QSlack: A slack-variable approach for variational quantum semi-definite programming

Fuente: arXiv
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Main Authors: Chen, Jingxuan, Westerheim, Hanna, Holmes, Zoë, Luo, Ivy, Nuradha, Theshani, Patel, Dhrumil, Rethinasamy, Soorya, Wang, Kathie, Wilde, Mark M.
Format: Preprint
Published: 2023
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author Chen, Jingxuan
Westerheim, Hanna
Holmes, Zoë
Luo, Ivy
Nuradha, Theshani
Patel, Dhrumil
Rethinasamy, Soorya
Wang, Kathie
Wilde, Mark M.
author_facet Chen, Jingxuan
Westerheim, Hanna
Holmes, Zoë
Luo, Ivy
Nuradha, Theshani
Patel, Dhrumil
Rethinasamy, Soorya
Wang, Kathie
Wilde, Mark M.
contents Solving optimization problems is a key task for which quantum computers could possibly provide a speedup over the best known classical algorithms. Particular classes of optimization problems including semi-definite programming (SDP) and linear programming (LP) have wide applicability in many domains of computer science, engineering, mathematics, and physics. Here we focus on semi-definite and linear programs for which the dimensions of the variables involved are exponentially large, so that standard classical SDP and LP solvers are not helpful for such large-scale problems. We propose the QSlack and CSlack methods for estimating their optimal values, respectively, which work by 1) introducing slack variables to transform inequality constraints to equality constraints, 2) transforming a constrained optimization to an unconstrained one via the penalty method, and 3) replacing the optimizations over all possible non-negative variables by optimizations over parameterized quantum states and parameterized probability distributions. Under the assumption that the SDP and LP inputs are efficiently measurable observables, it follows that all terms in the resulting objective functions are efficiently estimable by either a quantum computer in the SDP case or a quantum or probabilistic computer in the LP case. Furthermore, by making use of SDP and LP duality theory, we prove that these methods provide a theoretical guarantee that, if one could find global optima of the objective functions, then the resulting values sandwich the true optimal values from both above and below. Finally, we showcase the QSlack and CSlack methods on a variety of example optimization problems and discuss details of our implementation, as well as the resulting performance. We find that our implementations of both the primal and dual for these problems approach the ground truth, typically achieving errors of order $10^{-2}$.
format Preprint
id arxiv_https___arxiv_org_abs_2312_03830
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle QSlack: A slack-variable approach for variational quantum semi-definite programming
Chen, Jingxuan
Westerheim, Hanna
Holmes, Zoë
Luo, Ivy
Nuradha, Theshani
Patel, Dhrumil
Rethinasamy, Soorya
Wang, Kathie
Wilde, Mark M.
Quantum Physics
Solving optimization problems is a key task for which quantum computers could possibly provide a speedup over the best known classical algorithms. Particular classes of optimization problems including semi-definite programming (SDP) and linear programming (LP) have wide applicability in many domains of computer science, engineering, mathematics, and physics. Here we focus on semi-definite and linear programs for which the dimensions of the variables involved are exponentially large, so that standard classical SDP and LP solvers are not helpful for such large-scale problems. We propose the QSlack and CSlack methods for estimating their optimal values, respectively, which work by 1) introducing slack variables to transform inequality constraints to equality constraints, 2) transforming a constrained optimization to an unconstrained one via the penalty method, and 3) replacing the optimizations over all possible non-negative variables by optimizations over parameterized quantum states and parameterized probability distributions. Under the assumption that the SDP and LP inputs are efficiently measurable observables, it follows that all terms in the resulting objective functions are efficiently estimable by either a quantum computer in the SDP case or a quantum or probabilistic computer in the LP case. Furthermore, by making use of SDP and LP duality theory, we prove that these methods provide a theoretical guarantee that, if one could find global optima of the objective functions, then the resulting values sandwich the true optimal values from both above and below. Finally, we showcase the QSlack and CSlack methods on a variety of example optimization problems and discuss details of our implementation, as well as the resulting performance. We find that our implementations of both the primal and dual for these problems approach the ground truth, typically achieving errors of order $10^{-2}$.
title QSlack: A slack-variable approach for variational quantum semi-definite programming
topic Quantum Physics
url https://arxiv.org/abs/2312.03830