesday–Saturday, June 5–9, 2007; Calgary, Alberta, Canada
Session J2: Focus Session: Quantum Monte Carlo Calculations and Other Numerical Simulations of Cold Gases |
Hide Abstracts |
Chair: D. Blume, Washington State University Room: TELUS Convention Centre Macleod D |
Thursday, June 7, 2007 1:30PM - 2:06PM |
J2.00001: Quantum Monte Carlo (QMC) Methods for strongly correlated Bose and Fermi Systems Invited Speaker: I will give two examples where the fluctuations probed by QMC highlight the novel physics of strongly correlated systems. In the first example of bosons in optical lattices, we find in addition to the sound mode, evidence for extra gapped modes in the correlated superfluid phase [1]. We also calculate the effect of thermal and quantum fluctuations, including vortices, on the superfluid density and condensate fraction and compare with recent experiments in optical lattices [2]. In the second example, we calculate the pairing and superfluid properties of a dilute gas of fermions in 3-dimensions with attractive interactions tuned to the unitarity point [3]. From the growth of the density correlations for unequal spins, we identify the pseudogap crossover temperature scale $T^\ast \approx 0.7E_F $ below which pairing correlations develop. The pseudogap phase is characterised by the temperature dependence of spin susceptibility and compressibility. We estimate the critical temperature for condensation $T_c \approx 0.24E_F$ from a finite size scaling analysis of the superfluid density. \newline \newline [1] C. Menotti and N. Trivedi, preprint. \newline [2] Y. Kato, N. Kawashima, and N. Trivedi, preprint. \newline [3] V. Akkineni, N. Trivedi, D.M. Ceperley, cond-mat/0608154. [Preview Abstract] |
Thursday, June 7, 2007 2:06PM - 2:18PM |
J2.00002: Variance minimization variational Monte Carlo method Bo Gao, Imran Khan We present a variational Monte Carlo (VMC) method that works equally well for the ground and the excited states of a quantum system. The method is based on the minimization of the variance of energy, as opposed to the energy itself in standard methods. As a test, it is applied to the investigation of the universal spectrum at the van der Waals length scale for two identical Bose atoms in a symmetric harmonic trap, with results compared to the basically exact results obtained from a multiscale quantum-defect theory\footnote{Y. Chen and B. Gao, cond-mat/0701384.}. Results for trapped few-atom systems\footnote{I. Khan and B. Gao, Phys. Rev. A \textbf{73}, 063619 (2006).} will also be presented. [Preview Abstract] |
Thursday, June 7, 2007 2:18PM - 2:30PM |
J2.00003: Thermodynamic properties of the three-dimensional Bose-Hubbard model Barbara Capogrosso-Sansone, Evgeny Kozik, Nikolay Prokof'ev, Boris Svistunov We have studied the thermodynamics of the three dimensional Bose-Hubbard model by means of exact quantum Monte Carlo simulations. We present accurate thermodynamic curves, including those for entropy and specific heat, for the homogeneous and inhomogeneous system. We also present numerical data for the on site number statistics and compare numerical curves to experimental ones, using temperature as the only free parameter. Our data can serve as a basis for accurate experimental thermometry and a guide for appropriate initial conditions if one attempts to use interacting bosons in quantum information processing. [Preview Abstract] |
Thursday, June 7, 2007 2:30PM - 3:06PM |
J2.00004: 2D Self-Assembled Crystals with Polar Molecules Invited Speaker: We discuss the possibility to control the strength and design the shape of the long-range part of the interaction potentials of bosonic polar molecules using static and microwave fields. The dressing of rotational excitations combined with low dimensional trapping provides novel tools to engineer strongly correlated quantum phases, which we study utilizing recently developed quantum Monte Carlo techniques. As an example, we show that intermolecular dipole-dipole interactions can drive the system from a superfluid to a \textit{self-assembled} crystalline phase, which has never been observed so far with cold molecular or atomic gases. [Preview Abstract] |
Thursday, June 7, 2007 3:06PM - 3:18PM |
J2.00005: A Parallel Time-Propagation Solver for the Non-Linear Schroedinger Equation. Nicolai Nygaard, Tapio Simula, Barry I. Schneider We describe a powerful numerical method for solving the time-dependent non-linear Schr\"{o}dinger equation. Our method is based on the finite-element discrete variable representation. The time-propagation is facilitated either by the Lanczos-Arnoldi method or by split-operator formulas of different orders. The ground-state solution is found by propagation in imaginary time using an adaptive time stepping algorithm, and the absolute convergence of the propagation is faithfully characterized by a positive-definite error norm. Parallelization of this method is transparent, and we have utilized an MPI implementation demonstrating linear scaling of wall-clock computation time with the number of processors used. [Preview Abstract] |
Thursday, June 7, 2007 3:18PM - 3:30PM |
J2.00006: Two-component Fermi gases with unequal masses in a harmonic trap. Javier von Stecher, Doerte Blume, Chris H. Greene Dilute two-component Fermi gases with equal masses and tunable interspecies scattering length have been realized experimentally. Motivated by experimental efforts to simultaneously cool and trap two different fermionic species, we theoretically investigate the behaviors of trapped two-component Fermi gases with varying mass ratio in the crossover regime, including infinitely strongly-interacting systems. We determine the energy spectrum of the four-body system using essentially exact basis set diagonalization techniques and using the fixed-node diffusion Monte Carlo method. By comparing the energies obtained by these two approaches, we assess the quality of the nodal surface used in the Monte Carlo calculations. Our results allow, for example, for the determination of the dimer-dimer scattering length. Finally, we present Monte Carlo results for larger systems. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700