Importance sampling for stochastic quantum simulations

Simulating many-body quantum systems is a promising task for quantum computers. However, the depth of most algorithms, such as product formulas, scales with the number of terms in the Hamiltonian, and can therefore be challenging to implement on near-term, as well as early fault-tolerant quantum dev...

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Main Authors: Oriel Kiss, Michele Grossi, Alessandro Roggero
Format: Article
Language:English
Published: Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften 2023-04-01
Series:Quantum
Online Access:https://quantum-journal.org/papers/q-2023-04-13-977/pdf/
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author Oriel Kiss
Michele Grossi
Alessandro Roggero
author_facet Oriel Kiss
Michele Grossi
Alessandro Roggero
author_sort Oriel Kiss
collection DOAJ
description Simulating many-body quantum systems is a promising task for quantum computers. However, the depth of most algorithms, such as product formulas, scales with the number of terms in the Hamiltonian, and can therefore be challenging to implement on near-term, as well as early fault-tolerant quantum devices. An efficient solution is given by the stochastic compilation protocol known as qDrift, which builds random product formulas by sampling from the Hamiltonian according to the coefficients. In this work, we unify the qDrift protocol with importance sampling, allowing us to sample from arbitrary probability distributions, while controlling both the bias, as well as the statistical fluctuations. We show that the simulation cost can be reduced while achieving the same accuracy, by considering the individual simulation cost during the sampling stage. Moreover, we incorporate recent work on composite channel and compute rigorous bounds on the bias and variance, showing how to choose the number of samples, experiments, and time steps for a given target accuracy. These results lead to a more efficient implementation of the qDrift protocol, both with and without the use of composite channels. Theoretical results are confirmed by numerical simulations performed on a lattice nuclear effective field theory.
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spelling doaj.art-f5a8b61bdc0644deb2666d54db0c13752023-04-13T12:37:08ZengVerein zur Förderung des Open Access Publizierens in den QuantenwissenschaftenQuantum2521-327X2023-04-01797710.22331/q-2023-04-13-97710.22331/q-2023-04-13-977Importance sampling for stochastic quantum simulationsOriel KissMichele GrossiAlessandro RoggeroSimulating many-body quantum systems is a promising task for quantum computers. However, the depth of most algorithms, such as product formulas, scales with the number of terms in the Hamiltonian, and can therefore be challenging to implement on near-term, as well as early fault-tolerant quantum devices. An efficient solution is given by the stochastic compilation protocol known as qDrift, which builds random product formulas by sampling from the Hamiltonian according to the coefficients. In this work, we unify the qDrift protocol with importance sampling, allowing us to sample from arbitrary probability distributions, while controlling both the bias, as well as the statistical fluctuations. We show that the simulation cost can be reduced while achieving the same accuracy, by considering the individual simulation cost during the sampling stage. Moreover, we incorporate recent work on composite channel and compute rigorous bounds on the bias and variance, showing how to choose the number of samples, experiments, and time steps for a given target accuracy. These results lead to a more efficient implementation of the qDrift protocol, both with and without the use of composite channels. Theoretical results are confirmed by numerical simulations performed on a lattice nuclear effective field theory.https://quantum-journal.org/papers/q-2023-04-13-977/pdf/
spellingShingle Oriel Kiss
Michele Grossi
Alessandro Roggero
Importance sampling for stochastic quantum simulations
Quantum
title Importance sampling for stochastic quantum simulations
title_full Importance sampling for stochastic quantum simulations
title_fullStr Importance sampling for stochastic quantum simulations
title_full_unstemmed Importance sampling for stochastic quantum simulations
title_short Importance sampling for stochastic quantum simulations
title_sort importance sampling for stochastic quantum simulations
url https://quantum-journal.org/papers/q-2023-04-13-977/pdf/
work_keys_str_mv AT orielkiss importancesamplingforstochasticquantumsimulations
AT michelegrossi importancesamplingforstochasticquantumsimulations
AT alessandroroggero importancesamplingforstochasticquantumsimulations