Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1911.10781

Limitations of Clustering Using Quantum Persistent Homology

Niels M. P. Neumann, Sterre den Breeijen

Published Nov 25, 2019• 3 citations
arXivHTMLPDF

Abstract

Different algorithms can be used for clustering purposes with data sets. On of these algorithms, uses topological features extracted from the data set to base the clusters on. The complexity of this algorithm is however exponential in the number of data points. Recently a quantum algorithm was proposed by Lloyd Garnerone and Zanardi with claimed polynomial complexity, hence an exponential improved over classical algorithms. However, we show that this algorithm in general cannot be used to compute these topological features in any dimension but the zeroth. We also give pointers on how to still use the algorithm for clustering purposes.

DOI
10.48550/arxiv.1911.10781

Related papers

Clustering using Quantum Persistent Homology

R.H.A.J. Meijer

Persistent homology is a way to analyse the shape of a dataset rather than its semantics. This is done by assigning the dataset holes in different dimensions, borrowing this theory from the mathematical area of topology. The dataset is treated as being sampled from a topological space, which is in turn approximated at different resolutions. The persistent Betti numbers then count the number of holes in these spaces, registering for how long the holes persist as the resolution increases. Computing such features classically may prove costly, with some steps possibly requiring exponential time. In a 2016 paper, a polynomial time quantum algorithm for the approximation of persistent homology is promised. In this thesis it is shown these methods are generally incapable of uniquely determining the persistent Betti numbers in arbitrary dimensions. The algorithm does succeed in the zeroth dimension. After treating the prerequisites, the methods from this paper are explained, the above statements are proven, and finally the quantum algorithm is related to agglomerative hierarchical clustering and spectral clustering.

•Jan 1, 2019•2 citations

Quantum algorithms for topological and geometric analysis of big data

Seth Lloyd, Silvano Garnerone, Paolo Zanardi A

Extracting useful information from large data sets can be a daunting task. Topological methods for analyzing data sets provide a powerful technique for extracting such information. Persistent homology is a sophisticated tool for identifying such topological features -- connected components, holes, or voids -- and for determining how such features persist as the data is viewed at different scales. This paper provides quantum algorithms for calculating Betti numbers in persistent homology, and for finding eigenvectors and eigenvalues of the combinatorial Laplacian. The algorithms provide an exponential speedup over classical algorithms for topological data analysis.

arXiv:1408.3106•Aug 13, 2014•11 citations

Quantum Persistent Homology for Time Series

Bernardo Ameneyro, George Siopsis, Vasileios Maroulas

Persistent homology, a powerful mathematical tool for data analysis, summarizes the shape of data through tracking topological features across changes in different scales. Classical algorithms for persistent homol-ogy are often constrained by running times and mem-ory requirements that grow exponentially on the number of data points. To surpass this problem, two quantum algorithms of persistent homology have been developed based on two different approaches. However, both of these quantum algorithms consider a data set in the form of a point cloud, which can be restrictive considering that many data sets come in the form of time series. In this paper, we alleviate this issue by establishing a quantum Takens's delay embedding algorithm, which turns a time series into a point cloud by considering a pertinent embedding into a higher dimensional space. Having this quantum transformation of time series to point clouds, then one may use a quantum persistent homology algorithm to extract the topological features from the point cloud associated with the original times series.

arXiv:2211.04465•IEEE/ACM Symposium on Edge Computing (SEC)•Dec 1, 2022•11 citations

Quantum algorithms for topological and geometric analysis of data

Seth Lloyd, Silvano Garnerone, Paolo Zanardi A

Extracting useful information from large data sets can be a daunting task. Topological methods for analysing data sets provide a powerful technique for extracting such information. Persistent homology is a sophisticated tool for identifying topological features and for determining how such features persist as the data is viewed at different scales. Here we present quantum machine learning algorithms for calculating Betti numbers--the numbers of connected components, holes and voids--in persistent homology, and for finding eigenvectors and eigenvalues of the combinatorial Laplacian. The algorithms provide an exponential speed-up over the best currently known classical algorithms for topological data analysis.

Nature Communications•Jan 25, 2016•241 citations

Quantum encodings that preserve persistent homology

Arthur J. Parzygnat, Andrew Vlasic

Given a data set with a notion of distance, such as a point cloud in Euclidean space, topological data analysis (TDA) uses techniques from algebraic topology and metric geometry to infer the topology of a hypothetical manifold from which the data are sampled. This inference is achieved by calculating topological invariants, some of which are difficult to compute classically. Meanwhile, quantum TDA utilizes quantum processes to extract the invariants used in making such inferences in an attempt to speed up the computations. Because applying transformations to the original classical dataset could alter the associated topological invariants, we investigate which quantum encodings would best preserve the invariants of the original dataset. This line of inquiry is distinct from standard approaches in quantum TDA, whose typical starting point is not from the classical dataset directly, but rather from the associated combinatorial objects, such as simplicial complexes, which typically demand a lot of resources to construct. We take the first step at a more direct approach by focusing on which quantum encodings acting directly on the data are admissible for applying quantum algorithms to extract topological features from classical datasets.

quant-pharXiv:2605.28927•May 29, 2026•0 citations

Complexity-Theoretic Limitations on Quantum Algorithms for Topological Data Analysis

Alexander Schmidhuber, Seth Lloyd

Quantum algorithms for topological data analysis (TDA) seem to provide an exponential advantage over the best classical approach while remaining immune to dequantization procedures and the data-loading problem.In this paper, we give complexity-theoretic evidence that the central task of TDA-estimating Betti numbers-is intractable even for quantum computers.Specifically, we prove that the problem of computing Betti numbers exactly is #P-hard, while the problem of approximating Betti numbers up to multiplicative error is NP-hard.Moreover, both problems retain their hardness if restricted to the regime where quantum algorithms for TDA perform best.Because quantum computers are not expected to solve #P-hard or NP-hard problems in subexponential time, our results imply that quantum algorithms for TDA offer only a polynomial advantage in the worst case.We support our claim by showing that the seminal quantum algorithm for TDA developed by Lloyd, Garnerone, and Zanardi achieves a quadratic speedup over the best-known classical approach in asymptotically almost all cases.Finally, we argue that an exponential quantum advantage can be recovered if the input data is given as a specification of simplices rather than as a list of vertices and edges.

PRX Quantum•Dec 28, 2023•17 citations
Different algorithms can be used for clustering purposes with data sets. On of these algorithms, uses topological features extracted from the data set to base the clusters on. The complexity of this algorithm is however exponential in the number of data points. Recently a quantum algorithm was proposed by Lloyd Garnerone and Zanardi with claimed polynomial complexity, hence an exponential improved over classical algorithms. However, we show that this algorithm in general cannot be used to compute these topological features in any dimension but the zeroth. We also give pointers on how to still use the algorithm for clustering purposes.
Persistent homology is a way to analyse the shape of a dataset rather than its semantics. This is done by assigning the dataset holes in different dimensions, borrowing this theory from the mathematical area of topology. The dataset is treated as being sampled from a topological space, which is in turn approximated at different resolutions. The persistent Betti numbers then count the number of holes in these spaces, registering for how long the holes persist as the resolution increases. Computing such features classically may prove costly, with some steps possibly requiring exponential time. In a 2016 paper, a polynomial time quantum algorithm for the approximation of persistent homology is promised. In this thesis it is shown these methods are generally incapable of uniquely determining the persistent Betti numbers in arbitrary dimensions. The algorithm does succeed in the zeroth dimension. After treating the prerequisites, the methods from this paper are explained, the above statements are proven, and finally the quantum algorithm is related to agglomerative hierarchical clustering and spectral clustering.
Extracting useful information from large data sets can be a daunting task. Topological methods for analyzing data sets provide a powerful technique for extracting such information. Persistent homology is a sophisticated tool for identifying such topological features -- connected components, holes, or voids -- and for determining how such features persist as the data is viewed at different scales. This paper provides quantum algorithms for calculating Betti numbers in persistent homology, and for finding eigenvectors and eigenvalues of the combinatorial Laplacian. The algorithms provide an exponential speedup over classical algorithms for topological data analysis.
Persistent homology, a powerful mathematical tool for data analysis, summarizes the shape of data through tracking topological features across changes in different scales. Classical algorithms for persistent homol-ogy are often constrained by running times and mem-ory requirements that grow exponentially on the number of data points. To surpass this problem, two quantum algorithms of persistent homology have been developed based on two different approaches. However, both of these quantum algorithms consider a data set in the form of a point cloud, which can be restrictive considering that many data sets come in the form of time series. In this paper, we alleviate this issue by establishing a quantum Takens's delay embedding algorithm, which turns a time series into a point cloud by considering a pertinent embedding into a higher dimensional space. Having this quantum transformation of time series to point clouds, then one may use a quantum persistent homology algorithm to extract the topological features from the point cloud associated with the original times series.
Extracting useful information from large data sets can be a daunting task. Topological methods for analysing data sets provide a powerful technique for extracting such information. Persistent homology is a sophisticated tool for identifying topological features and for determining how such features persist as the data is viewed at different scales. Here we present quantum machine learning algorithms for calculating Betti numbers--the numbers of connected components, holes and voids--in persistent homology, and for finding eigenvectors and eigenvalues of the combinatorial Laplacian. The algorithms provide an exponential speed-up over the best currently known classical algorithms for topological data analysis.
Given a data set with a notion of distance, such as a point cloud in Euclidean space, topological data analysis (TDA) uses techniques from algebraic topology and metric geometry to infer the topology of a hypothetical manifold from which the data are sampled. This inference is achieved by calculating topological invariants, some of which are difficult to compute classically. Meanwhile, quantum TDA utilizes quantum processes to extract the invariants used in making such inferences in an attempt to speed up the computations. Because applying transformations to the original classical dataset could alter the associated topological invariants, we investigate which quantum encodings would best preserve the invariants of the original dataset. This line of inquiry is distinct from standard approaches in quantum TDA, whose typical starting point is not from the classical dataset directly, but rather from the associated combinatorial objects, such as simplicial complexes, which typically demand a lot of resources to construct. We take the first step at a more direct approach by focusing on which quantum encodings acting directly on the data are admissible for applying quantum algorithms to extract topological features from classical datasets.
Quantum algorithms for topological data analysis (TDA) seem to provide an exponential advantage over the best classical approach while remaining immune to dequantization procedures and the data-loading problem.In this paper, we give complexity-theoretic evidence that the central task of TDA-estimating Betti numbers-is intractable even for quantum computers.Specifically, we prove that the problem of computing Betti numbers exactly is #P-hard, while the problem of approximating Betti numbers up to multiplicative error is NP-hard.Moreover, both problems retain their hardness if restricted to the regime where quantum algorithms for TDA perform best.Because quantum computers are not expected to solve #P-hard or NP-hard problems in subexponential time, our results imply that quantum algorithms for TDA offer only a polynomial advantage in the worst case.We support our claim by showing that the seminal quantum algorithm for TDA developed by Lloyd, Garnerone, and Zanardi achieves a quadratic speedup over the best-known classical approach in asymptotically almost all cases.Finally, we argue that an exponential quantum advantage can be recovered if the input data is given as a specification of simplices rather than as a list of vertices and edges.