91 research outputs found
Group Theoretical Formulation of Quantum Partial Search Algorithm
Searching and sorting used as a subroutine in many important algorithms.
Quantum algorithm can find a target item in a database faster than any
classical algorithm. One can trade accuracy for speed and find a part of the
database (a block) containing the target item even faster, this is partial
search. An example is the following: exact address of the target item is given
by a sequence of many bits, but we need to know only some of them. More
generally partial search considers the following problem: a database is
separated into several blocks. We want to find a block with the target item,
not the target item itself. In this paper we reformulate quantum partial search
algorithm in terms of group theory.Comment: 12 page
Spectrum of Low-Lying Excitations in a Supersymmetric Extended Hubbard Model
We continue the study of the -supersymmetric extension of the Hubbard
model in one dimension. We determine the excitation spectrum at zero
temperature even in the sectors where the ground states are
-descendants of Bethe states. The excitations include spinons, holons,
electrons, localons (local electrons pairs, moving coherently through the
lattice) and their bound states. The spectra are found to be very different for
repulsive and attractive on-site interaction. We also study the thermodynamics
of the model.Comment: 37 pages, uuencoded compressed postscript fil
Integro-Difference Equation for a correlation function of the spin- Heisenberg XXZ chain
We consider the Ferromagnetic-String-Formation-Probability correlation
function (FSFP) for the spin- Heisenberg XXZ chain. We construct a
completely integrable system of integro-difference equations (IDE), which has
the FSFP as a -function. We derive the associated Riemann-Hilbert problem
and obtain the large distance asymptotics of the FSFP correlator in some
limiting cases.Comment: 14 pages, latex+epsf, 1 figur
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