Solving the Max-Flow Problem on a Quantum Annealing Computer

This article addresses the question of implementing a maximum flow algorithm on directed graphs in a formulation suitable for a quantum annealing computer. Three distinct approaches are presented. In all three cases, the flow problem is formulated as a quadratic unconstrained binary optimization (QU...

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Main Authors: Thomas Krauss, Joey McCollum, Chapman Pendery, Sierra Litwin, Alan J. Michaels
Format: Article
Language:English
Published: IEEE 2020-01-01
Series:IEEE Transactions on Quantum Engineering
Subjects:
Online Access:https://ieeexplore.ieee.org/document/9224181/
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author Thomas Krauss
Joey McCollum
Chapman Pendery
Sierra Litwin
Alan J. Michaels
author_facet Thomas Krauss
Joey McCollum
Chapman Pendery
Sierra Litwin
Alan J. Michaels
author_sort Thomas Krauss
collection DOAJ
description This article addresses the question of implementing a maximum flow algorithm on directed graphs in a formulation suitable for a quantum annealing computer. Three distinct approaches are presented. In all three cases, the flow problem is formulated as a quadratic unconstrained binary optimization (QUBO) problem amenable to quantum annealing. The first implementation augments a graph with integral edge capacities into a multigraph with unit-capacity edges and encodes the fundamental objective and constraints of the maximum flow problem using a number of qubits equal to the total capacity of the graph $\sum _i{c_i}$. The second implementation, which encodes flows through edges using a binary representation, reduces the required number of qubits to $\mathcal {O}(|E| \log C_{\max })$, where $|E|$ and $C_{\max }$ denote the number of edges and maximum edge capacity of the graph, respectively. The third implementation adapts the dual minimum cut formulation and encodes the problem instance using $|V|$ qubits, where $|V|$ is the number of vertices in the graph. Scaling factors for penalty terms and coupling matrix construction times are made explicit in this article.
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spelling doaj.art-3816304de68c4d388bdaf672241e7cbc2022-12-21T20:37:05ZengIEEEIEEE Transactions on Quantum Engineering2689-18082020-01-01111010.1109/TQE.2020.30310859224181Solving the Max-Flow Problem on a Quantum Annealing ComputerThomas Krauss0https://orcid.org/0000-0001-8040-8046Joey McCollum1https://orcid.org/0000-0002-5647-0365Chapman Pendery2Sierra Litwin3Alan J. Michaels4Ted and Karyn Hume Center for National Security and Technology, Virginia Polytechnic Institute and State University, Blacksburg, VA, USATed and Karyn Hume Center for National Security and Technology, Virginia Polytechnic Institute and State University, Blacksburg, VA, USATed and Karyn Hume Center for National Security and Technology, Virginia Polytechnic Institute and State University, Blacksburg, VA, USATed and Karyn Hume Center for National Security and Technology, Virginia Polytechnic Institute and State University, Blacksburg, VA, USATed and Karyn Hume Center for National Security and Technology, Virginia Polytechnic Institute and State University, Blacksburg, VA, USAThis article addresses the question of implementing a maximum flow algorithm on directed graphs in a formulation suitable for a quantum annealing computer. Three distinct approaches are presented. In all three cases, the flow problem is formulated as a quadratic unconstrained binary optimization (QUBO) problem amenable to quantum annealing. The first implementation augments a graph with integral edge capacities into a multigraph with unit-capacity edges and encodes the fundamental objective and constraints of the maximum flow problem using a number of qubits equal to the total capacity of the graph $\sum _i{c_i}$. The second implementation, which encodes flows through edges using a binary representation, reduces the required number of qubits to $\mathcal {O}(|E| \log C_{\max })$, where $|E|$ and $C_{\max }$ denote the number of edges and maximum edge capacity of the graph, respectively. The third implementation adapts the dual minimum cut formulation and encodes the problem instance using $|V|$ qubits, where $|V|$ is the number of vertices in the graph. Scaling factors for penalty terms and coupling matrix construction times are made explicit in this article.https://ieeexplore.ieee.org/document/9224181/Maximum flow problemminimum cut problemquantum annealingquantum computingsimulated annealing
spellingShingle Thomas Krauss
Joey McCollum
Chapman Pendery
Sierra Litwin
Alan J. Michaels
Solving the Max-Flow Problem on a Quantum Annealing Computer
IEEE Transactions on Quantum Engineering
Maximum flow problem
minimum cut problem
quantum annealing
quantum computing
simulated annealing
title Solving the Max-Flow Problem on a Quantum Annealing Computer
title_full Solving the Max-Flow Problem on a Quantum Annealing Computer
title_fullStr Solving the Max-Flow Problem on a Quantum Annealing Computer
title_full_unstemmed Solving the Max-Flow Problem on a Quantum Annealing Computer
title_short Solving the Max-Flow Problem on a Quantum Annealing Computer
title_sort solving the max flow problem on a quantum annealing computer
topic Maximum flow problem
minimum cut problem
quantum annealing
quantum computing
simulated annealing
url https://ieeexplore.ieee.org/document/9224181/
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