Dresden 2026 – scientific programme

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QI: Fachverband Quanteninformation

QI 3: Quantum Simulation

QI 3.7: Talk

Monday, March 9, 2026, 17:00–17:15, BEY/0137

Barren-plateau free variational quantum simulation of Z2 lattice gauge theories — •Fariha Azad¹, Matteo Inajetovic¹, Stefan Kühn², and Anna Pappa¹ — ¹Electrical Engineering and Computer Science Department, Technische Universität Berlin, 10587 Berlin, Germany — ²Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, 15738 Zeuthen, Germany

In this work, we design a variational quantum eigensolver (VQE) suitable for investigating ground states and static string breaking in a Z2 lattice gauge theory (LGT). We consider a two-leg ladder lattice with Kogut-Susskind staggered fermions and verify the results of the VQE simulations using tensor network methods. We find that for varying Hamiltonian parameter regimes and in the presence of external charges, the VQE is able to arrive at the gauge-invariant ground state without explicitly enforcing gauge invariance through penalty terms. Additionally, experiments showing string breaking are performed on the IBM quantum platform. Thus, VQEs are seen to be a promising tool for Z2 LGTs, and could serve as a stepping stone toward studies of other gauge groups. We find that the scaling of gradients with the number of qubits is favorable for avoiding barren plateaus. Furthermore, strategies that avoid barren plateaus arise naturally as features of LGTs, such as choosing the initialization by setting the Gauss law sector and restricting the Hilbert space to the gauge-invariant subspace.

Keywords: Variational quantum eigensolver; Lattice gauge theory