319 research outputs found
Automatic grid construction for few-body quantum mechanical calculations
An algorithm for generating optimal nonuniform grids for solving the two-body
Schr\"odinger equation is developed and implemented. The shape of the grid is
optimized to accurately reproduce the low-energy part of the spectrum of the
Schr\"odinger operator. Grids constructed this way are applicable to more
complex few-body systems where the number of grid points is a critical
limitation to numerical accuracy. The utility of the grid generation for
improving few-body calculations is illustrated through an application to bound
states of He trimers
Limits on Universality in Ultracold Three-Boson Recombination
The recombination rate for three identical bosons has been calculated to test
the limits of its universal behavior. It has been obtained for several
different collision energies and scattering lengths (a) up to 10^5 a.u., giving
rates that vary over 15 orders of magnitude. We find that universal behavior is
limited to the threshold region characterized by E lesssim
hbar^2/(2mu_{12}a^2), where E is the total energy and mu_{12} is the two-body
reduced mass. The analytically predicted infinite series of resonance peaks and
interference minima is truncated to no more than three of each for typical
experimental parameters.Comment: 4 pages, 3 figure
Magnons and electromagnons in a spin-lattice-coupled frustrated magnet CuFeO2 as seen via inelastic neutron scattering
We have investigated spin-wave excitations in a four-sublattice (4SL)
magnetic ground state of a frustrated magnet CuFeO2, in which `electromagnon'
(electric-field-active magnon) excitation has been discovered by recent
terahertz time-domain spectroscopy [Seki et al. Phys. Rev. Lett. 105 097207
(2010)]. In previous study, we have identified two spin-wave branches in the
4SL phase by means of inelastic neutron scattering measurements under applied
uniaxial pressure. [T. Nakajima et al. J. Phys. Soc. Jpn. 80 014714 (2011) ] In
the present study, we have performed high-energy-resolution inelastic neutron
scattering measurements in the 4SL phase, resolving fine structures of the
lower-energy spin-wave branch near the zone center. Taking account of the
spin-driven lattice distortions in the 4SL phase, we have developed a model
Hamiltonian to describe the spin-wave excitations. The determined Hamiltonian
parameters have successfully reproduced the spin-wave dispersion relations and
intensity maps obtained in the inelastic neutron scattering measurements. The
results of the spin-wave analysis have also revealed physical pictures of the
magnon and electromagnon modes in the 4SL phase, suggesting that collinear and
noncollinear characters of the two spin-wave modes are the keys to understand
the dynamical coupling between the spins and electric dipole moments in this
system.Comment: 8 pages, 6 figure
Tuning p-wave interactions in an ultracold Fermi gas of atoms
We have measured a p-wave Feshbach resonance in a single-component, ultracold
Fermi gas of potassium atoms. We have used this resonance to enhance the
normally suppressed p-wave collision cross-section to values larger than the
background s-wave cross-section between potassium atoms in different
spin-states. In addition to the modification of two-body elastic processes, the
resonance dramatically enhances three-body inelastic collisional loss.Comment: 4 pages, 5 figure
Adiabatic hyperspherical study of triatomic helium systems
The 4He3 system is studied using the adiabatic hyperspherical representation.
We adopt the current state-of-the-art helium interaction potential including
retardation and the nonadditive three-body term, to calculate all low-energy
properties of the triatomic 4He system. The bound state energies of the 4He
trimer are computed as well as the 4He+4He2 elastic scattering cross sections,
the three-body recombination and collision induced dissociation rates at finite
temperatures. We also treat the system that consists of two 4He and one 3He
atoms, and compute the spectrum of the isotopic trimer 4He2 3He, the 3He+4He2
elastic scattering cross sections, the rates for three-body recombination and
the collision induced dissociation rate at finite temperatures. The effects of
retardation and the nonadditive three-body term are investigated. Retardation
is found to be significant in some cases, while the three-body term plays only
a minor role for these systems.Comment: 24 pages 6 figures Submitted to Physical Review
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