TY  - JOUR
AU  - Bishop, Gino
AU  - Bagrets, Dmitry
AU  - Wilhelm, Frank K.
TI  - Quantum algorithm for Green's-function measurements in the Fermi-Hubbard model
JO  - Physical review / A
VL  - 111
IS  - 6
SN  - 2469-9926
CY  - Woodbury, NY
PB  - Inst.
M1  - FZJ-2025-04031
SP  - 062610
PY  - 2025
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:001509152100004
DO  - DOI:10.1103/PhysRevA.111.062610
UR  - https://juser.fz-juelich.de/record/1046963
ER  -