Error-budgeting for a controlled-phase gate with strontium-88 Rydberg atoms

TL;DR

This paper presents optimized pulse shapes for a high-fidelity controlled-phase gate in a strontium-88 Rydberg atom quantum computer, reducing gate time and infidelity through tailored laser pulses.

Contribution

It introduces pulse optimization techniques that shorten Rydberg state duration and improve gate fidelity, applicable to realistic experimental conditions.

Findings

Achieved over 99.9% gate fidelity with conservative parameters.

Reduced Rydberg state occupation time by 10%.

Analyzed fundamental error sources impacting fidelity.

Abstract

We study the implementation of a high fidelity controlled-phase gate in a Rydberg quantum computer. The protocol is based on a symmetric gate with respect to the two qubits as experimentally realized by Levine et al [Phys. Rev. Lett. 123, 170503 (2019)], but allows for arbitrary pulse shapes with time-dependent detuning. Optimizing the pulse shapes, we introduce laser pulses which shorten the time spent in the Rydberg state by 10% and reduce the leading contribution to the gate infidelity, i.e., the decay from the Rydberg state. Remarkably, this reduction can be achieved for smooth pulses in detuning and smooth turning on of the Rabi frequency as required in any experimental realization. We carefully analyze the influence of fundamental error sources such as the photon recoil, the microscopic interaction potential, as well as the harmonic trapping of the atoms for an experimentally realistic setup based on strontium-88 atoms. We find that an average gate fidelity above 99.9% is possible for a very conservative estimation of experimental parameters.