The Second Moment of Hafnians in Gaussian Boson Sampling

Fuente: arXiv
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Autores principales: Ehrenberg, Adam, Iosue, Joseph T., Deshpande, Abhinav, Hangleiter, Dominik, Gorshkov, Alexey V.
Formato: Preprint
Publicado: 2024
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author Ehrenberg, Adam
Iosue, Joseph T.
Deshpande, Abhinav
Hangleiter, Dominik
Gorshkov, Alexey V.
author_facet Ehrenberg, Adam
Iosue, Joseph T.
Deshpande, Abhinav
Hangleiter, Dominik
Gorshkov, Alexey V.
contents Gaussian Boson Sampling is a popular method for experimental demonstrations of quantum advantage, but many subtleties remain in fully understanding its theoretical underpinnings. An important component in the theoretical arguments for approximate average-case hardness of sampling is anticoncentration, which is a second-moment property of the output probabilities. In Gaussian Boson Sampling these are given by hafnians of generalized circular orthogonal ensemble matrices. In a companion work [arXiv:2312.08433], we develop a graph-theoretic method to study these moments and use it to identify a transition in anticoncentration. In this work, we find a recursive expression for the second moment using these graph-theoretic techniques. While we have not been able to solve this recursion by hand, we are able to solve it numerically exactly, which we do up to Fock sector $2n = 80$. We further derive new analytical results about the second moment. These results allow us to pinpoint the transition in anticoncentration and furthermore yield the expected linear cross-entropy benchmarking score for an ideal (error-free) device.
format Preprint
id arxiv_https___arxiv_org_abs_2403_13878
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Second Moment of Hafnians in Gaussian Boson Sampling
Ehrenberg, Adam
Iosue, Joseph T.
Deshpande, Abhinav
Hangleiter, Dominik
Gorshkov, Alexey V.
Quantum Physics
Gaussian Boson Sampling is a popular method for experimental demonstrations of quantum advantage, but many subtleties remain in fully understanding its theoretical underpinnings. An important component in the theoretical arguments for approximate average-case hardness of sampling is anticoncentration, which is a second-moment property of the output probabilities. In Gaussian Boson Sampling these are given by hafnians of generalized circular orthogonal ensemble matrices. In a companion work [arXiv:2312.08433], we develop a graph-theoretic method to study these moments and use it to identify a transition in anticoncentration. In this work, we find a recursive expression for the second moment using these graph-theoretic techniques. While we have not been able to solve this recursion by hand, we are able to solve it numerically exactly, which we do up to Fock sector $2n = 80$. We further derive new analytical results about the second moment. These results allow us to pinpoint the transition in anticoncentration and furthermore yield the expected linear cross-entropy benchmarking score for an ideal (error-free) device.
title The Second Moment of Hafnians in Gaussian Boson Sampling
topic Quantum Physics
url https://arxiv.org/abs/2403.13878