Quantum Solution Framework for Finite-Horizon LQG Control via Block Encodings and QSVT

Fuente: arXiv
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Autori principali: Dehaghani, Nahid Binandeh, Wisniewski, Rafal, Aguiar, A. Pedro
Natura: Preprint
Pubblicazione: 2025
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author Dehaghani, Nahid Binandeh
Wisniewski, Rafal
Aguiar, A. Pedro
author_facet Dehaghani, Nahid Binandeh
Wisniewski, Rafal
Aguiar, A. Pedro
contents We present a quantum algorithm for solving the finite-horizon discrete-time Linear Quadratic Gaussian (LQG) control problem, which integrates optimal control and state estimation in the presence of stochastic disturbances and noise. Classical approaches to LQG require solving a backward Riccati recursion and a forward Kalman filter, both requiring computationally expensive matrix operations with overall time complexity $\mathcal{O}(T n^3)$, where $n$ is the system dimension and $T$ is the time horizon. While efficient classical solvers exist, especially for small to medium-sized systems, their computational complexity grows rapidly with system dimension. To address this, we reformulate the full LQG pipeline using quantum linear algebra primitives, including block-encoded matrix representations and quantum singular value transformation (QSVT) techniques for matrix inversion and multiplication. We formally analyze the time complexity of each algorithmic component. Under standard assumptions on matrix condition numbers and encoding precision, the total runtime of the quantum LQG algorithm scales polylogarithmically with the system dimension $n$ and linearly with the time horizon $T$, offering an asymptotic quantum speedup over classical methods.
format Preprint
id arxiv_https___arxiv_org_abs_2507_09841
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum Solution Framework for Finite-Horizon LQG Control via Block Encodings and QSVT
Dehaghani, Nahid Binandeh
Wisniewski, Rafal
Aguiar, A. Pedro
Quantum Physics
We present a quantum algorithm for solving the finite-horizon discrete-time Linear Quadratic Gaussian (LQG) control problem, which integrates optimal control and state estimation in the presence of stochastic disturbances and noise. Classical approaches to LQG require solving a backward Riccati recursion and a forward Kalman filter, both requiring computationally expensive matrix operations with overall time complexity $\mathcal{O}(T n^3)$, where $n$ is the system dimension and $T$ is the time horizon. While efficient classical solvers exist, especially for small to medium-sized systems, their computational complexity grows rapidly with system dimension. To address this, we reformulate the full LQG pipeline using quantum linear algebra primitives, including block-encoded matrix representations and quantum singular value transformation (QSVT) techniques for matrix inversion and multiplication. We formally analyze the time complexity of each algorithmic component. Under standard assumptions on matrix condition numbers and encoding precision, the total runtime of the quantum LQG algorithm scales polylogarithmically with the system dimension $n$ and linearly with the time horizon $T$, offering an asymptotic quantum speedup over classical methods.
title Quantum Solution Framework for Finite-Horizon LQG Control via Block Encodings and QSVT
topic Quantum Physics
url https://arxiv.org/abs/2507.09841