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Artificial Intelligence has achieved remarkable success across diverse application domains. However, its vulnerability to adversarial attacks poses significant challenges to reliability, security, and trustworthiness. Adversarial machine…

Cryptography and Security · Computer Science 2026-05-29 Jaydip Sen

The quantum adversary method is one of the most versatile lower-bound methods for quantum algorithms. We show that all known variants of this method are equivalent: spectral adversary (Barnum, Saks, and Szegedy, 2003), weighted adversary…

Quantum Physics · Physics 2007-05-23 Robert Spalek , Mario Szegedy

We show that the quantum query complexity of detecting if an $n$-vertex graph contains a triangle is $O(n^{9/7})$. This improves the previous best algorithm of Belovs making $O(n^{35/27})$ queries. For the problem of determining if an…

Quantum Physics · Physics 2012-10-04 Troy Lee , Frederic Magniez , Miklos Santha

Proximity graph-based methods have emerged as a leading paradigm for approximate nearest neighbor (ANN) search in the system community. This paper presents fresh insights into the theoretical foundation of these methods. We describe an…

Data Structures and Algorithms · Computer Science 2025-09-10 Shangqi Lu , Yufei Tao

We construct a new quantum algorithm for the graph collision problem; that is, the problem of deciding whether the set of marked vertices contains a pair of adjacent vertices in a known graph G. The query complexity of our algorithm is…

Quantum Physics · Physics 2012-04-09 Dmitry Gavinsky , Tsuyoshi Ito

Quantum walks are at the heart of modern quantum technologies. They allow to deal with quantum transport phenomena and are an advanced tool for constructing novel quantum algorithms. Quantum walks on graphs are fundamentally different from…

Quantum Physics · Physics 2019-12-18 Alexey A. Melnikov , Leonid E. Fedichkin , Alexander Alodjants

The main reason for query model's prominence in complexity theory and quantum computing is the presence of concrete lower bounding techniques: polynomial and adversary method. There have been considerable efforts to give lower bounds using…

Quantum Physics · Physics 2024-02-20 Rajat Mittal , Sanjay S Nair , Sunayana Patro

The quantum walk is a powerful tool to develop quantum algorithms, which usually are based on searching for a vertex in a graph with multiple marked vertices, Ambainis's quantum algorithm for solving the element distinctness problem being…

Quantum Physics · Physics 2022-12-21 G. A. Bezerra , P. H. G. Lugão , R. Portugal

We present quantum algorithms for various problems related to graph connectivity. We give simple and query-optimal algorithms for cycle detection and odd-length cycle detection (bipartiteness) using a reduction to st-connectivity.…

Quantum Physics · Physics 2019-10-03 Kai DeLorenzo , Shelby Kimmel , R. Teal Witter

We use quantum walks to construct a new quantum algorithm for element distinctness and its generalization. For element distinctness (the problem of finding two equal items among N given items), we get an O(N^{2/3}) query quantum algorithm.…

Quantum Physics · Physics 2014-05-01 Andris Ambainis

We present an extension to the quantum walk search framework that facilitates quantum walks with nested updates. We apply it to give a quantum walk algorithm for 3-Distinctness with query complexity ~O(n^{5/7}), matching the best known…

Quantum Physics · Physics 2013-03-01 Andrew M. Childs , Stacey Jeffery , Robin Kothari , Frederic Magniez

We present a quantum algorithm solving the $k$-distinctness problem in $O(n^{1-2^{k-2}/(2^k-1)})$ queries with a bounded error. This improves the previous $O(n^{k/(k+1)})$-query algorithm by Ambainis. The construction uses a modified…

Quantum Physics · Physics 2012-08-10 Aleksandrs Belovs

In this paper, we consider the parameterized quantum query complexity for graph problems. We design parameterized quantum query algorithms for $k$-vertex cover and $k$-matching problems, and present lower bounds on the parameterized quantum…

Quantum Physics · Physics 2024-08-08 Tatsuya Terao , Ryuhei Mori

As quantum computing continues to advance, the development of quantum-secure neural networks is crucial to prevent adversarial attacks. This paper proposes three quantum-secure design principles: (1) using post-quantum cryptography, (2)…

Quantum Physics · Physics 2026-04-14 Eric Yocam , Anthony Rizi , Mahesh Kamepalli , Varghese Vaidyan , Yong Wang , Gurcan Comert

Quantum algorithms for several problems in graph theory are considered. Classical algorithms for finding the lowest weight path between two points in a graph and for finding a minimal weight spanning tree involve searching over some space.…

Quantum Physics · Physics 2007-05-23 Mark Heiligman

We present two new quantum algorithms that either find a triangle (a copy of $K_{3}$) in an undirected graph $G$ on $n$ nodes, or reject if $G$ is triangle free. The first algorithm uses combinatorial ideas with Grover Search and makes…

Quantum Physics · Physics 2007-05-23 Frederic Magniez , Miklos Santha , Mario Szegedy

We initiate a systematic study of the time complexity of quantum divide and conquer algorithms for classical problems. We establish generic conditions under which search and minimization problems with classical divide and conquer algorithms…

Quantum Physics · Physics 2025-12-03 Jonathan Allcock , Jinge Bao , Aleksandrs Belovs , Troy Lee , Miklos Santha

Adversarial attacks to graph analytics are gaining increased attention. To date, two lines of countermeasures have been proposed to resist various graph adversarial attacks from the perspectives of either graph per se or graph neural…

Machine Learning · Computer Science 2025-05-21 Xinxin Fan , Wenxiong Chen , Mengfan Li , Wenqi Wei , Ling Liu

In this paper, we initiate the study of quantum algorithms in the Graph Drawing research area. We focus on two foundational drawing standards: 2-level drawings and book layouts. Concerning $2$-level drawings, we consider the problems of…

Data Structures and Algorithms · Computer Science 2023-07-18 Susanna Caroppo , Giordano Da Lozzo , Giuseppe Di Battista

Graph neural networks, a popular class of models effective in a wide range of graph-based learning tasks, have been shown to be vulnerable to adversarial attacks. While the majority of the literature focuses on such vulnerability in…

Machine Learning · Statistics 2021-11-05 Xingchen Wan , Henry Kenlay , Binxin Ru , Arno Blaas , Michael A. Osborne , Xiaowen Dong