3,357,858 research outputs found
Multi-output programmable quantum processor
By combining telecloning and programmable quantum gate array presented by
Nielsen and Chuang [Phys.Rev.Lett. 79 :321(1997)], we propose a programmable
quantum processor which can be programmed to implement restricted set of
operations with several identical data outputs. The outputs are
approximately-transformed versions of input data. The processor successes with
certain probability.Comment: 5 pages and 2 PDF figure
Instabilities at [110] Surfaces of d_{x^2-y^2} Superconductors
We compare different scenarios for the low temperature splitting of the
zero-energy peak in the local density of states at (110) surfaces of
d_{x^2-y^2}-wave superconductors, observed by Covington et al.
(Phys.Rev.Lett.79 (1997), 277). Using a tight binding model in the
Bogolyubov-de Gennes treatment we find a surface phase transition towards a
time-reversal symmetry breaking surface state carrying spontaneous currents and
an s+id-wave state. Alternatively, we show that electron correlation leads to a
surface phase transition towards a magnetic state corresponding to a local spin
density wave state.Comment: 4 pages, 5 figure
Comment on "Quenches in quantum many-body systems: One-dimensional Bose-Hubbard model reexamined" [arXiv:0810.3720]
In a recent paper Roux [Phys. Rev. A 79, 021608(R) (2009), arXiv:0810.3720]
argued that thermalization in a Bose-Hubbard system, after a quench, follows
from the approximate Boltzmann distribution of the overlap between the initial
state and the eigenstates of the final Hamiltonian. We show here that the
distribution of the overlaps is in general not related to the canonical (or
microcanonical) distribution and, hence, it cannot explain why thermalization
occurs in quantum systems.Comment: 2 pages, 1 figure, as publishe
Superconductivity in SrFe2As2 with Pt Doping
We have synthesized polycrystalline samples of Pt-substituted SrFe2As2 and
measured the temperature dependence of magnetization and electrical
resistivity. We have observed the superconducting transition at Tc = 17 K with
the maximum shielding volume fraction at x = 0.125 in Sr(Fe1-xPtx)2As2. It is
found that the maximum Tc depends on the substituted element, so it is
important to substitute various elements to explore new iron-based
superconductors with higher Tc.Comment: 2 pages, 1 figure, to appear in J. Phys. Soc. Jpn. Vol. 79 No. 9
(2010
Process chain approach to high-order perturbation calculus for quantum lattice models
A method based on Rayleigh-Schroedinger perturbation theory is developed that
allows to obtain high-order series expansions for ground-state properties of
quantum lattice models. The approach is capable of treating both lattice
geometries of large spatial dimensionalities d and on-site degrees of freedom
with large state space dimensionalities. It has recently been used to
accurately compute the zero-temperature phase diagram of the Bose-Hubbard model
on a hypercubic lattice, up to arbitrary large filling and for d=2, 3 and
greater [Teichmann et al., Phys. Rev. B 79, 100503(R) (2009)].Comment: 11 pages, 6 figure
A new numerical method for obtaining gluon distribution functions , from the proton structure function
An exact expression for the leading-order (LO) gluon distribution function
from the DGLAP evolution equation for the proton structure
function for deep inelastic scattering has
recently been obtained [M. M. Block, L. Durand and D. W. McKay, Phys. Rev.
D{\bf 79}, 014031, (2009)] for massless quarks, using Laplace transformation
techniques. Here, we develop a fast and accurate numerical inverse Laplace
transformation algorithm, required to invert the Laplace transforms needed to
evaluate , and compare it to the exact solution. We obtain accuracies
of less than 1 part in 1000 over the entire and spectrum. Since no
analytic Laplace inversion is possible for next-to-leading order (NLO) and
higher orders, this numerical algorithm will enable one to obtain accurate NLO
(and NNLO) gluon distributions, using only experimental measurements of
.Comment: 9 pages, 2 figure
- …