Gradients of unitary optical neural networks using parameter-shift rule

Fuente: arXiv
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Main Authors: Jiang, Jinzhe, Zhao, Yaqian, Zhang, Xin, Li, Chen, Yu, Yunlong, Liu, Hailing
Format: Preprint
Published: 2025
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_version_ 1866918057779134464
author Jiang, Jinzhe
Zhao, Yaqian
Zhang, Xin
Li, Chen
Yu, Yunlong
Liu, Hailing
author_facet Jiang, Jinzhe
Zhao, Yaqian
Zhang, Xin
Li, Chen
Yu, Yunlong
Liu, Hailing
contents This paper explores the application of the parameter-shift rule (PSR) for computing gradients in unitary optical neural networks (UONNs). While backpropagation has been fundamental to training conventional neural networks, its implementation in optical neural networks faces significant challenges due to the physical constraints of optical systems. We demonstrate how PSR, which calculates gradients by evaluating functions at shifted parameter values, can be effectively adapted for training UONNs constructed from Mach-Zehnder interferometer meshes. The method leverages the inherent Fourier series nature of optical interference in these systems to compute exact analytical gradients directly from hardware measurements. This approach offers a promising alternative to traditional in silico training methods and circumvents the limitations of both finite difference approximations and all-optical backpropagation implementations. We present the theoretical framework and practical methodology for applying PSR to optimize phase parameters in optical neural networks, potentially advancing the development of efficient hardware-based training strategies for optical computing systems.
format Preprint
id arxiv_https___arxiv_org_abs_2506_11565
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Gradients of unitary optical neural networks using parameter-shift rule
Jiang, Jinzhe
Zhao, Yaqian
Zhang, Xin
Li, Chen
Yu, Yunlong
Liu, Hailing
Emerging Technologies
Machine Learning
Optics
This paper explores the application of the parameter-shift rule (PSR) for computing gradients in unitary optical neural networks (UONNs). While backpropagation has been fundamental to training conventional neural networks, its implementation in optical neural networks faces significant challenges due to the physical constraints of optical systems. We demonstrate how PSR, which calculates gradients by evaluating functions at shifted parameter values, can be effectively adapted for training UONNs constructed from Mach-Zehnder interferometer meshes. The method leverages the inherent Fourier series nature of optical interference in these systems to compute exact analytical gradients directly from hardware measurements. This approach offers a promising alternative to traditional in silico training methods and circumvents the limitations of both finite difference approximations and all-optical backpropagation implementations. We present the theoretical framework and practical methodology for applying PSR to optimize phase parameters in optical neural networks, potentially advancing the development of efficient hardware-based training strategies for optical computing systems.
title Gradients of unitary optical neural networks using parameter-shift rule
topic Emerging Technologies
Machine Learning
Optics
url https://arxiv.org/abs/2506.11565