Toward the real-time evolution of gauge-invariant Z2 and U(1) quantum link models on noisy intermediate-scale quantum hardware with error mitigation

Practical quantum computing holds clear promise in addressing problems not generally tractable with classical simulation techniques, and some key physically interesting applications are those of real-time dynamics in strongly coupled lattice gauge theories. In this article, we benchmark the real-time dynamics of Z2 and U(1) gauge-invariant plaquette models using noisy intermediate-scale quantum (NISQ) hardware, specifically the superconducting-qubit-based quantum IBM Q computers. We design quantum circuits for models of increasing complexity and measure physical observables such as the return probability to the initial state and locally conserved charges. NISQ hardware suffers from significant decoherence and a corresponding difficulty to interpret the results. We demonstrate the use of hardware-agnostic error mitigation techniques, such as circuit folding methods implemented via the Mitiq package, and we show what they can achieve within the quantum volume restrictions for the hardware. Our study provides insight into the choice of Hamiltonians, the construction of circuits, and the utility of error mitigation methods to devise large-scale quantum computation strategies for lattice gauge theories.