Robust M{\o}lmer-S{\o}rensen gate for neutral atoms using rapid adiabatic Rydberg dressing

TL;DR

This paper introduces a robust two-qubit entangling gate for neutral atoms using adiabatic Rydberg dressing, achieving high fidelity by mitigating common experimental errors.

Contribution

It presents a novel adiabatic rapid passage method for implementing a Mølmer-Sørensen gate that is resilient to typical imperfections in neutral atom systems.

Findings

Achieves a gate fidelity of approximately 0.995.

Errors are mainly due to single atom light shifts, correctable with spin echo.

Potential for higher fidelities with improved Rydberg states.

Abstract

The Rydberg blockade mechanism is now routinely considered for entangling qubits encoded in clock states of neutral atoms. Challenges towards implementing entangling gates with high fidelity include errors due to thermal motion of atoms, laser amplitude inhomogeneities, and imperfect Rydberg blockade. We show that adiabatic rapid passage by Rydberg dressing provides a mechanism for implementing two-qubit entangling gates by accumulating phases that are robust to these imperfections. We find that the typical error in implementing a two-qubit gate, such as the controlled phase gate, is dominated by errors in the single atom light shift, and that this can be easily corrected using adiabatic dressing interleaved with a simple spin echo sequence. This results in a two-qubit M{\o}lmer-S{\o}renson gate. A gate fidelity $\sim 0.995$ is achieveable with modest experimental parameters and a path to higher fidelities is possible for Rydberg states in atoms with a stronger blockade, longer lifetimes, and larger Rabi frequencies.