Improving Quantum Recurrent Neural Networks with Amplitude Encoding

Fuente: arXiv
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Main Authors: Morgan, Jack, Mohammadbagherpoor, Hamed, Ghysels, Eric
Format: Preprint
Published: 2025
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author Morgan, Jack
Mohammadbagherpoor, Hamed
Ghysels, Eric
author_facet Morgan, Jack
Mohammadbagherpoor, Hamed
Ghysels, Eric
contents Quantum machine learning holds promise for advancing time series forecasting. The Quantum Recurrent Neural Network (QRNN), inspired by classical RNNs, encodes temporal data into quantum states that are periodically input into a quantum circuit. While prior QRNN work has predominantly used angle encoding, alternative encoding strategies like amplitude encoding remain underexplored due to their high computational complexity. In this paper, we evaluate and improve amplitude-based QRNNs using EnQode, a recently introduced method for approximate amplitude encoding. We propose a simple pre-processing technique that augments amplitude encoded inputs with their pre-normalized magnitudes, leading to improved generalization on two real world data sets. Additionally, we introduce a novel circuit architecture for the QRNN that is mathematically equivalent to the original model but achieves a substantial reduction in circuit depth. Together, these contributions demonstrate practical improvements to QRNN design in both model performance and quantum resource efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2508_16784
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Improving Quantum Recurrent Neural Networks with Amplitude Encoding
Morgan, Jack
Mohammadbagherpoor, Hamed
Ghysels, Eric
Quantum Physics
Quantum machine learning holds promise for advancing time series forecasting. The Quantum Recurrent Neural Network (QRNN), inspired by classical RNNs, encodes temporal data into quantum states that are periodically input into a quantum circuit. While prior QRNN work has predominantly used angle encoding, alternative encoding strategies like amplitude encoding remain underexplored due to their high computational complexity. In this paper, we evaluate and improve amplitude-based QRNNs using EnQode, a recently introduced method for approximate amplitude encoding. We propose a simple pre-processing technique that augments amplitude encoded inputs with their pre-normalized magnitudes, leading to improved generalization on two real world data sets. Additionally, we introduce a novel circuit architecture for the QRNN that is mathematically equivalent to the original model but achieves a substantial reduction in circuit depth. Together, these contributions demonstrate practical improvements to QRNN design in both model performance and quantum resource efficiency.
title Improving Quantum Recurrent Neural Networks with Amplitude Encoding
topic Quantum Physics
url https://arxiv.org/abs/2508.16784