Publications by authors named "H G Katzgraber"

Optimization plays a significant role in many areas of science and technology. Most of the industrial optimization problems have inordinately complex structures that render finding their global minima a daunting task. Therefore, designing heuristics that can efficiently solve such problems is of utmost importance.

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Magnetic resonance fingerprinting (MRF) is a method to extract quantitative tissue properties such as [Formula: see text] and [Formula: see text] relaxation rates from arbitrary pulse sequences using conventional MRI hardware. MRF pulse sequences have thousands of tunable parameters, which can be chosen to maximize precision and minimize scan time. Here, we perform de novo automated design of MRF pulse sequences by applying physics-inspired optimization heuristics.

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Article Synopsis
  • The Wishart planted ensemble is a type of zero-field Ising model that allows control over algorithmic difficulty and has a specified ground state, stemming from a method for creating random integer programming challenges with unique statistical traits.
  • This model involves only 2-spin interactions with a coupler matrix based on a Wishart distribution and shows a classical first-order phase transition influenced by temperature, demonstrating complex properties linked to finding its ground state.
  • Detailed analyses, including the derivation of thermodynamic properties and Monte Carlo simulations, highlight the model’s varying algorithmic hardness, with distinct “easy-hard-easy” patterns and an increase in problem difficulty as system size grows.
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Quantum annealing is a computing paradigm that has the ambitious goal of efficiently solving large-scale combinatorial optimization problems of practical importance. However, many challenges have yet to be overcome before this goal can be reached. This perspectives article first gives a brief introduction to the concept of quantum annealing, and then highlights new pathways that may clear the way towards feasible and large scale quantum annealing.

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We investigate the computational hardness of spin-glass instances on a square lattice, generated via a recently introduced tunable and scalable approach for planting solutions. The method relies on partitioning the problem graph into edge-disjoint subgraphs and planting frustrated, elementary subproblems that share a common local ground state, which guarantees that the ground state of the entire problem is known a priori. Using population annealing Monte Carlo, we compare the typical hardness of problem classes over a large region of the multidimensional tuning parameter space.

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