%0 Journal Article
%A Bishop, Gino
%A Bagrets, Dmitry
%A Wilhelm, Frank K.
%T Quantum algorithm for Green's-function measurements in the Fermi-Hubbard model
%J Physical review / A
%V 111
%N 6
%@ 2469-9926
%C Woodbury, NY
%I Inst.
%M FZJ-2025-04031
%P 062610
%D 2025
%X In the framework of the hybrid quantum-classical variational cluster approach to strongly correlated electron systems one of the goals of a quantum subroutine is to find single-particle correlation functions of lattice fermions in polynomial time. Previous works suggested to use variants of the Hadamard test for this purpose, which requires an implementation of controlled single-particle fermionic operators. However, for a number of locality-preserving mappings to encode fermions into qubits, a direct construction of such operators is not possible. In this work, we propose a quantum algorithm that uses an analog of the Kubo formula adapted to a quantum circuit simulating the Hubbard model. It allows to access the Green's function of a cluster directly using only bilinears of fermionic operators and circumvents the usage of the Hadamard test. We test our algorithm in practice by using open-access simulators of noisy IBM superconducting chips.
%F PUB:(DE-HGF)16
%9 Journal Article
%R 10.1103/PhysRevA.111.062610
%U https://juser.fz-juelich.de/record/1046963