30 research outputs found
Pseudo-time Schroedinger equation with absorbing potential for quantum scattering calculations
The Schroedinger equation with an energy-dependent complex absorbing
potential, associated with a scattering system, can be reduced for a special
choice of the energy-dependence to a harmonic inversion problem of a discrete
pseudo-time correlation function. An efficient formula for Green's function
matrix elements is also derived. Since the exact propagation up to time 2t can
be done with only t real matrix-vector products, this gives an unprecedently
efficient scheme for accurate calculations of quantum spectra for possibly very
large systems.Comment: 9 page
Time Asymmetric Quantum Physics
Mathematical and phenomenological arguments in favor of asymmetric time
evolution of micro-physical states are presented.Comment: Tex file with 2 figure
The Hyperspherical Four-Fermion Problem
The problem of a few interacting fermions in quantum physics has sparked
intense interest, particularly in recent years owing to connections with the
behavior of superconductors, fermionic superfluids, and finite nuclei. This
review addresses recent developments in the theoretical description of four
fermions having finite-range interactions, stressing insights that have emerged
from a hyperspherical coordinate perspective. The subject is complicated, so we
have included many detailed formulas that will hopefully make these methods
accessible to others interested in using them. The universality regime, where
the dominant length scale in the problem is the two-body scattering length, is
particularly stressed, including its implications for the famous BCS-BEC
crossover problem Derivations and relevant formulas are also included for the
calculation of challenging few-body processes such as recombination.Comment: 66 pages, 33 figure
Measurement and laser control of attosecond charge migration in ionized iodoacetylene
peer reviewedThe ultrafast motion of electrons and holes after light-matter interaction is fundamental to a broad range of chemical and biophysical processes. We advanced high-harmonic spectroscopy to resolve spatially and temporally the migration of an electron hole immediately after ionization of iodoacetylene while simultaneously demonstrating extensive control over the process. A multidimensional approach, based on the measurement and accurate theoretical description of both even and odd harmonic orders, enabled us to reconstruct both quantum amplitudes and phases of the electronic states with a resolution of ~100 attoseconds. We separately reconstructed quasi–field-free and laser-controlled charge migration as a function of the spatial orientation of the molecule and determined the shape of the hole created by ionization. Our technique opens the prospect of laser control over electronic primary processes.Control of attosecond dynamic