24,998 research outputs found
Best-case performance of quantum annealers on native spin-glass benchmarks: How chaos can affect success probabilities
Recent tests performed on the D-Wave Two quantum annealer have revealed no
clear evidence of speedup over conventional silicon-based technologies. Here,
we present results from classical parallel-tempering Monte Carlo simulations
combined with isoenergetic cluster moves of the archetypal benchmark problem-an
Ising spin glass-on the native chip topology. Using realistic uncorrelated
noise models for the D-Wave Two quantum annealer, we study the best-case
resilience, i.e., the probability that the ground-state configuration is not
affected by random fields and random-bond fluctuations found on the chip. We
thus compute classical upper-bound success probabilities for different types of
disorder used in the benchmarks and predict that an increase in the number of
qubits will require either error correction schemes or a drastic reduction of
the intrinsic noise found in these devices. We outline strategies to develop
robust, as well as hard benchmarks for quantum annealing devices, as well as
any other computing paradigm affected by noise.Comment: 8 pages, 5 figure
Thermodynamic Theory of Weakly Excited Granular Materials
We present a thermodynamic theory of weakly excited two-dimensional granular
systems from the view point of elementary excitations of spinless Fermion
systems. We introduce a global temperature T that is associated with the
acceleration amplitude \Gamma in a vibrating bed. We show that the
configurational statistics of weakly excited granular materials in a vibrating
bed obey the Fermi statistics.Comment: 12 pages, 1 figure, To Appear in Phys. Rev. Lett. April, 199
Resource Letter TF-1: Turbulence in Fluids
This Resource Letter provides a guide to the literature on fully developed
turbulence in fluids. It is restricted to mechanically driven turbulence in an
incompressible fluid described by the Navier-Stokes equations of hydrodynamics,
and places greatest emphasis on fundamental physical questions. Journal
articles and books are cited for the following topics: The Navier-Stokes
equations, qualitative aspects of turbulence, the 1941 Kolmogorov theory,
intermittency and small scale structure, time correlations and pressure; with
brief mention of two-dimensional turbulence, passive scalars in turbulence, and
the turbulent boundary layer,Comment: 38 pages LaTeX, no figures. To appear in American Journal of Physic
Soliton crystals in Kerr resonators
Strongly interacting solitons confined to an optical resonator would offer
unique capabilities for experiments in communication, computation, and sensing
with light. Here we report on the discovery of soliton crystals in monolithic
Kerr microresonators-spontaneously and collectively ordered ensembles of
co-propagating solitons whose interactions discretize their allowed temporal
separations. We unambiguously identify and characterize soliton crystals
through analysis of their 'fingerprint' optical spectra, which arise from
spectral interference between the solitons. We identify a rich space of soliton
crystals exhibiting crystallographic defects, and time-domain measurements
directly confirm our inference of their crystal structure. The crystallization
we observe is explained by long-range soliton interactions mediated by
resonator mode degeneracies, and we probe the qualitative difference between
soliton crystals and a soliton liquid that forms in the absence of these
interactions. Our work explores the rich physics of monolithic Kerr resonators
in a new regime of dense soliton occupation and offers a way to greatly
increase the efficiency of Kerr combs; further, the extreme degeneracy of the
configuration space of soliton crystals suggests an implementation for a robust
on-chip optical buffer
Chimera states: Coexistence of coherence and incoherence in networks of coupled oscillators
A chimera state is a spatio-temporal pattern in a network of identical
coupled oscillators in which synchronous and asynchronous oscillation coexist.
This state of broken symmetry, which usually coexists with a stable spatially
symmetric state, has intrigued the nonlinear dynamics community since its
discovery in the early 2000s. Recent experiments have led to increasing
interest in the origin and dynamics of these states. Here we review the history
of research on chimera states and highlight major advances in understanding
their behaviour.Comment: 26 pages, 3 figure
Bichromatically driven double well: parametric perspective of the strong-field control landscape reveals the influence of chaotic states
The aim of this work is to understand the influence of chaotic states in
control problems involving strong fields. Towards this end, we numerically
construct and study the strong field control landscape of a bichromatically
driven double well. A novel measure based on correlating the overlap
intensities between Floquet states and an initial phase space coherent state
with the parametric motion of the quasienergies is used to construct and
interpret the landscape features. "Walls" of no control, robust under
variations of the relative phase between the fields, are seen on the control
landscape and associated with multilevel interactions involving chaotic Floquet
states.Comment: 9 pages and 6 figures. Rewritten and expanded version of
arXiv:0707.4547 [nlin.CD]. Accepted for publication in J. Chem. Phys. (2008
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