October 31, 2023 to November 4, 2023
Europe/Athens timezone

Exploring Phase structure of the Schwinger model on superconducting Quantum Computers

Not scheduled


Mr Pranay Naredi (The Cyprus Institute)


We explore the phase structure of the lattice Schwinger model in the presence of a toplogical $\theta$-term, a regime in which conventional Monte Carlo simulations suffer from the sign problem, using the variational quantum eigensolver (VQE). Constructing a suitable variational ansatz circuit for the lattice model using symmetry-preserving 2-qubit gates, we perform classical simulations showing that the ansatz is able to capture the relevant physics. In particular, we observe the remnants of the well known first-order phase transition at $\theta=\pi$ occurring in the continuum model for large enough fermion masses. Furthermore, we implement our ansatz on IBM’s superconducting quantum hardware. Using state-of-the art noise suppression techniques, namely readout error mitigation, dynamical decoupling, Pauli twirling, and zero-noise extrapolation, we are able to explore the phase structure of the model directly on quantum hardware with up to 12 qubits. We study two regimes on the hardware device, a fermion mass well below the transition point and a fermion mass well above. In both cases, our ansatz performs well and we obtain data, which are in good agreement with exact diagonalization.

Primary authors

Mr Takis Angelides (DESY Zeuthen, Institut für Physik Humboldt-Universität zu Berlin) Ms Arianna Crippa (DESY Zeuthen, Institut für Physik Humboldt-Universität zu Berlin) Prof. Karl Jansen (DESY Zeuthen, The Cyprus Institute) Dr Stefan Kühn (DESY Zeuthen) Mr Pranay Naredi (The Cyprus Institute) Prof. Ivano Tavernelli (IBM Quantum, IBM Research – Zurich) Dr Derek S. Wang (IBM Quantum, IBM T. J. Watson Research Center)

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