Nonlinear transformation of complex amplitudes via quantum singular value transformation

Due to the linearity of quantum operations, it is not straightforward to implement nonlinear transformations on a quantum computer, making some practical tasks like a neural network hard to achieve. In this paper, we define a task called nonlinear transformation of complex amplitudes and provide an...

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Main Authors: Naixu Guo, Kosuke Mitarai, Keisuke Fujii
Format: Article
Language:English
Published: American Physical Society 2024-12-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.6.043227
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author Naixu Guo
Kosuke Mitarai
Keisuke Fujii
author_facet Naixu Guo
Kosuke Mitarai
Keisuke Fujii
author_sort Naixu Guo
collection DOAJ
description Due to the linearity of quantum operations, it is not straightforward to implement nonlinear transformations on a quantum computer, making some practical tasks like a neural network hard to achieve. In this paper, we define a task called nonlinear transformation of complex amplitudes and provide an algorithm to achieve this task. Specifically, we construct a block encoding of complex amplitudes from a state preparation unitary. This allows us to transform the complex amplitudes by using quantum singular value transformation. We evaluate the required overhead in terms of input dimension and precision, which reveals that the algorithm depends on the roughly square root of input dimension and achieves an exponential speedup on precision compared with previous work. We also discuss its possible applications to quantum machine learning, where complex amplitudes encoding classical or quantum data are processed by the proposed method. In this paper, we provide a promising way to introduce the highly complex nonlinearity of the quantum states, which is essentially missing in quantum mechanics.
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publishDate 2024-12-01
publisher American Physical Society
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spelling doaj-art-9f12b6e961f8492898e1b4dc8c65b06a2024-12-02T16:13:51ZengAmerican Physical SocietyPhysical Review Research2643-15642024-12-016404322710.1103/PhysRevResearch.6.043227Nonlinear transformation of complex amplitudes via quantum singular value transformationNaixu GuoKosuke MitaraiKeisuke FujiiDue to the linearity of quantum operations, it is not straightforward to implement nonlinear transformations on a quantum computer, making some practical tasks like a neural network hard to achieve. In this paper, we define a task called nonlinear transformation of complex amplitudes and provide an algorithm to achieve this task. Specifically, we construct a block encoding of complex amplitudes from a state preparation unitary. This allows us to transform the complex amplitudes by using quantum singular value transformation. We evaluate the required overhead in terms of input dimension and precision, which reveals that the algorithm depends on the roughly square root of input dimension and achieves an exponential speedup on precision compared with previous work. We also discuss its possible applications to quantum machine learning, where complex amplitudes encoding classical or quantum data are processed by the proposed method. In this paper, we provide a promising way to introduce the highly complex nonlinearity of the quantum states, which is essentially missing in quantum mechanics.http://doi.org/10.1103/PhysRevResearch.6.043227
spellingShingle Naixu Guo
Kosuke Mitarai
Keisuke Fujii
Nonlinear transformation of complex amplitudes via quantum singular value transformation
Physical Review Research
title Nonlinear transformation of complex amplitudes via quantum singular value transformation
title_full Nonlinear transformation of complex amplitudes via quantum singular value transformation
title_fullStr Nonlinear transformation of complex amplitudes via quantum singular value transformation
title_full_unstemmed Nonlinear transformation of complex amplitudes via quantum singular value transformation
title_short Nonlinear transformation of complex amplitudes via quantum singular value transformation
title_sort nonlinear transformation of complex amplitudes via quantum singular value transformation
url http://doi.org/10.1103/PhysRevResearch.6.043227
work_keys_str_mv AT naixuguo nonlineartransformationofcomplexamplitudesviaquantumsingularvaluetransformation
AT kosukemitarai nonlineartransformationofcomplexamplitudesviaquantumsingularvaluetransformation
AT keisukefujii nonlineartransformationofcomplexamplitudesviaquantumsingularvaluetransformation