Southwest Quantum Information and Technology

Impact of dynamics, entanglement, and incoherent noise on the fidelity of few-qubit digital quantum simulation

Presenting Author: Max D. Porter, Laurence Livermore National Laboratory
Contributing Author(s): Ilon Joseph

Quantum chaotic simulations stand to be one of the most important application areas for quantum computing. This is due to the need to simulate these systems numerically and the exponential resources needed to simulate them on classical computers. We study the quantum sawtooth map (QSM), a gate- and qubit-efficient system, as a prototypical example of quantum chaotic Hamiltonian simulation. We investigate the interaction of a gate-based Lindblad noise model with localization and diffusion in the QSM. Theoretical expressions for the fidelity decays of each are derived, validated with simulation, and their difference qualitatively observed in experiment. We find the rate of fidelity decay increases continuously from fully localized to fully diffusive dynamics due to both increased dephasing and a partial relaxation caused by random entanglement. From experiment the “effective” T1 and T2 times are extracted by fitting theory and simulations to data from IBM-Q. The effective T2 time is found to be 2.7x worse than reported for single-qubit T2, and the CNOT gate error is up to 4.5x worse than reported for randomized benchmarking. This illustrates the importance of complex dynamics for benchmarking near-term quantum devices. *Work for LLNL-ABS-838050 was prepared for US DOE by LLNL under Contract DE-AC52-07NA27344 and was supported by the DOE Office of Fusion Energy Sciences “Quantum Leap for Fusion Energy Sciences” project AT1030200-SCW1680.

Read this article online: https://doi.org/10.48550/arXiv.2206.04829

(Session 9a : Friday from 4:15 pm - 4:45 pm)