High-fidelity multiqubit Rydberg gates via two-photon adiabatic rapid passage

TL;DR

This paper introduces a robust two-photon adiabatic rapid passage protocol for high-fidelity multiqubit controlled phase gates in neutral atom Rydberg systems, accounting for decay and Stark shifts.

Contribution

The authors develop a new adiabatic passage method for multiqubit gates that improves fidelity and robustness in neutral atom Rydberg quantum computing.

Findings

Achieves >99.5% fidelity for 3-qubit CCZ gate in 1.8 μs.

Attains >99% fidelity for 4-qubit CCCZ gate.

Protocols are compatible with current laser technology.

Abstract

We present a robust protocol for implementing high-fidelity multiqubit controlled phase gates $(C^kZ)$ on neutral atom qubits coupled to highly excited Rydberg states. Our approach is based on extending adiabatic rapid passage to two-photon excitation via a short-lived intermediate excited state common to alkali-atom Rydberg experiments, accounting for the full impact of spontaneous decay and differential AC Stark shifts from the complete manifold of hyperfine excited states. We evaluate and optimize gate performance, concluding that for Cs and currently available laser frequencies and powers, a $CCZ$ gate with fidelity $\mathcal{F}>0.995$ for three qubits and $CCCZ$ with $\mathcal{F}>0.99$ for four qubits is attainable in $\sim 1.8$~$\mu$s via this protocol. Higher fidelities are accessible with future technologies, and our results highlight the ultility of neutral atom arrays for the native implementation of multiqubit unitaries.