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One-way functions are fundamental to classical cryptography and their existence remains a longstanding problem in computational complexity theory. Recently, a provable quantum one-way function has been identified, which maintains its…

Quantum Physics · Physics 2024-08-27 Hua-Lei Yin

Universal quantum computation can be realised using both continuous-time and discrete-time quantum walks. We present a version based on single particle discrete-time quantum walk to realize multi-qubit computation tasks. The scalability of…

Quantum Physics · Physics 2023-08-21 Prateek Chawla , Shivani Singh , Aman Agarwal , Sarvesh Srinivasan , C. M. Chandrashekar

Quantum data re-uploading has proved powerful for classical inputs, where repeatedly encoding features into a small circuit yields universal function approximation. Extending this idea to quantum inputs remains underexplored, as the…

Quantum Physics · Physics 2025-11-12 Hyunho Cha , Daniel K. Park , Jungwoo Lee

Most quantum computer realizations require the ability to apply local fields and tune the couplings between qubits, in order to realize single bit and two bit gates which are necessary for universal quantum computation. We present a scheme…

Quantum Physics · Physics 2009-11-07 Xingxiang Zhou , Zheng-Wei Zhou , Guang-Can Guo , Marc J. Feldman

In a recent preprint by Deutsch et al. [1995] the authors suggest the possibility of polynomial approximability of arbitrary unitary operations on $n$ qubits by 2-qubit unitary operations. We address that comment by proving strong lower…

Quantum Physics · Physics 2008-02-03 E. Knill

Complex quantum circuits are constituted by combinations of quantum subroutines. The computation is possible as long as the quantum data encoding is consistent throughout the circuit. Despite its fundamental importance, the formalization of…

Emerging Technologies · Computer Science 2025-11-10 Gabriele Agliardi , Enrico Prati

Superconducting quantum circuit is a promising system for building quantum computer. With this system we demonstrate the universal quantum computations, including the preparing of initial states, the single-qubit operations, the two-qubit…

Quantum Physics · Physics 2018-09-06 Nian-Quan Jiang , Yao Chen , Chuanbing Cai , Ming-FengWang , Junwang Tang

Quantum computation represents a computational paradigm whose distinctive attributes confer the ability to devise algorithms with asymptotic performance levels significantly superior to those achievable via classical computation. Recent…

Data Structures and Algorithms · Computer Science 2023-08-24 Domenico Cantone , Simone Faro , Arianna Pavone , Caterina Viola

For a machine learning paradigm to be generally applicable, it should have the property of universal approximation, that is, it should be able to approximate any target function to any desired degree of accuracy. In variational quantum…

Quantum Physics · Physics 2026-01-30 Sydney Leither , Michael Kubal , Sonika Johri

Quantum computers provide a fundamentally new computing paradigm that promises to revolutionize our ability to solve broad classes of problems. Surprisingly, the basic mathematical structures of gate-based quantum computing, such as unitary…

Quantum Physics · Physics 2019-08-20 Brian R. La Cour , S. Andrew Lanham , Corey I. Ostrove

Quantum computing is fast evolving as a technology due to recent advances in hardware, software, as well as the development of promising applications. To use this technology for solving specific problems, a suitable quantum algorithm has to…

Quantum Physics · Physics 2024-06-25 Nils Quetschlich , Lukas Burgholzer , Robert Wille

We show that universal quantum computation can be achieved in the standard pure-state circuit model while, at any time, the entanglement entropy of all bipartitions is small---even tending to zero with growing system size. The result is…

Quantum Physics · Physics 2013-04-11 Maarten Van den Nest

We demonstrate the applicability of a universal gate set in the parity encoding, which is a dual to the standard gate model, by exploring several quantum gate algorithms such as the quantum Fourier transform and quantum addition. Embedding…

Quantum Physics · Physics 2022-11-03 Michael Fellner , Anette Messinger , Kilian Ender , Wolfgang Lechner

Quantum computing relies on processing information within a quantum system with many continuous degrees of freedom. The practical implementation of this idea requires complete control over all of the 2^n independent amplitudes of a…

Condensed Matter · Physics 2007-05-23 M. I. Dyakonov

We give quantum circuits that simulate an arbitrary two-qubit unitary operator up to global phase. For several quantum gate libraries we prove that gate counts are optimal in worst and average cases. Our lower and upper bounds compare…

Quantum Physics · Physics 2013-05-29 Vivek V. Shende , Igor L. Markov , Stephen S. Bullock

We present a number of quantum computing patterns that build on top of fundamental algorithms, that can be applied to solving concrete, NP-hard problems. In particular, we introduce the concept of a quantum dictionary as a summation of…

Quantum computation offers the potential to solve fundamental yet otherwise intractable problems across a range of active fields of research. Recently, universal quantum-logic gate sets - the building blocks for a quantum computer - have…

Parameterized quantum circuits have been extensively used as the basis for machine learning models in regression, classification, and generative tasks. For supervised learning, their expressivity has been thoroughly investigated and several…

Quantum Physics · Physics 2026-05-20 Alice Barthe , Michele Grossi , Sofia Vallecorsa , Jordi Tura , Vedran Dunjko

Quantum walks, the quantum mechanical counterpart of classical random walks, is an advanced tool for building quantum algorithms that has been recently shown to constitute a universal model of quantum computation. Quantum walks is now a…

Quantum Physics · Physics 2012-10-01 Salvador E. Venegas-Andraca

Photonic quantum computing is one of the leading approaches to universal quantum computation. However, large-scale implementation of photonic quantum computing has been hindered by its intrinsic difficulties, such as probabilistic…

Quantum Physics · Physics 2019-06-17 Shuntaro Takeda , Akira Furusawa