Postprocessing Variationally Scheduled Quantum Algorithm for Constrained Combinatorial Optimization Problems

In this article, we propose a postprocessing variationally scheduled quantum algorithm (pVSQA) for solving constrained combinatorial optimization problems (COPs). COPs are typically transformed into ground-state search problems of the Ising model on a quantum annealer or gate-based quantum device. V...

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Main Authors: Tatsuhiko Shirai, Nozomu Togawa
Format: Article
Language:English
Published: IEEE 2024-01-01
Series:IEEE Transactions on Quantum Engineering
Subjects:
Online Access:https://ieeexplore.ieee.org/document/10472069/
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author Tatsuhiko Shirai
Nozomu Togawa
author_facet Tatsuhiko Shirai
Nozomu Togawa
author_sort Tatsuhiko Shirai
collection DOAJ
description In this article, we propose a postprocessing variationally scheduled quantum algorithm (pVSQA) for solving constrained combinatorial optimization problems (COPs). COPs are typically transformed into ground-state search problems of the Ising model on a quantum annealer or gate-based quantum device. Variational methods are used to find an optimal schedule function that leads to high-quality solutions in a short amount of time. Postprocessing techniques convert the output solutions of the quantum devices to satisfy the constraints of the COPs. The pVSQA combines the variational methods and the postprocessing technique. We obtain a sufficient condition for constrained COPs to apply the pVSQA based on a greedy postprocessing algorithm. We apply the proposed method to two constrained NP-hard COPs: the graph partitioning problem and the quadratic knapsack problem. The pVSQA on a simulator shows that a small number of variational parameters is sufficient to achieve a (near-) optimal performance within a predetermined operation time. Then, building upon the simulator results, we implement the pVSQA on a quantum annealer and a gate-based quantum device. The experimental results demonstrate the effectiveness of our proposed method.
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spelling doaj.art-53919177b93a49f4ab12835ba7e938dc2024-04-11T23:00:54ZengIEEEIEEE Transactions on Quantum Engineering2689-18082024-01-01511410.1109/TQE.2024.337672110472069Postprocessing Variationally Scheduled Quantum Algorithm for Constrained Combinatorial Optimization ProblemsTatsuhiko Shirai0https://orcid.org/0000-0001-7375-4119Nozomu Togawa1https://orcid.org/0000-0003-3400-3587Department of Computer Science and Communications Engineering, Waseda University, Tokyo, JapanDepartment of Computer Science and Communications Engineering, Waseda University, Tokyo, JapanIn this article, we propose a postprocessing variationally scheduled quantum algorithm (pVSQA) for solving constrained combinatorial optimization problems (COPs). COPs are typically transformed into ground-state search problems of the Ising model on a quantum annealer or gate-based quantum device. Variational methods are used to find an optimal schedule function that leads to high-quality solutions in a short amount of time. Postprocessing techniques convert the output solutions of the quantum devices to satisfy the constraints of the COPs. The pVSQA combines the variational methods and the postprocessing technique. We obtain a sufficient condition for constrained COPs to apply the pVSQA based on a greedy postprocessing algorithm. We apply the proposed method to two constrained NP-hard COPs: the graph partitioning problem and the quadratic knapsack problem. The pVSQA on a simulator shows that a small number of variational parameters is sufficient to achieve a (near-) optimal performance within a predetermined operation time. Then, building upon the simulator results, we implement the pVSQA on a quantum annealer and a gate-based quantum device. The experimental results demonstrate the effectiveness of our proposed method.https://ieeexplore.ieee.org/document/10472069/Combinatorial optimization problem (COP)Ising modelmetaheuristicsquantum devicevariational quantum algorithm
spellingShingle Tatsuhiko Shirai
Nozomu Togawa
Postprocessing Variationally Scheduled Quantum Algorithm for Constrained Combinatorial Optimization Problems
IEEE Transactions on Quantum Engineering
Combinatorial optimization problem (COP)
Ising model
metaheuristics
quantum device
variational quantum algorithm
title Postprocessing Variationally Scheduled Quantum Algorithm for Constrained Combinatorial Optimization Problems
title_full Postprocessing Variationally Scheduled Quantum Algorithm for Constrained Combinatorial Optimization Problems
title_fullStr Postprocessing Variationally Scheduled Quantum Algorithm for Constrained Combinatorial Optimization Problems
title_full_unstemmed Postprocessing Variationally Scheduled Quantum Algorithm for Constrained Combinatorial Optimization Problems
title_short Postprocessing Variationally Scheduled Quantum Algorithm for Constrained Combinatorial Optimization Problems
title_sort postprocessing variationally scheduled quantum algorithm for constrained combinatorial optimization problems
topic Combinatorial optimization problem (COP)
Ising model
metaheuristics
quantum device
variational quantum algorithm
url https://ieeexplore.ieee.org/document/10472069/
work_keys_str_mv AT tatsuhikoshirai postprocessingvariationallyscheduledquantumalgorithmforconstrainedcombinatorialoptimizationproblems
AT nozomutogawa postprocessingvariationallyscheduledquantumalgorithmforconstrainedcombinatorialoptimizationproblems