Energy-dependent barren plateau in bosonic variational quantum circuits

Fuente: arXiv
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Hauptverfasser: Zhang, Bingzhi, Zhuang, Quntao
Format: Preprint
Veröffentlicht: 2023
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author Zhang, Bingzhi
Zhuang, Quntao
author_facet Zhang, Bingzhi
Zhuang, Quntao
contents Bosonic continuous-variable Variational quantum circuits (VQCs) are crucial for information processing in cavity quantum electrodynamics and optical systems, widely applicable in quantum communication, sensing and error correction. The trainability of such VQCs is less understood, hindered by the lack of theoretical tools such as $t$-design due to the infinite dimension of the physical systems involved. We overcome this difficulty to reveal an energy-dependent barren plateau in such VQCs. The variance of the gradient decays as $1/E^{Mν}$, exponential in the number of modes $M$ but polynomial in the (per-mode) circuit energy $E$. The exponent $ν=1$ for shallow circuits and $ν=2$ for deep circuits. We prove these results for state preparation of general Gaussian states and number states. We also provide numerical evidence that the results extend to general state preparation tasks. As circuit energy is a controllable parameter, we provide a strategy to mitigate the barren plateau in continuous-variable VQCs.
format Preprint
id arxiv_https___arxiv_org_abs_2305_01799
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Energy-dependent barren plateau in bosonic variational quantum circuits
Zhang, Bingzhi
Zhuang, Quntao
Quantum Physics
Machine Learning
Bosonic continuous-variable Variational quantum circuits (VQCs) are crucial for information processing in cavity quantum electrodynamics and optical systems, widely applicable in quantum communication, sensing and error correction. The trainability of such VQCs is less understood, hindered by the lack of theoretical tools such as $t$-design due to the infinite dimension of the physical systems involved. We overcome this difficulty to reveal an energy-dependent barren plateau in such VQCs. The variance of the gradient decays as $1/E^{Mν}$, exponential in the number of modes $M$ but polynomial in the (per-mode) circuit energy $E$. The exponent $ν=1$ for shallow circuits and $ν=2$ for deep circuits. We prove these results for state preparation of general Gaussian states and number states. We also provide numerical evidence that the results extend to general state preparation tasks. As circuit energy is a controllable parameter, we provide a strategy to mitigate the barren plateau in continuous-variable VQCs.
title Energy-dependent barren plateau in bosonic variational quantum circuits
topic Quantum Physics
Machine Learning
url https://arxiv.org/abs/2305.01799