Improving Single Excitation Fidelity in Rydberg Superatoms for Efficient Single Photon Emission

TL;DR

This paper introduces a pulse shaping technique adapted from superconducting qubits to improve the fidelity of single excitations in Rydberg superatoms, significantly enhancing single photon emission quality.

Contribution

It adapts the DRAG pulse shaping method to atomic systems, achieving higher single excitation probabilities and demonstrating near-optimal control for photon sources.

Findings

Single excitation probability improved from 77% to 91.9%.

DRAG pulses outperform conventional sine-squared pulses.

Approaches fundamental decoherence limits in the system.

Abstract

Deterministic single photon emission from a Rydberg ensemble coupled to an optical cavity requires high-fidelity preparation of collective single excitations. In such a setup imperfect Rydberg blockade can lead to unwanted double excitations, which degrade photon indistinguishability. In this work we adapt the Derivative Removal by Adiabatic Gate (DRAG) technique, originally developed for superconducting qubits, to shape optical pulses that suppress double excitations in this atomic platform. By combining analytical modeling with numerical optimization, DRAG provides an improvement over conventional sine-squared pulses. Further optimization of pulse duration and atomic ensemble size identifies a parameter regime, distinct from that used in [Nature Photonics 17, 688 (2023)], that enhances the single excitation probability from the previous theoretical benchmark of 77% to 91.9%, approaching the fundamental limits set by decoherence in the system. Benchmarking against GRAPE (Gradient Ascent Pulse Engineering) confirms that DRAG operates close to the optimal control limit, while maintaining smooth, experimentally feasible pulse shapes. These results demonstrate the effectiveness and cross platform adaptability of DRAG for a high-fidelity single photon source.