Stochastic emulation of quantum algorithms

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 qubits at the same time. The former aspect renders the direct cl...

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Main Authors: Daniel Braun, Ronny Müller
Format: Article
Language:English
Published: IOP Publishing 2022-01-01
Series:New Journal of Physics
Subjects:
Online Access:https://doi.org/10.1088/1367-2630/ac4b0f
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author Daniel Braun
Ronny Müller
author_facet Daniel Braun
Ronny Müller
author_sort Daniel Braun
collection DOAJ
description 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 qubits at the same time. The former aspect renders the direct classical simulation of quantum algorithms difficult. Here we introduce higher-order partial derivatives of a probability distribution of particle positions as a new object that shares these basic properties of quantum mechanical states needed for a quantum algorithm. Discretization of the positions allows one to represent the quantum mechanical state of n _bit qubits by 2( n _bit + 1) classical stochastic bits. Based on this, we demonstrate many-particle interference and representation of pure entangled quantum states via derivatives of probability distributions and find the universal set of stochastic maps that correspond to the quantum gates in a universal gate set. We prove that the propagation via the stochastic map built from those universal stochastic maps reproduces up to a prefactor exactly the evolution of the quantum mechanical state with the corresponding quantum algorithm, leading to an automated translation of a quantum algorithm to a stochastic classical algorithm. We implement several well-known quantum algorithms, analyse the scaling of the needed number of realizations with the number of qubits, and highlight the role of destructive interference for the cost of the emulation.
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spelling doaj.art-8823d2700b50468e93e756ca5c975a682023-08-09T14:17:46ZengIOP PublishingNew Journal of Physics1367-26302022-01-0124202302810.1088/1367-2630/ac4b0fStochastic emulation of quantum algorithmsDaniel Braun0https://orcid.org/0000-0001-8598-2039Ronny Müller1https://orcid.org/0000-0002-4276-9657Eberhard-Karls-Universität Tübingen, Institut für Theoretische Physik , 72076 Tübingen, GermanyEberhard-Karls-Universität Tübingen, Institut für Theoretische Physik , 72076 Tübingen, GermanyQuantum 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 qubits at the same time. The former aspect renders the direct classical simulation of quantum algorithms difficult. Here we introduce higher-order partial derivatives of a probability distribution of particle positions as a new object that shares these basic properties of quantum mechanical states needed for a quantum algorithm. Discretization of the positions allows one to represent the quantum mechanical state of n _bit qubits by 2( n _bit + 1) classical stochastic bits. Based on this, we demonstrate many-particle interference and representation of pure entangled quantum states via derivatives of probability distributions and find the universal set of stochastic maps that correspond to the quantum gates in a universal gate set. We prove that the propagation via the stochastic map built from those universal stochastic maps reproduces up to a prefactor exactly the evolution of the quantum mechanical state with the corresponding quantum algorithm, leading to an automated translation of a quantum algorithm to a stochastic classical algorithm. We implement several well-known quantum algorithms, analyse the scaling of the needed number of realizations with the number of qubits, and highlight the role of destructive interference for the cost of the emulation.https://doi.org/10.1088/1367-2630/ac4b0fquantum algorithmstochastic matricesclassical entanglementquantum interference
spellingShingle Daniel Braun
Ronny Müller
Stochastic emulation of quantum algorithms
New Journal of Physics
quantum algorithm
stochastic matrices
classical entanglement
quantum interference
title Stochastic emulation of quantum algorithms
title_full Stochastic emulation of quantum algorithms
title_fullStr Stochastic emulation of quantum algorithms
title_full_unstemmed Stochastic emulation of quantum algorithms
title_short Stochastic emulation of quantum algorithms
title_sort stochastic emulation of quantum algorithms
topic quantum algorithm
stochastic matrices
classical entanglement
quantum interference
url https://doi.org/10.1088/1367-2630/ac4b0f
work_keys_str_mv AT danielbraun stochasticemulationofquantumalgorithms
AT ronnymuller stochasticemulationofquantumalgorithms