Optimized Geometric Quantum Computation with mesoscopic ensemble of Rydberg Atoms

TL;DR

This paper presents a fast, robust, and high-fidelity quantum computation scheme using mesoscopic Rydberg atoms, combining geometric quantum gates, optimal control, and dispersive coupling to mitigate errors and decoherence.

Contribution

It introduces a novel nonadiabatic geometric quantum computation method with error suppression techniques for Rydberg atom ensembles, enhancing fidelity and robustness.

Findings

Achieves over 99.9% fidelity for single and two-qubit gates in ideal conditions.

Maintains over 99.94% fidelity with 10% Rabi frequency fluctuations.

Reduces errors from higher-order perturbations and decoherence through optimized control and dispersive coupling.

Abstract

We propose a nonadiabatic non-Abelian geometric quantum operation scheme to realize universal quantum computation with mesoscopic Rydberg atoms. A single control atom entangles a mesoscopic ensemble of target atoms through long-range interactions between Rydberg states. We demonstrate theoretically that both the single qubit and two-qubit quantum gates can achieve high fidelities around or above 99.9% in ideal situations. Besides, to address the experimental issue of Rabi frequency fluctuation (Rabi error) in Rydberg atom and ensemble, we apply the dynamical-invariant-based zero systematic-error sensitivity (ZSS) optimal control theory to the proposed scheme. Our numerical simulations show that the average fidelity could be 99.98% for single ensemble qubit gate and 99.94% for two-qubit gate even when the Rabi frequency of the gate laser acquires 10% fluctuations. We also find that the optimized scheme can also reduce errors caused by higher-order perturbation terms in deriving the Hamiltonian of the ensemble atoms. To address the experimental issue of decoherence error between the ground state and Rydberg levels in Rydberg ensemble, we introduce a dispersive coupling regime between Rydberg and ground levels, based on which the Rydberg state is adiabatically discarded. The numerical simulation demonstrate that the quantum gate is enhanced. By combining strong Rydberg atom interactions, nonadiabatic geometric quantum computation, dynamical invariant and optimal control theory together, our scheme shows a new route to construct fast and robust quantum gates with mesoscopic atomic ensembles. Our study contributes to the ongoing effort in developing quantum information processing with Rydberg atoms trapped in optical lattices or tweezer arrays.