Efficient learning of bosonic Gaussian unitaries

Fuente: arXiv
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Main Authors: Fanizza, Marco, Iyer, Vishnu, Lee, Junseo, Mele, Antonio A., Mele, Francesco A.
Format: Preprint
Published: 2025
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author Fanizza, Marco
Iyer, Vishnu
Lee, Junseo
Mele, Antonio A.
Mele, Francesco A.
author_facet Fanizza, Marco
Iyer, Vishnu
Lee, Junseo
Mele, Antonio A.
Mele, Francesco A.
contents Bosonic Gaussian unitaries are fundamental building blocks of central continuous-variable quantum technologies such as quantum-optic interferometry and bosonic error-correction schemes. In this work, we present the first time-efficient algorithm for learning bosonic Gaussian unitaries with a rigorous analysis. Our algorithm produces an estimate of the unknown unitary that is accurate to small worst-case error, measured by the physically motivated energy-constrained diamond distance. Its runtime and query complexity scale polynomially with the number of modes, the inverse target accuracy, and natural energy parameters quantifying the allowed input energy and the unitary's output-energy growth. The protocol uses only experimentally friendly photonic resources: coherent and squeezed probes, passive linear optics, and heterodyne/homodyne detection. We then employ an efficient classical post-processing routine that leverages a symplectic regularization step to project matrix estimates onto the symplectic group. In the limit of unbounded input energy, our procedure attains arbitrarily high precision using only $2m+2$ queries, where $m$ is the number of modes. To our knowledge, this is the first provably efficient learning algorithm for a multiparameter family of continuous-variable unitaries.
format Preprint
id arxiv_https___arxiv_org_abs_2510_05531
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Efficient learning of bosonic Gaussian unitaries
Fanizza, Marco
Iyer, Vishnu
Lee, Junseo
Mele, Antonio A.
Mele, Francesco A.
Quantum Physics
Data Structures and Algorithms
Machine Learning
Bosonic Gaussian unitaries are fundamental building blocks of central continuous-variable quantum technologies such as quantum-optic interferometry and bosonic error-correction schemes. In this work, we present the first time-efficient algorithm for learning bosonic Gaussian unitaries with a rigorous analysis. Our algorithm produces an estimate of the unknown unitary that is accurate to small worst-case error, measured by the physically motivated energy-constrained diamond distance. Its runtime and query complexity scale polynomially with the number of modes, the inverse target accuracy, and natural energy parameters quantifying the allowed input energy and the unitary's output-energy growth. The protocol uses only experimentally friendly photonic resources: coherent and squeezed probes, passive linear optics, and heterodyne/homodyne detection. We then employ an efficient classical post-processing routine that leverages a symplectic regularization step to project matrix estimates onto the symplectic group. In the limit of unbounded input energy, our procedure attains arbitrarily high precision using only $2m+2$ queries, where $m$ is the number of modes. To our knowledge, this is the first provably efficient learning algorithm for a multiparameter family of continuous-variable unitaries.
title Efficient learning of bosonic Gaussian unitaries
topic Quantum Physics
Data Structures and Algorithms
Machine Learning
url https://arxiv.org/abs/2510.05531