Multiqubit Toffoli gates and optimal geometry with Rydberg atoms

TL;DR

This paper presents a method for implementing high-fidelity multiqubit Toffoli gates using Rydberg atoms arranged in a spheroidal array, optimized via evolutionary algorithms for robustness and low error.

Contribution

It introduces a novel spheroidal atomic array configuration and an optimization method to enhance multiqubit gate fidelity and robustness in neutral-atom quantum computing.

Findings

Achieved a C6NOT gate fidelity of 0.992 with typical experimental parameters.

Demonstrated robustness of the gate to spatial position variations.

Enhanced asymmetric Rydberg blockade through optimized control-qubit distributions.

Abstract

Due to its potential for implementing a scalable quantum computer, multiqubit Toffoli gate lies in the heart of quantum information processing. In this article, we demonstrate a multiqubit blockade gate with atoms arranged in a three-dimension spheroidal array. The gate performance is greatly improved by the method of optimizing control-qubit distributions on the spherical surface via evolutionary algorithm, which leads to an enhanced asymmetric Rydberg blockade. This spheroidal configuration, not only arises a well preservation for the dipole blockade energy between arbitrary control-target pairs, which keeps the asymmetric blockade error at a very low level; but also manifests an unprecedented robustness to the spatial position variations, leading to a negligible position error. Taking account of intrinsic errors and with typical experimental parameters, we numerically show that a C$_6$NOT Rydberg gate can be created with a fidelity of 0.992 which is only limited by the Rydberg state decays.Our protocol opens up a new platform of higher-dimensional atomic arrays for achieving multiqubit neutral-atom quantum computation.