Towards Optimal Convergence Rates for the Quantum Central Limit Theorem

Fuente: arXiv
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Autores principales: Beigi, Salman, Mehrabi, Hami
Formato: Preprint
Publicado: 2023
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author Beigi, Salman
Mehrabi, Hami
author_facet Beigi, Salman
Mehrabi, Hami
contents The quantum central limit theorem for bosonic quantum systems states that the sequence of states $ρ^{\boxplus n}$ obtained from the $n$-fold convolution of a centered quantum state $ρ$ converges to a quantum Gaussian state $ρ_G$ that has the same first and second moments as $ρ$. In this paper, we contribute to the problem of finding the optimal rate of convergence for this quantum central limit theorem. We first show that if an $m$-mode quantum state has a finite moment of order $\max\{3, 2m\}$, then we have $\|ρ^{\boxplus n} - ρ_G\|_1=\mathcal O(n^{-1/2})$. We also introduce a notion of Poincaré inequality for quantum states and show that if $ρ$ satisfies this Poincaré inequality, then $D(ρ^{\boxplus n}\| ρ_G)= \mathcal O(n^{-1})$. By giving an explicit example, we verify that both these convergence rates are optimal.
format Preprint
id arxiv_https___arxiv_org_abs_2310_09812
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Towards Optimal Convergence Rates for the Quantum Central Limit Theorem
Beigi, Salman
Mehrabi, Hami
Quantum Physics
The quantum central limit theorem for bosonic quantum systems states that the sequence of states $ρ^{\boxplus n}$ obtained from the $n$-fold convolution of a centered quantum state $ρ$ converges to a quantum Gaussian state $ρ_G$ that has the same first and second moments as $ρ$. In this paper, we contribute to the problem of finding the optimal rate of convergence for this quantum central limit theorem. We first show that if an $m$-mode quantum state has a finite moment of order $\max\{3, 2m\}$, then we have $\|ρ^{\boxplus n} - ρ_G\|_1=\mathcal O(n^{-1/2})$. We also introduce a notion of Poincaré inequality for quantum states and show that if $ρ$ satisfies this Poincaré inequality, then $D(ρ^{\boxplus n}\| ρ_G)= \mathcal O(n^{-1})$. By giving an explicit example, we verify that both these convergence rates are optimal.
title Towards Optimal Convergence Rates for the Quantum Central Limit Theorem
topic Quantum Physics
url https://arxiv.org/abs/2310.09812