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Quantum algorithms profit from the interference of quantum states in an exponentially large Hilbert space and the fact that unitary transformations on that Hilbert space can be broken down to universal gates that act only on one or two…

Quantum Physics · Physics 2022-03-14 Daniel Braun , Ronny Müller

The solving of linear systems provides a rich area to investigate the use of nearer-term, noisy, intermediate-scale quantum computers. In this work, we discuss hybrid quantum-classical algorithms for skewed linear systems for…

Quantum Physics · Physics 2021-04-28 Bujiao Wu , Maharshi Ray , Liming Zhao , Xiaoming Sun , Patrick Rebentrost

Continuous-time stochastic processes pervade everyday experience, and the simulation of models of these processes is of great utility. Classical models of systems operating in continuous-time must typically track an unbounded amount of…

Quantum Physics · Physics 2018-03-05 Thomas J. Elliott , Mile Gu

We show on the example of the Arnold cat map that classical chaotic systems can be simulated with exponential efficiency on a quantum computer. Although classical computer errors grow exponentially with time, the quantum algorithm with…

Quantum Physics · Physics 2016-09-08 B. Georgeot , D. L. Shepelyansky

We describe an approach for characterizing the process of quantum gates using quantum process tomography, by first modeling them in an extended Hilbert space, which includes non-qubit degrees of freedom. To prevent unphysical processes from…

Quantum Physics · Physics 2008-11-26 Peter P. Rohde , G. J. Pryde , J. L. O'Brien , Timothy C. Ralph

We present characterisations of "exact" gap-definable classes, in terms of indeterministic models of computation which slightly modify the standard model of quantum computation. This follows on work of Aaronson [arXiv:quant-ph/0412187], who…

Computational Complexity · Computer Science 2015-09-28 Niel de Beaudrap

This paper describes a novel approach to emulate a universal quantum computer with a wholly classical system, one that uses a signal of bounded duration and amplitude to represent an arbitrary quantum state. The signal may be of any…

According to the statistical interpretation of quantum theory, quantum computers form a distinguished class of probabilistic machines (PMs) by encoding n qubits in 2n pbits (random binary variables). This raises the possibility of a…

Quantum Physics · Physics 2007-05-23 P. Gralewicz

A classical state-preparation device cannot generate states in relative superposition. We introduce classical models in which devices that are individually unable to generate states with relative superposition can be stochastically…

Quantum Physics · Physics 2026-02-03 Gabriele Cobucci , Alexander Bernal , Martin J. Renner , Armin Tavakoli

We describe how one may go about performing quantum computation with arbitrary "quantum stuff", as long as it has some basic physical properties. Imagine a long strip of stuff, equipped with regularly spaced wires to provide input settings…

Quantum Physics · Physics 2019-12-03 Lucien Hardy , Adam G. M. Lewis

We show how to realize a general quantum circuit involving gates between arbitrary pairs of qubits by means of geometrically local quantum operations and efficient classical computation. We prove that circuit-level local stochastic noise…

Quantum Physics · Physics 2024-02-22 Shin Ho Choe , Robert Koenig

Quantum computations promise the ability to solve problems intractable in the classical setting. Restricting the types of computations considered often allows to establish a provable theoretical advantage by quantum computations, and later…

Quantum Physics · Physics 2021-11-19 Dmitri Maslov , Jin-Sung Kim , Sergey Bravyi , Theodore J. Yoder , Sarah Sheldon

Despite rapid recent advances in quantum machine learning, the field is in many ways stuck. Existing approaches can exhibit serious limitations, and we still lack learning frameworks that are simple, interpretable, scalable, and naturally…

According to the stochastic-quantum correspondence, a quantum system can be understood as a stochastic process unfolding in an old-fashioned configuration space based on ordinary notions of probability and `indivisible' stochastic laws,…

Quantum Physics · Physics 2025-07-30 Jacob A. Barandes

Although the emergence of a fully-functional quantum computer may still be far away from today, in the near future, it is possible to have medium-size, special-purpose, quantum devices that can perform computational tasks not efficiently…

Quantum Physics · Physics 2017-06-28 Man-Hong Yung , Xun Gao

A formalism is developed for describing approximate classical behaviour in finite (but possibly large) quantum systems. This is done in terms of a structure common to classical and quantum mechanics, viz. a Poisson space with a transition…

Quantum Physics · Physics 2015-06-26 N. P. Landsman

We consider the task of deciding whether an unknown qubit state falls in a prescribed neighborhood of a reference state. We assume that several copies of the unknown state are given and apply a unitary operation pairwise on them combined…

Quantum Physics · Physics 2018-08-27 Orsolya Kálmán , Tamás Kiss

Quantum mechanics is widely regarded as a complete theory, yet we argue it is a tractable projection of a deeper, computationally-inaccessible classical variational structure. By analyzing the coupled partial differential equations of the…

General Physics · Physics 2026-01-26 Khaled Mnaymneh

"Quantum mechanics must be regarded as open systems. On one hand, this is due to the fact that, like in classical physics, any realistic system is subjected to a coupling to an uncontrollable environment which influences it in a…

Quantum Physics · Physics 2007-05-23 S. Nicolosi

Understanding which subclasses of quantum circuits are efficiently classically simulable is fundamental to delineating the boundary between classical and quantum computation. In this context, it is well known that certain tasks based on…

Quantum Physics · Physics 2026-03-16 Su Yeon Chang , Martin Larocca , M. Cerezo