A. Crippa - Running coupling of QED 2 + 1 with quantum computing

Monday 3 Apr 2023, 16:15 → 17:30 Europe/Berlin

HISKP

Simone Romiti (uni-bonn)

We propose to utilize NISQ-era quantum devices to compute short distance quantities in (2 + 1)-dimensional QED and to combine them with large volume Monte Carlo simulations and perturbation theory. Since the theory is asymptotically free and confining, it serves as a benchmark model for future studies of Lattice Quantum Chromodynamics in (3 + 1)-dimensions on quantum computers. Employing a Hamiltonian approach on the lattice, we compute observables, e.g. the energy, with a Variational Quantum approach suitable also for excited energy levels, obtaining thus the mass gap of the theory.

We explore methods for the efficient encoding of the system for a quantum circuit and for the minimization procedure.

In the latter case we test various techniques to combine operators and circuits, and test also the performances of the optimizers available (in IBM’s software library Qiskit). In particular, we perform a calculation of the mass gap in the small and intermediate coupling regime, demonstrating, in the latter case, that it can be resolved reliably. The so obtained mass gap can be employed to match corresponding results from Monte Carlo simulations, which can be used eventually to find the value of the lattice spacing and hence to set the physical scale.