3,118 research outputs found
Quantum Approximation II. Sobolev Embeddings
A basic problem of approximation theory, the approximation of functions from
the Sobolev space W_p^r([0,1]^d) in the norm of L_q([0,1]^d), is considered
from the point of view of quantum computation. We determine the quantum query
complexity of this problem (up to logarithmic factors). It turns out that in
certain regions of the domain of parameters p,q,r,d quantum computation can
reach a speedup of roughly squaring the rate of convergence of classical
deterministic or randomized approximation methods. There are other regions were
the best possible rates coincide for all three settings.Comment: 23 pages, paper submitted to the Journal of Complexit
On a Problem in Quantum Summation
We consider the computation of the mean of sequences in the quantum model of
computation. We determine the query complexity in the case of sequences which
satisfy a -summability condition for . This settles a problem left
open in Heinrich (2001).Comment: 21 pages, paper submitted to the Journal of Complexit
Quantum Integration in Sobolev Classes
We study high dimensional integration in the quantum model of computation. We
develop quantum algorithms for integration of functions from Sobolev classes
and analyze their convergence rates. We also prove lower
bounds which show that the proposed algorithms are, in many cases, optimal
within the setting of quantum computing. This extends recent results of Novak
on integration of functions from H\"older classes.Comment: Paper submitted to the Journal of Complexity. 28 page
Controlling the Hole Alignment in Neon via the - Fano Resonance
We study the state-resolved production of neon ion after resonant
photoionization of Ne via the - Fano resonance. We find that by tuning
the photon energy across the Fano resonance a surprisingly high control over
the alignment of the final hole along the polarization direction can be
achieved. In this way hole alignments can be created that are otherwise very
hard to achieve. The mechanism responsible for this hole alignment is the
destructive interference of the direct and indirect (via the autoionizing
state) ionization pathways of . By changing the photon energy
the strength of the interference varies and -hole alignments with ratios up
to 19:1 between and holes can be created: an effect
normally only encountered in tunnel ionization using strong-field IR pulses.
Including spin-orbit interaction does not change the qualitative feature and
leads only to a reduction in the alignment by . Our study is based on a
time-dependent configuration-interaction singles (TDCIS) approach which solves
the multichannel time-dependent Schr\"odinger equation.Comment: 7 pages, 4 figure
Randomized Complexity of Parametric Integration and the Role of Adaption I. Finite Dimensional Case
We study the randomized -th minimal errors (and hence the complexity) of
vector valued mean computation, which is the discrete version of parametric
integration. The results of the present paper form the basis for the complexity
analysis of parametric integration in Sobolev spaces, which will be presented
in Part 2. Altogether this extends previous results of Heinrich and Sindambiwe
(J.\ Complexity, 15 (1999), 317--341) and Wiegand (Shaker Verlag, 2006).
Moreover, a basic problem of Information-Based Complexity on the power of
adaption for linear problems in the randomized setting is solved.Comment: 30 page
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