Strong error bounds for Trotter and strang-splittings and their implications for quantum chemistry

Efficient error estimates for the Trotter product formula are central in quantum computing, mathematical physics, and numerical simulations. However, the Trotter error's dependency on the input state and its application to unbounded operators remains unclear. Here, we present a general theory f...

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Main Authors: Daniel Burgarth, Paolo Facchi, Alexander Hahn, Mattias Johnsson, Kazuya Yuasa
Format: Article
Language:English
Published: American Physical Society 2024-11-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.6.043155
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author Daniel Burgarth
Paolo Facchi
Alexander Hahn
Mattias Johnsson
Kazuya Yuasa
author_facet Daniel Burgarth
Paolo Facchi
Alexander Hahn
Mattias Johnsson
Kazuya Yuasa
author_sort Daniel Burgarth
collection DOAJ
description Efficient error estimates for the Trotter product formula are central in quantum computing, mathematical physics, and numerical simulations. However, the Trotter error's dependency on the input state and its application to unbounded operators remains unclear. Here, we present a general theory for error estimation, including higher-order product formulas, with explicit input state dependency. Our approach overcomes two limitations of the existing operator-norm estimates in the literature. First, previous bounds are too pessimistic as they quantify the worst-case scenario. Second, previous bounds become trivial for unbounded operators and cannot be applied to a wide class of Trotter scenarios, including atomic and molecular Hamiltonians. Our method enables analytical treatment of Trotter errors in chemistry simulations, illustrated through a case study on the hydrogen atom. Our findings reveal the following: (i) for states with fat-tailed energy distribution, such as low-angular-momentum states of the hydrogen atom, the Trotter error scales worse than expected (sublinearly) in the number of Trotter steps; (ii) certain states do not admit an advantage in the scaling from higher-order Trotterization and, thus, the higher-order Trotter hierarchy breaks down for these states, including the hydrogen atom's ground state; (iii) the scaling of higher-order Trotter bounds might depend on the order of the Hamiltonians in the Trotter product for states with fat-tailed energy distribution. Physically, the enlarged Trotter error is caused by the atom's ionization due to the Trotter dynamics. Mathematically, we find that certain domain conditions are not satisfied by some states so higher moments of the potential and kinetic energies diverge. Our analytical error analysis agrees with numerical simulations, indicating that we can estimate the state-dependent Trotter error scaling genuinely.
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spelling doaj-art-f3f78c4c63d5403ca9d98e15973668b82024-11-18T15:01:56ZengAmerican Physical SocietyPhysical Review Research2643-15642024-11-016404315510.1103/PhysRevResearch.6.043155Strong error bounds for Trotter and strang-splittings and their implications for quantum chemistryDaniel BurgarthPaolo FacchiAlexander HahnMattias JohnssonKazuya YuasaEfficient error estimates for the Trotter product formula are central in quantum computing, mathematical physics, and numerical simulations. However, the Trotter error's dependency on the input state and its application to unbounded operators remains unclear. Here, we present a general theory for error estimation, including higher-order product formulas, with explicit input state dependency. Our approach overcomes two limitations of the existing operator-norm estimates in the literature. First, previous bounds are too pessimistic as they quantify the worst-case scenario. Second, previous bounds become trivial for unbounded operators and cannot be applied to a wide class of Trotter scenarios, including atomic and molecular Hamiltonians. Our method enables analytical treatment of Trotter errors in chemistry simulations, illustrated through a case study on the hydrogen atom. Our findings reveal the following: (i) for states with fat-tailed energy distribution, such as low-angular-momentum states of the hydrogen atom, the Trotter error scales worse than expected (sublinearly) in the number of Trotter steps; (ii) certain states do not admit an advantage in the scaling from higher-order Trotterization and, thus, the higher-order Trotter hierarchy breaks down for these states, including the hydrogen atom's ground state; (iii) the scaling of higher-order Trotter bounds might depend on the order of the Hamiltonians in the Trotter product for states with fat-tailed energy distribution. Physically, the enlarged Trotter error is caused by the atom's ionization due to the Trotter dynamics. Mathematically, we find that certain domain conditions are not satisfied by some states so higher moments of the potential and kinetic energies diverge. Our analytical error analysis agrees with numerical simulations, indicating that we can estimate the state-dependent Trotter error scaling genuinely.http://doi.org/10.1103/PhysRevResearch.6.043155
spellingShingle Daniel Burgarth
Paolo Facchi
Alexander Hahn
Mattias Johnsson
Kazuya Yuasa
Strong error bounds for Trotter and strang-splittings and their implications for quantum chemistry
Physical Review Research
title Strong error bounds for Trotter and strang-splittings and their implications for quantum chemistry
title_full Strong error bounds for Trotter and strang-splittings and their implications for quantum chemistry
title_fullStr Strong error bounds for Trotter and strang-splittings and their implications for quantum chemistry
title_full_unstemmed Strong error bounds for Trotter and strang-splittings and their implications for quantum chemistry
title_short Strong error bounds for Trotter and strang-splittings and their implications for quantum chemistry
title_sort strong error bounds for trotter and strang splittings and their implications for quantum chemistry
url http://doi.org/10.1103/PhysRevResearch.6.043155
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AT alexanderhahn strongerrorboundsfortrotterandstrangsplittingsandtheirimplicationsforquantumchemistry
AT mattiasjohnsson strongerrorboundsfortrotterandstrangsplittingsandtheirimplicationsforquantumchemistry
AT kazuyayuasa strongerrorboundsfortrotterandstrangsplittingsandtheirimplicationsforquantumchemistry