Quantum speed-ups for solving semidefinite relaxations of polynomial optimization

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Main Authors: França, Daniel Stilck, Mai, Ngoc Hoang Anh
Format: Preprint
Published: 2025
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author França, Daniel Stilck
Mai, Ngoc Hoang Anh
author_facet França, Daniel Stilck
Mai, Ngoc Hoang Anh
contents We study quantum algorithms for approximating Lasserre's hierarchy values for polynomial optimization. Let $f,g_1,\ldots,g_m$ be real polynomials in $n$ variables and $f^\star$ the infimum of $f$ over the semialgebraic set $S(g)=\{x: g_i(x)\ge 0\}$. Let $λ_k$ be the value of the order-$k$ Lasserre relaxation. Assume either (i) $f^\star=λ_k$ and the optimum is attained in the $\ell_1$-ball of radius $1/2$, or (ii) $S(g)$ lies in the simplex $\{x\ge 0: \sum_j x_j\le 1/2\}$, and the constraints define this simplex. After an appropriate coefficient rescaling, we give a quantum algorithm based on matrix multiplicative weights that approximates $λ_k$ to accuracy $\varepsilon>0$ with runtime, for fixed $k$, \[ O(n^k\varepsilon^{-4}+n^{k/2}\varepsilon^{-5}),\qquad O\!\left(s_g\!\left[n^k\varepsilon^{-4}+\!\left(n^{k}+\!\sum_{i=1}^m n^{k-d_i}\right)^{1/2}\!\varepsilon^{-5}\right]\right), \] where $s_g$ bounds the sparsity of the coefficient-matching matrices associated with the constraints. Classical matrix multiplicative-weights methods scale as $O(n^{3k}\mathrm{poly}(1/\varepsilon))$ even in the unconstrained case. As an example, we obtain an $O(n\varepsilon^{-4}+\sqrt{n}\varepsilon^{-5})$ quantum algorithm for portfolio optimization, improving over the classical $O(n^{ω+1}\log(1/\varepsilon))$ bound with $ω\approx2.373$. Our approach builds on and sharpens the analysis of Apeldoorn and Gilyén for the SDPs arising in polynomial optimization. We also show how to implement the required block encodings without QRAM. Under the stated assumptions, our method achieves a super-quadratic speedup in the problem dimension for computing Lasserre relaxations.
format Preprint
id arxiv_https___arxiv_org_abs_2511_14389
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum speed-ups for solving semidefinite relaxations of polynomial optimization
França, Daniel Stilck
Mai, Ngoc Hoang Anh
Quantum Physics
Optimization and Control
We study quantum algorithms for approximating Lasserre's hierarchy values for polynomial optimization. Let $f,g_1,\ldots,g_m$ be real polynomials in $n$ variables and $f^\star$ the infimum of $f$ over the semialgebraic set $S(g)=\{x: g_i(x)\ge 0\}$. Let $λ_k$ be the value of the order-$k$ Lasserre relaxation. Assume either (i) $f^\star=λ_k$ and the optimum is attained in the $\ell_1$-ball of radius $1/2$, or (ii) $S(g)$ lies in the simplex $\{x\ge 0: \sum_j x_j\le 1/2\}$, and the constraints define this simplex. After an appropriate coefficient rescaling, we give a quantum algorithm based on matrix multiplicative weights that approximates $λ_k$ to accuracy $\varepsilon>0$ with runtime, for fixed $k$, \[ O(n^k\varepsilon^{-4}+n^{k/2}\varepsilon^{-5}),\qquad O\!\left(s_g\!\left[n^k\varepsilon^{-4}+\!\left(n^{k}+\!\sum_{i=1}^m n^{k-d_i}\right)^{1/2}\!\varepsilon^{-5}\right]\right), \] where $s_g$ bounds the sparsity of the coefficient-matching matrices associated with the constraints. Classical matrix multiplicative-weights methods scale as $O(n^{3k}\mathrm{poly}(1/\varepsilon))$ even in the unconstrained case. As an example, we obtain an $O(n\varepsilon^{-4}+\sqrt{n}\varepsilon^{-5})$ quantum algorithm for portfolio optimization, improving over the classical $O(n^{ω+1}\log(1/\varepsilon))$ bound with $ω\approx2.373$. Our approach builds on and sharpens the analysis of Apeldoorn and Gilyén for the SDPs arising in polynomial optimization. We also show how to implement the required block encodings without QRAM. Under the stated assumptions, our method achieves a super-quadratic speedup in the problem dimension for computing Lasserre relaxations.
title Quantum speed-ups for solving semidefinite relaxations of polynomial optimization
topic Quantum Physics
Optimization and Control
url https://arxiv.org/abs/2511.14389