Computation of Green's function by local variational quantum compilation

Computation of the Green's function is crucial to study the properties of quantum many-body systems such as strongly correlated systems. Although the high-precision calculation of the Green's function is a notoriously challenging task on classical computers, the development of quantum comp...

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Main Authors: Shota Kanasugi, Shoichiro Tsutsui, Yuya O. Nakagawa, Kazunori Maruyama, Hirotaka Oshima, Shintaro Sato
Format: Article
Language:English
Published: American Physical Society 2023-08-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.5.033070
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author Shota Kanasugi
Shoichiro Tsutsui
Yuya O. Nakagawa
Kazunori Maruyama
Hirotaka Oshima
Shintaro Sato
author_facet Shota Kanasugi
Shoichiro Tsutsui
Yuya O. Nakagawa
Kazunori Maruyama
Hirotaka Oshima
Shintaro Sato
author_sort Shota Kanasugi
collection DOAJ
description Computation of the Green's function is crucial to study the properties of quantum many-body systems such as strongly correlated systems. Although the high-precision calculation of the Green's function is a notoriously challenging task on classical computers, the development of quantum computers may enable us to compute the Green's function with high accuracy even for classically-intractable large-scale systems. Here, we propose an efficient method to compute the real-time Green's function based on the local variational quantum compilation (LVQC) algorithm, which simulates the time evolution of a large-scale quantum system using a low-depth quantum circuit constructed through optimization on a smaller-size subsystem. Our method requires shallow quantum circuits to calculate the Green's function and can be utilized on both near-term noisy intermediate-scale and long-term fault-tolerant quantum computers depending on the computational resources we have. We perform a numerical simulation of the Green's function for the one- and two-dimensional Fermi-Hubbard model up to 4×4 sites lattice (32 qubits) and demonstrate the validity of our protocol compared to a standard method based on the Trotter decomposition. We finally present a detailed estimation of the gate count for the large-scale Fermi-Hubbard model, which also illustrates the advantage of our method over the Trotter decomposition.
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spelling doaj.art-48b37446daad497a9100ad1334283f032024-04-12T17:32:55ZengAmerican Physical SocietyPhysical Review Research2643-15642023-08-015303307010.1103/PhysRevResearch.5.033070Computation of Green's function by local variational quantum compilationShota KanasugiShoichiro TsutsuiYuya O. NakagawaKazunori MaruyamaHirotaka OshimaShintaro SatoComputation of the Green's function is crucial to study the properties of quantum many-body systems such as strongly correlated systems. Although the high-precision calculation of the Green's function is a notoriously challenging task on classical computers, the development of quantum computers may enable us to compute the Green's function with high accuracy even for classically-intractable large-scale systems. Here, we propose an efficient method to compute the real-time Green's function based on the local variational quantum compilation (LVQC) algorithm, which simulates the time evolution of a large-scale quantum system using a low-depth quantum circuit constructed through optimization on a smaller-size subsystem. Our method requires shallow quantum circuits to calculate the Green's function and can be utilized on both near-term noisy intermediate-scale and long-term fault-tolerant quantum computers depending on the computational resources we have. We perform a numerical simulation of the Green's function for the one- and two-dimensional Fermi-Hubbard model up to 4×4 sites lattice (32 qubits) and demonstrate the validity of our protocol compared to a standard method based on the Trotter decomposition. We finally present a detailed estimation of the gate count for the large-scale Fermi-Hubbard model, which also illustrates the advantage of our method over the Trotter decomposition.http://doi.org/10.1103/PhysRevResearch.5.033070
spellingShingle Shota Kanasugi
Shoichiro Tsutsui
Yuya O. Nakagawa
Kazunori Maruyama
Hirotaka Oshima
Shintaro Sato
Computation of Green's function by local variational quantum compilation
Physical Review Research
title Computation of Green's function by local variational quantum compilation
title_full Computation of Green's function by local variational quantum compilation
title_fullStr Computation of Green's function by local variational quantum compilation
title_full_unstemmed Computation of Green's function by local variational quantum compilation
title_short Computation of Green's function by local variational quantum compilation
title_sort computation of green s function by local variational quantum compilation
url http://doi.org/10.1103/PhysRevResearch.5.033070
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AT hirotakaoshima computationofgreensfunctionbylocalvariationalquantumcompilation
AT shintarosato computationofgreensfunctionbylocalvariationalquantumcompilation