Strategies for simulating time evolution of Hamiltonian lattice field theories

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Main Authors: Hariprakash, Siddharth, Modi, Neel S., Kreshchuk, Michael, Kane, Christopher F., Bauer, Christian W
Format: Preprint
Published: 2023
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author Hariprakash, Siddharth
Modi, Neel S.
Kreshchuk, Michael
Kane, Christopher F.
Bauer, Christian W
author_facet Hariprakash, Siddharth
Modi, Neel S.
Kreshchuk, Michael
Kane, Christopher F.
Bauer, Christian W
contents Simulating the time evolution of quantum field theories given some Hamiltonian $H$ requires developing algorithms for implementing the unitary operator e^{-iHt}. A variety of techniques exist that accomplish this task, with the most common technique used so far being Trotterization, which is a special case of the application of a product formula. However, other techniques exist that promise better asymptotic scaling in certain parameters of the theory being simulated, the most efficient of which are based on the concept of block encoding. In this work we study the performance of such algorithms in simulating lattice field theories. We derive and compare the asymptotic gate complexities of several commonly used simulation techniques in application to Hamiltonian Lattice Field Theories. Using the scalar ϕ^4 theory as a test, we also perform numerical studies and compare the gate costs required by Product Formulas and Signal Processing based techniques to simulate time evolution. For the latter, we use the the Linear Combination of Unitaries construction augmented with the Quantum Fourier Transform circuit to switch between the field and momentum eigenbases, which leads to immediate order-of-magnitude improvement in the cost of preparing the block encoding. The paper also includes a pedagogical review of utilized techniques, in particular Product Formulas, LCU, Qubitization, QSP, as well as a technique we call HHKL based on its inventors' names.
format Preprint
id arxiv_https___arxiv_org_abs_2312_11637
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Strategies for simulating time evolution of Hamiltonian lattice field theories
Hariprakash, Siddharth
Modi, Neel S.
Kreshchuk, Michael
Kane, Christopher F.
Bauer, Christian W
Quantum Physics
High Energy Physics - Lattice
High Energy Physics - Phenomenology
Simulating the time evolution of quantum field theories given some Hamiltonian $H$ requires developing algorithms for implementing the unitary operator e^{-iHt}. A variety of techniques exist that accomplish this task, with the most common technique used so far being Trotterization, which is a special case of the application of a product formula. However, other techniques exist that promise better asymptotic scaling in certain parameters of the theory being simulated, the most efficient of which are based on the concept of block encoding. In this work we study the performance of such algorithms in simulating lattice field theories. We derive and compare the asymptotic gate complexities of several commonly used simulation techniques in application to Hamiltonian Lattice Field Theories. Using the scalar ϕ^4 theory as a test, we also perform numerical studies and compare the gate costs required by Product Formulas and Signal Processing based techniques to simulate time evolution. For the latter, we use the the Linear Combination of Unitaries construction augmented with the Quantum Fourier Transform circuit to switch between the field and momentum eigenbases, which leads to immediate order-of-magnitude improvement in the cost of preparing the block encoding. The paper also includes a pedagogical review of utilized techniques, in particular Product Formulas, LCU, Qubitization, QSP, as well as a technique we call HHKL based on its inventors' names.
title Strategies for simulating time evolution of Hamiltonian lattice field theories
topic Quantum Physics
High Energy Physics - Lattice
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2312.11637