2,143 research outputs found
Multidimensional hyperspin machine
No full textFrom condensed matter to quantum chromodynamics, multidimensional spins are a
fundamental paradigm, with a pivotal role in combinatorial optimization and
machine learning. Machines formed by coupled parametric oscillators can
simulate spin models, but only for Ising or low-dimensional spins. Currently,
machines implementing arbitrary dimensions remain a challenge. Here, we
introduce and validate a hyperspin machine to simulate multidimensional
continuous spin models. We realize high-dimensional spins by pumping groups of
parametric oscillators, and study NP-hard graphs of hyperspins. The hyperspin
machine can interpolate between different dimensions by tuning the coupling
topology, a strategy that we call "dimensional annealing". When interpolating
between the XY and the Ising model, the dimensional annealing impressively
increases the success probability compared to conventional Ising simulators.
Hyperspin machines are a new computational model for combinatorial
optimization. They can be realized by off-the-shelf hardware for ultrafast,
large-scale applications in classical and quantum computing, condensed-matter
physics, and fundamental studies.Comment: 11 pages, 7 figures. This preprint version of the paper is a
pre-submission version, which has not undergone peer review. For the
published version, please see Nature Communications 13, 7248 (2022
Hyperscaling in the coherent hyperspin machine
Get PDFClassical or quantum physical systems can simulate the Ising Hamiltonian for
large-scale optimization and machine learning. However, devices such as quantum
annealers and coherent Ising machines suffer an exponential drop in the
probability of success in finite-size scaling. We show that by exploiting high
dimensional embedding of the Ising Hamiltonian and subsequent dimensional
annealing, the drop is counteracted by an exponential improvement in the
performance. Our analysis relies on extensive statistics of the convergence
dynamics by high-performance computing. We propose a realistic experimental
implementation of the new annealing device by off-the-shelf coherent Ising
machine technology. The hyperscaling heuristics can also be applied to other
quantum or classical Ising machines by engineering nonlinear gain, loss, and
non-local couplings.Comment: 6 pages, 4 figure
All-Optical Scalable Spatial Coherent Ising Machine
No full textNetworks of optical oscillators simulating coupled Ising spins have been recently proposed as a heuris-tic platform to solve hard optimization problems. These networks, called coherent Ising machines (CIMs), exploit the fact that the collective nonlinear dynamics of coupled oscillators can drive the system close to the global minimum of the classical Ising Hamiltonian, encoded in the coupling matrix of the network. To date, realizations of large-scale CIMs have been demonstrated using hybrid optical-electronic setups, where optical oscillators simulating different spins are subject to electronic feedback mechanisms emulat-ing their mutual interaction. While the optical evolution ensures an ultrafast computation, the electronic coupling represents a bottleneck that causes the computational time to severely depend on the system size. Here, we propose an all-optical scalable CIM with fully programmable coupling. Our setup consists of an optical parametric amplifier with a spatial light modulator (SLM) within the parametric cavity. The spin variables are encoded in the binary phases of the optical wave front of the signal beam at different spatial points, defined by the pixels of the SLM. We first discuss how different coupling topologies can be achieved by different configurations of the SLM, and then benchmark our setup with a numerical sim-ulation that mimics the dynamics of the proposed machine. In our proposal, both the spin dynamics and the coupling are fully performed in parallel, paving the way towards the realization of size-independent ultrafast optical hardware for large-scale computation purposes
Postal de Claudio Vivas a Maruja Vieira, junio 23 de 1955
No full textPostal de Claudio Vivas a Maruja Vieira, felicitándola por el reconocimiento que le fue otorgado a la autora de poemasPostcard from Claudio Vivas to Maruja Vieira, congratulating her for the recognition given to the author of poems.Publicación, fondo Maruja Vieira, carpeta 1, folio
Automated Activity Recognition in Clinical Documents
No full textWe describe a first experiment on activity
identification, and more in general, on
the identification and extraction of computer
interpreted guideline components
from clinical documents, based on clinical
entity recognition techniques (viz., activities,
and their actors and consumed artifacts).
We rely on MetaMap and the
UMLS Metathesaurus to provide lexical
information and study the impact of clinical
document syntax and semantics on activity
recognition precision
Efficacia del beclometasone dipropionato in un caso di colite plasmacellulare.
No full textDescrizione di un caso clinico di colite plasmacellulare e del trattamento utilizzato con revisione dei possibili trattamenti alternativi
The VeriCliG Project: Extraction of Computer Interpretable Guidelines via Syntactic and Semantic Annotation
No full textWe consider the problem of extracting formal process representations of the therapies defined by
clinical guidelines, viz., computer interpretable guidelines (CIGs), based on UMLS and semantic
and syntactic annotation. CIGs enable the application of formal methods (such as model checking,
verification, conformance assessment) to the clinical domain. We argue that, while minimally structured, correspondences among clinical guideline syntax and discourse relations and clinical process
constructs should however be exploited to successfully extract CIGs. We review work on current
clinical syntactic and semantic annotation, pinpointing their limitations, and discuss a CIG extraction methodology based on recent efforts on business process modelling notation (BPMN) model
extraction from natural language tex
ENERGY DIFFUSION IN DISORDERED ELECTRONIC SYSTEMS NEAR THE ANDERSON TRANSITION
No full textThe problem of heat diffusion for a noninteracting electron gas scattered by random impurities is formulated in terms of a frequency- and wave-vector-dependent grand canonical energy-energy (heat-heat) correlation function KK(q;). Consistently with a Ward identity associated with the continuity equation for heat diffusion, we show that the heat-heat correlation function has the same critical diffusive behavior of the density-density correlation function. This result enables us, in particular, to predict that the electrical conductivity and the thermal conductivity (times the inverse temperature) of metals scale to zero in the same way near the Anderson transition. © 1987 The American Physical Society
Endoscopic ultrasound-guided jejuno-jejunal anastomosis for malignant outlet obstruction after total gastrectomy
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