TY  - JOUR
AU  - Angelides, Takis
AU  - Naredi, Pranay
AU  - Crippa, Arianna
AU  - Jansen, Karl
AU  - Kühn, Stefan
AU  - Tavernelli, Ivano
AU  - Wang, Derek S.
TI  - First-Order Phase Transition of the Schwinger Model with a Quantum Computer
JO  - npj Quantum information
VL  - 11
IS  - arXiv:2312.12831
SN  - 2056-6387
CY  - London
PB  - Nature Publ. Group
M1  - PUBDB-2025-00211
M1  - arXiv:2312.12831
SP  - 6
PY  - 2025
N1  - 21 pages, 10 figures, 1 table
AB  - We explore the first-order phase transition in the lattice Schwinger model in the presence of a topological θ-term by means of the variational quantum eigensolver (VQE). Using two different fermion discretizations, Wilson and staggered fermions, we develop parametric ansatz circuits suitable for both discretizations, and compare their performance by simulating classically an ideal VQE optimization in the absence of noise. The states obtained by the classical simulation are then prepared on the IBM's superconducting quantum hardware. Applying state-of-the art error-mitigation methods, we show that the electric field density and particle number, observables which reveal the phase structure of the model, can be reliably obtained from the quantum hardware. To investigate the minimum system sizes required for a continuum extrapolation, we study the continuum limit using matrix product states, and compare our results to continuum mass perturbation theory. We demonstrate that taking the additive mass renormalization into account is vital for enhancing the precision that can be obtained with smaller system sizes. Furthermore, for the observables we investigate we observe universality, and both fermion discretizations produce the same continuum limit.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:001397992900002
DO  - DOI:10.1038/s41534-024-00950-6
UR  - https://bib-pubdb1.desy.de/record/622159
ER  -