Variational quantum multiobjective optimization

Solving combinatorial optimization problems on near-term quantum devices has gained a lot of attention in recent years. Currently, most studies have focused on single-objective problems, whereas many real-world applications need to consider multiple, mostly conflicting objectives, such as cost and q...

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Bibliographic Details
Main Authors: Linus Ekstrom, Hao Wang, Sebastian Schmitt
Format: Article
Language:English
Published: American Physical Society 2025-05-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.7.023141
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Summary:Solving combinatorial optimization problems on near-term quantum devices has gained a lot of attention in recent years. Currently, most studies have focused on single-objective problems, whereas many real-world applications need to consider multiple, mostly conflicting objectives, such as cost and quality. We present a variational quantum optimization algorithm to solve discrete multiobjective optimization problems on quantum computers. The proposed quantum multiobjective optimization (QMOO) algorithm incorporates all cost Hamiltonians representing the classical objective functions in the quantum circuit and produces a quantum state consisting of Pareto-optimal solutions in superposition. From this state, we retrieve a set of solutions and utilize the widely applied hypervolume indicator to determine its quality as an approximation to the Pareto front. The variational parameters of the QMOO circuit are tuned by maximizing the hypervolume indicator in a quantum-classical hybrid fashion. We show the effectiveness of the proposed algorithm on several benchmark problems with up to five objectives. We investigate the influence of the classical optimizer and the circuit depth, and compare them to results from classical optimization algorithms. We find that the algorithm is robust to shot noise and produces good results with as few as 128 measurement shots in each iteration. These promising results open the possibility to run the algorithm on near-term quantum hardware.
ISSN:2643-1564