arXiv:2610.41788
Query-Efficient Quantum Multi-Objective Optimization for Materials Configuration Search via Bayesian Weight Selection
Onur Boyar, Seiji Takeda, Akihiro Kosugi, Indra Priyadarsini S, Lisa Hamada, Sina Klampt
Abstract
Materials design is a multi-objective problem, and recent advances in quantum optimization make it possible to bring quantum solvers to bear on such problems. The realistic near-term win, though, is not raw quantum advantage but making an expensive, noisy quantum solver usable by spending its calls wisely. Quantum Approximate Multi-Objective Optimization (QAMOO) traces a Pareto front by solving a family of scalarized Ising problems, one per objective-weight vector, with QAOA --- but chooses those weights \emph{non-adaptively}, sampling them at random, blind to what it has already found. We recast weight selection as \emph{multi-objective Bayesian optimization}: our method, BW-QAMOO (Bayes-Weighted QAMOO), picks each next weight by expected hypervolume improvement (EHVI) under a Gaussian-process (GP) surrogate over the weight-to-objective map. On a frustrated alloy-configuration benchmark across $m\in\{3,4\}$ objectives and $n\in\{10,11,12\}$ sites, BW-QAMOO reaches the same Pareto hypervolume as QAMOO's random sampling with a median 33% fewer scalarized solves across the 90/95\% targets and 60--74\% fewer than a uniform-grid baseline), on a genuine (simulated) QAOA solver; a paired Wilcoxon test confirms the saving is significant, and the advantage grows with the objective count m as the weight simplex expands and blind sampling wastes more of the budget. This is a \emph{query-efficiency} result, and we close with the open challenges on the path to real alloy data and hardware.
AI Summary
The paper asks whether adaptive selection of scalarization weights can reduce the number of QAOA solves needed to approximate a multi-objective Pareto front. QAMOO solves weighted sums of Ising objectives using randomly sampled weights; BW-QAMOO replaces this sampling with Bayesian optimization over the weight simplex, leaving the quantum solver unchanged. The method fits an independent Matérn-$5/2$ Gaussian process for each objective, initialized with solves at the simplex corners. It selects subsequent weights from fresh Dirichlet candidate pools by maximizing predicted hypervolume improvement. Although framed in terms of expected hypervolume improvement, the implemented acquisition evaluates a single optimistic objective vector, $\boldsymbol{\mu}-1.5\boldsymbol{\sigma}$, rather than integrating over the posterior. Experiments use synthetic frustrated Ising instances with $n\in\{10,11,12\}$ sites and $m\in\{3,4\}$ objectives, with ten instances per setting. Each solve uses simulated depth-$2$ QAOA, COBYLA angle optimization, and 4,096 final measurement shots. Performance is measured by solves required to reach 90% or 95% of the exactly enumerated Pareto hypervolume. BW-QAMOO reduces this count by a median 33% relative to random weights, with lower means in all 12 settings. Paired Wilcoxon tests pooled across sizes report significance. Savings against an ordered uniform-grid baseline are 61–74% for four objectives. The stated limitations are small synthetic instances, no hardware execution or device-noise model, and no fitted materials interactions. Weighted-sum scalarization cannot recover unsupported non-convex front regions. Larger instances, real materials data, nonlinear scalarizations, and multicomponent-alloy encodings remain future directions.
Error found: The implemented acquisition uses hypervolume improvement at μ−1.5σ rather than the posterior expected hypervolume improvement claimed in the abstract and Eq. (2). The abstract's 60–74% saving against the grid applies only to the four-objective benchmarks; the three-objective savings in Table 1 are approximately 32–60%. Table 1 reports a mean of 32.3 solves for a baseline described as traversing a 28-weight grid, without explaining repetitions or how unreached targets are scored. Because only BW-QAMOO receives simplex-corner initialization, the reported comparison does not isolate the benefit of adaptation from the benefit of initialization.
Written by gpt-6.1-sol from the paper's full text. Automated: it can be wrong.
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- 11 pages, 2 figures