44 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
Ultra-low energy elastic scattering in a system of three He atoms
Differential Faddeev equations in total angular momentum representation are
used for the first time to investigate ultra-low energy elastic scattering of a
helium atom on a helium dimer. Six potential models of interatomic interaction
are investigated. The results improve and extend the Faddeev equations based
results known in literature. The employed method can be applied to
investigation of different elastic and inelastic processes in three- and
four-atomic weakly bounded systems below three-body threshold.Comment: 13 pages, 4 tables, 2 figures, elsar
Unitary theory of laser Carrier-Envelope Phase effects
We consider a quantum state interacting with a short intense linearly
polarized laser pulse. Using the two-dimensional time representation and
Floquet picture we establish a straightforward connection between the laser
carrier-envelope phase (CEP) and the wave function. This connection is revealed
as a unitary transformation in the space of Floquet components. It allows any
CEP effect to be interpreted as an interference between the components and to
put limits on using the CEP in coherent control. A 2-level system is used to
illustrate the theory. On this example we demonstrate strong intensity
sensitivity of the CEP effects and predict an effect for pulses much longer
than the oscillation period of the carrier.Comment: 13 pages, 4 figure
Solution of three-dimensional Faddeev equations: ultracold Helium trimer calculations with a public quantum three-body code
Abstract. We present an illustration of using a quantum three-body code being prepared for public release. The code is based on iterative solving of the three-dimensional Faddeev equations. The code is easy to use and allows users to perform highly-accurate calculations of quantum three-body systems. The previously known results for He 3 ground state are well reproduced by the code
Resonance phenomena in ultracold dipole-dipole scattering
Elastic scattering resonances occurring in ultracold collisions of either
bosonic or fermionic polar molecules are investigated. The Born-Oppenheimer
adiabatic representation of the two-bodydynamics provides both a qualitative
classification scheme and a quantitative WKB quantization condition that
predicts several sequences of resonant states. It is found that the
near-threshold energy dependence of ultracold collision cross sections varies
significantly with the particle exchange symmetry, with bosonic systems showing
much smoother energy variations than their fermionic counterparts. Resonant
variations of the angular distributions in ultracold collisions are also
described.Comment: 19 pages, 6 figures, revtex4, submitted to J. Phys.