P-dit Probabilistic Ising Machine for Solving the Quadratic Assignment Problem

Fuente: arXiv
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Main Authors: Duffee, Christian, Burling-Smith, Chadbourne M., Athas, Jordan, Grimaldi, Andrea, Finocchio, Giovanni, Wei, Ermin, Amiri, Pedram Khalili
Format: Preprint
Published: 2026
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author Duffee, Christian
Burling-Smith, Chadbourne M.
Athas, Jordan
Grimaldi, Andrea
Finocchio, Giovanni
Wei, Ermin
Amiri, Pedram Khalili
author_facet Duffee, Christian
Burling-Smith, Chadbourne M.
Athas, Jordan
Grimaldi, Andrea
Finocchio, Giovanni
Wei, Ermin
Amiri, Pedram Khalili
contents Combinatorial optimization problems represent a wide range of real-world scenarios where complicated interactions make it difficult to find the best solution. One example is the quadratic assignment problem (QAP), which involves determining the optimal placement of facilities at set locations which minimizes the products of material flow and facility distance. This representation is descriptive of many real-world scenarios, including the aggregate transportation costs of a supply chain. In this work, a probabilistic Ising machine (PIM) approach is implemented using probabilistic d-dimensional variables (p-dits), which are generalized, multi-state and multi-dimensional extensions to probabilistic bits (p-bits). Each p-dit corresponds to a location and stochastically oscillates between facility assignments based on the influence of the other p-dits. We show that with the same runtime and CPU, the PIM finds the best-known solution on 95% of considered instances from the QAP Library dataset, compared to just 36% for the standard Gurobi solver. For the unique largest problem in the library, a 2 to 3 order-of-magnitude decrease is observed in the time needed to reach specific solution qualities. We also show parallelization of our PIM through GPU implementations. A comparison to state-of-the-art QAP solver algorithms shows that they are consistently outperformed by both CPU and GPU implementations of the p-dit Ising machine.
format Preprint
id arxiv_https___arxiv_org_abs_2605_24408
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle P-dit Probabilistic Ising Machine for Solving the Quadratic Assignment Problem
Duffee, Christian
Burling-Smith, Chadbourne M.
Athas, Jordan
Grimaldi, Andrea
Finocchio, Giovanni
Wei, Ermin
Amiri, Pedram Khalili
Applied Physics
Combinatorial optimization problems represent a wide range of real-world scenarios where complicated interactions make it difficult to find the best solution. One example is the quadratic assignment problem (QAP), which involves determining the optimal placement of facilities at set locations which minimizes the products of material flow and facility distance. This representation is descriptive of many real-world scenarios, including the aggregate transportation costs of a supply chain. In this work, a probabilistic Ising machine (PIM) approach is implemented using probabilistic d-dimensional variables (p-dits), which are generalized, multi-state and multi-dimensional extensions to probabilistic bits (p-bits). Each p-dit corresponds to a location and stochastically oscillates between facility assignments based on the influence of the other p-dits. We show that with the same runtime and CPU, the PIM finds the best-known solution on 95% of considered instances from the QAP Library dataset, compared to just 36% for the standard Gurobi solver. For the unique largest problem in the library, a 2 to 3 order-of-magnitude decrease is observed in the time needed to reach specific solution qualities. We also show parallelization of our PIM through GPU implementations. A comparison to state-of-the-art QAP solver algorithms shows that they are consistently outperformed by both CPU and GPU implementations of the p-dit Ising machine.
title P-dit Probabilistic Ising Machine for Solving the Quadratic Assignment Problem
topic Applied Physics
url https://arxiv.org/abs/2605.24408