Frontiers and Careers in Nuclear and Hadronic Physics 2023

Exploring Phase structure of the Schwinger model on superconducting Quantum Computers

30 Oct 2023, 10:30

20m

Student and Postdoc Talks Research Talks

Speaker

Pranay Naredi (The Cyprus Institute)

Description

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.

Presentation materials

Exploring Phase Structure of the Schwinger Model on Superconducting Quantum Computers.pdf