Gate construction of block-encoding for Hamiltonians needed for simulating partial differential equations

One of the most promising applications of quantum computers is solving partial differential equations (PDEs). By using the Schrödingerization technique—which converts nonconservative PDEs into Schrödinger equations—the problem can be reduced to Hamiltonian simulations. The particular class of Hamilt...

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Main Authors: Nikita Guseynov, Xiajie Huang, Nana Liu
Format: Article
Language:English
Published: American Physical Society 2025-07-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/xlpd-fb1g
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author Nikita Guseynov
Xiajie Huang
Nana Liu
author_facet Nikita Guseynov
Xiajie Huang
Nana Liu
author_sort Nikita Guseynov
collection DOAJ
description One of the most promising applications of quantum computers is solving partial differential equations (PDEs). By using the Schrödingerization technique—which converts nonconservative PDEs into Schrödinger equations—the problem can be reduced to Hamiltonian simulations. The particular class of Hamiltonians we consider is shown to be sufficient for simulating almost any linear PDE. In particular, these Hamiltonians consist of discretizations of polynomial products and sums of position and momentum operators. This paper addresses an important gap by efficiently loading these Hamiltonians into the quantum computer through block-encoding. The construction is explicit and efficient in terms of one- and two-qubit operations, forming a fundamental building block for constructing the unitary evolution operator for that class of Hamiltonians. The proposed algorithm demonstrates a squared logarithmic scaling with respect to the spatial partitioning size, offering a polynomial speedup over classical finite-difference methods in the context of spatial partitioning for solving PDEs. Furthermore, the algorithm is extended to the multidimensional case, achieving an exponential acceleration with respect to the number of dimensions, alleviating the curse of dimensionality problem. This work provides an essential foundation for developing explicit and efficient quantum circuits for PDEs, Hamiltonian simulations, and ground state and thermal state preparation.
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spelling doaj-art-d7eaf535375d4487bc44e29c81fba2f22025-08-20T03:31:33ZengAmerican Physical SocietyPhysical Review Research2643-15642025-07-017303310010.1103/xlpd-fb1gGate construction of block-encoding for Hamiltonians needed for simulating partial differential equationsNikita GuseynovXiajie HuangNana LiuOne of the most promising applications of quantum computers is solving partial differential equations (PDEs). By using the Schrödingerization technique—which converts nonconservative PDEs into Schrödinger equations—the problem can be reduced to Hamiltonian simulations. The particular class of Hamiltonians we consider is shown to be sufficient for simulating almost any linear PDE. In particular, these Hamiltonians consist of discretizations of polynomial products and sums of position and momentum operators. This paper addresses an important gap by efficiently loading these Hamiltonians into the quantum computer through block-encoding. The construction is explicit and efficient in terms of one- and two-qubit operations, forming a fundamental building block for constructing the unitary evolution operator for that class of Hamiltonians. The proposed algorithm demonstrates a squared logarithmic scaling with respect to the spatial partitioning size, offering a polynomial speedup over classical finite-difference methods in the context of spatial partitioning for solving PDEs. Furthermore, the algorithm is extended to the multidimensional case, achieving an exponential acceleration with respect to the number of dimensions, alleviating the curse of dimensionality problem. This work provides an essential foundation for developing explicit and efficient quantum circuits for PDEs, Hamiltonian simulations, and ground state and thermal state preparation.http://doi.org/10.1103/xlpd-fb1g
spellingShingle Nikita Guseynov
Xiajie Huang
Nana Liu
Gate construction of block-encoding for Hamiltonians needed for simulating partial differential equations
Physical Review Research
title Gate construction of block-encoding for Hamiltonians needed for simulating partial differential equations
title_full Gate construction of block-encoding for Hamiltonians needed for simulating partial differential equations
title_fullStr Gate construction of block-encoding for Hamiltonians needed for simulating partial differential equations
title_full_unstemmed Gate construction of block-encoding for Hamiltonians needed for simulating partial differential equations
title_short Gate construction of block-encoding for Hamiltonians needed for simulating partial differential equations
title_sort gate construction of block encoding for hamiltonians needed for simulating partial differential equations
url http://doi.org/10.1103/xlpd-fb1g
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AT xiajiehuang gateconstructionofblockencodingforhamiltoniansneededforsimulatingpartialdifferentialequations
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