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Simulating quantum circuits using classical computers lets us analyse the inner workings of quantum algorithms. The most complete type of simulation, strong simulation, is believed to be generally inefficient. Nevertheless, several…

Quantum Physics · Physics 2013-02-25 T. H. Johnson , J. D. Biamonte , S. R. Clark , D. Jaksch

Cloud-accessible quantum processors enable direct execution of quantum algorithms on heterogeneous hardware platforms. Unlike classical systems, however, identical quantum circuits may exhibit substantially different behavior across devices…

Quantum Physics · Physics 2026-01-12 Askar Oralkhan , Temirlan Zhaxalykov

We introduce a structured quantum search algorithm that leverages entanglement maps and a fixed-point method to minimize oracle query complexity in unsorted datasets. By partitioning qubits into rows based on their entanglement order, the…

Quantum Physics · Physics 2025-07-22 Yash Prabhat , Snigdha Thakur , Ankur Raina

Quantum circuit complexity is a fundamental concept whose importance permeates quantum information, computation, many-body physics and high-energy physics. While extensively studied in closed systems, its characterization and behaviors in…

Quantum Physics · Physics 2025-08-28 Zhenyu Du , Zi-Wen Liu , Xiongfeng Ma

Quantum computing leverages quantum mechanics to address computational problems in ways that differ fundamentally from classical approaches. While current quantum hardware remains error-prone and limited in scale, Variational Quantum…

Quantum Physics · Physics 2025-09-16 Michael Kölle , Simon Salfer , Tobias Rohe , Philipp Altmann , Claudia Linnhoff-Popien

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

Quantum computing can empower machine learning models by enabling kernel machines to leverage quantum kernels for representing similarity measures between data. Quantum kernels are able to capture relationships in the data that are not…

The current era of quantum computing has yielded several algorithms that promise high computational efficiency. While the algorithms are sound in theory and can provide potentially exponential speedup, there is little guidance on how to…

Quantum Physics · Physics 2023-10-13 Ankit Kulshrestha , Danylo Lykov , Ilya Safro , Yuri Alexeev

We examine the use of adiabatic quantum algorithms to solve structured, or nested, search problems. We construct suitable time dependent Hamiltonians and derive the computation times for a general class of nested searches involving n…

Quantum Physics · Physics 2007-05-23 Daria Ahrensmeier , Saurya Das , Randy Kobes , Gabor Kunstatter , Haitham Zaraket

Quantum cryptography is going to find practically useful applications. Recently some first quantum cryptographic solutions became available on the market. For clients it is important to be able to compare the quality and properties of the…

Quantum Physics · Physics 2013-04-24 A. S. Trushechkin , I. V. Volovich

A quantum algorithm is known that solves an unstructured search problem in a number of iterations of order $\sqrt{d}$, where $d$ is the dimension of the search space, whereas any classical algorithm necessarily scales as $O(d)$. It is shown…

Quantum Physics · Physics 2009-10-31 N. J. Cerf , L. K. Grover , C. P. Williams

Quantum spatial search has been widely studied with most of the study focusing on quantum walk algorithms. We show that quantum walk algorithms are extremely sensitive to systematic errors. We present a recursive algorithm which offers…

Quantum Physics · Physics 2016-02-15 Avatar Tulsi

Variational quantum algorithms (VQAs) are expected to be a path to quantum advantages on noisy intermediate-scale quantum devices. However, both empirical and theoretical results exhibit that the deployed ansatz heavily affects the…

Quantum Physics · Physics 2022-05-31 Yuxuan Du , Tao Huang , Shan You , Min-Hsiu Hsieh , Dacheng Tao

Previously, the author has developed a framework within which to quantify and compare the resources consumed during computational-especially unconventional computational-processes (adding to the familiar resources of run-time and memory…

Cryptography and Security · Computer Science 2013-04-17 Ed Blakey

Quantum hashing is a useful technique that allows us to construct memory-efficient algorithms and secure quantum protocols. First, we present a circuit that implements the phase form of quantum hashing using $2^{n-1}$ CNOT gates, where n is…

Quantum Physics · Physics 2025-07-10 Ilnar Zinnatullin , Kamil Khadiev

Quantum complexity measures the difficulty of obtaining a given state starting from a typically unentangled state. In this work, we show that complexity, when defined through the minimization of a Riemannian cost functional over the…

Quantum Physics · Physics 2025-06-05 Nadir Samos Sáenz de Buruaga

Quantum simulations of chemistry in first quantization offer important advantages over approaches in second quantization including faster convergence to the continuum limit and the opportunity for practical simulations outside the…

Quantum Physics · Physics 2021-12-02 Yuan Su , Dominic W. Berry , Nathan Wiebe , Nicholas Rubin , Ryan Babbush

Quantum computing has made significant progress in recent years, attracting immense interest not only in research laboratories but also in various industries. However, the application of quantum computing to solve real-world problems is…

Quantum Physics · Physics 2025-05-26 Darya Martyniuk , Johannes Jung , Adrian Paschke

The hope of the quantum computing field is that quantum architectures are able to scale up and realize fault-tolerant quantum computing. Due to engineering challenges, such ''cheap'' error correction may be decades away. In the meantime, we…

Quantum Physics · Physics 2025-02-17 Rutuja Kshirsagar , Amara Katabarwa , Peter D. Johnson

Unstructured search remains as one of the significant challenges in computer science, as classical search algorithms become increasingly impractical for large-scale systems due to their linear time complexity. Quantum algorithms, notably…

Quantum Physics · Physics 2025-05-22 Harishankar Mishra , Asvija Balasubramanyam , Gudapati Naresh Raghava