Decoupling of the STIRAP and Microwave-Dressing paths in Trapped Rydberg Ion Gates

TL;DR

This paper proposes a novel pulse sequence for Rydberg ion gates that separates STIRAP and microwave dressing stages, enhancing fidelity and speed for entanglement operations.

Contribution

It introduces a new pulse ordering that prevents interference between STIRAP and microwave dressing, achieving higher fidelity and faster gate operation.

Findings

Achieves a gate fidelity of 99.93% with feasible parameters.

Demonstrates a non-adiabatic gate speed of 400 ns.

Controls entangling phase via asymmetric microwave chirping.

Abstract

The strong dipole-dipole interaction of trapped Rydberg ions offers the possibility of sub-microsecond entanglement gates. For example a two-qubit Control-Phase gate in 88 Sr + ions can be realized, by simultaneous excitation to the Rydberg states via stimulated Raman adiabatic passage (STIRAP) with simultaneous microwave induced dipole-dipole interaction. We show that this excitation protocol distorts the dark-state of the STIRAP stage and is prone to decay from the intermediate state. Here, we propose a novel pulse ordering, in which the STIRAP and the microwave dressing of the Rydberg states occurs in separate stages, preventing mutual interference effects that are detrimental to the gate fidelity. We show that, for experimentally feasible parameters, the proposed excitation scheme can achieve a fidelity of 99.93%, surpassing the experimentally demonstrated gate. In addition, we demonstrate a non-adiabatic speed-up to 400 ns by employing asymmetric pulse shapes in the STIRAP stage. The entangling phase is then controlled solely through the interaction strength by nonresonant asymmetric chirping of the microwave field.