Optimal compression of constrained quantum time evolution

Fuente: arXiv
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Hauptverfasser: Tepaske, Maurits S. J., Luitz, David J., Hahn, Dominik
Format: Preprint
Veröffentlicht: 2023
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author Tepaske, Maurits S. J.
Luitz, David J.
Hahn, Dominik
author_facet Tepaske, Maurits S. J.
Luitz, David J.
Hahn, Dominik
contents The time evolution of quantum many-body systems is one of the most promising applications for near-term quantum computers. However, the utility of current quantum devices is strongly hampered by the proliferation of hardware errors. The minimization of the circuit depth for a given quantum algorithm is therefore highly desirable, since shallow circuits generally are less vulnerable to decoherence. Recently, it was shown that variational circuits are a promising approach to outperform current state-of-the-art methods such as Trotter decomposition, although the optimal choice of parameters is a computationally demanding task. In this work, we demonstrate a simplification of the variational optimization of circuits implementing the time evolution operator of local Hamiltonians by directly encoding constraints of the physical system under consideration. We study the expressibility of such constrained variational circuits for different models and constraints. Our results show that the encoding of constraints allows a reduction of optimization cost by more than one order of magnitude and scalability to arbitrary large system sizes, without loosing accuracy in most systems. Furthermore, we discuss the exceptions in locally-constrained systems and provide an explanation by means of an restricted lightcone width after incorporating the constraints into the circuits.
format Preprint
id arxiv_https___arxiv_org_abs_2311_06347
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Optimal compression of constrained quantum time evolution
Tepaske, Maurits S. J.
Luitz, David J.
Hahn, Dominik
Quantum Physics
Strongly Correlated Electrons
The time evolution of quantum many-body systems is one of the most promising applications for near-term quantum computers. However, the utility of current quantum devices is strongly hampered by the proliferation of hardware errors. The minimization of the circuit depth for a given quantum algorithm is therefore highly desirable, since shallow circuits generally are less vulnerable to decoherence. Recently, it was shown that variational circuits are a promising approach to outperform current state-of-the-art methods such as Trotter decomposition, although the optimal choice of parameters is a computationally demanding task. In this work, we demonstrate a simplification of the variational optimization of circuits implementing the time evolution operator of local Hamiltonians by directly encoding constraints of the physical system under consideration. We study the expressibility of such constrained variational circuits for different models and constraints. Our results show that the encoding of constraints allows a reduction of optimization cost by more than one order of magnitude and scalability to arbitrary large system sizes, without loosing accuracy in most systems. Furthermore, we discuss the exceptions in locally-constrained systems and provide an explanation by means of an restricted lightcone width after incorporating the constraints into the circuits.
title Optimal compression of constrained quantum time evolution
topic Quantum Physics
Strongly Correlated Electrons
url https://arxiv.org/abs/2311.06347