Error Mitigation in Dynamic Circuits for Hamiltonian Simulation

TL;DR

This paper investigates error mitigation strategies, specifically dynamical decoupling and zero-noise extrapolation, to improve the fidelity of dynamic quantum circuits used in Hamiltonian simulation on real hardware.

Contribution

It systematically evaluates combined error mitigation techniques for dynamic circuits, demonstrating significant fidelity improvements in Hamiltonian simulation tasks.

Findings

Combining DD and ZNE improves ground state energy estimation by at least 60%.

Error reduction of up to 99% observed for time-evolved states in the Ising model.

Effective mitigation of errors from mid-circuit measurements and feed-forward operations.

Abstract

Dynamic quantum circuits integrate mid-circuit measurements and feed-forward operations to enable real-time classical processing and conditional quantum logic. These capabilities are central to key quantum protocols such as quantum error correction, and have recently demonstrated significant potential for reducing quantum resources, including circuit depth and gate count, across a range of applications. However, executing dynamic circuits on real quantum hardware introduces a critical trade-off: while resource requirements decrease, circuit fidelity degrades due to high error rates of mid-circuit measurements, as well as the decoherence errors accumulated during the extended idle periods introduced by both mid-circuit measurements and feed-forward operations. In this paper, we systematically investigate the impact of standard error mitigation techniques on dynamic circuit applications pertaining to Hamiltonian simulation and ground state estimation of physically relevant systems like the Heisenberg model. We explore dynamical decoupling (DD) as a strategy to suppress decoherence and crosstalk errors during idle windows introduced by mid-circuit measurements and feed-forward delays, and also examine error mitigation via zero-noise extrapolation (ZNE). Through experiments conducted on IBM quantum hardware, we benchmark effective combinations of these strategies that maximize the practical benefits of dynamic quantum circuits in these applications. We demonstrate that a combination of DD and ZNE is effective in mitigating the errors introduced during mid-circuit measurements and feed-forward operations, as well as the errors arising from faulty measurements. This approach yields a energy gap improvement of at least 60% in ground state estimation and reduces observed error of time-evolved states by up to 99% for the Ising model and up to 20% for the Heisenberg model.