Dispersive optical systems for scalable Raman driving of hyperfine qubits

TL;DR

This paper presents a passive, high-efficiency method using a chirped Bragg grating for amplitude modulation of lasers to drive hyperfine qubits, enabling scalable, high-fidelity quantum operations in atomic systems.

Contribution

It introduces a novel phase modulation technique with a dispersive optical element for scalable Raman driving of hyperfine qubits, improving stability and efficiency.

Findings

Achieved 2 MHz Rabi frequencies in 300 neutral atom qubits.

Photon-scattering error rates below 2 x 10^{-4} per π-pulse.

Demonstrated compatibility with high-power laser sources.

Abstract

Hyperfine atomic states are among the most promising candidates for qubit encoding in quantum information processing. In atomic systems, hyperfine transitions are typically driven through a two-photon Raman process by a laser field which is amplitude modulated at the hyperfine qubit frequency. Here, we introduce a new method for generating amplitude modulation by phase modulating a laser and reflecting it from a highly dispersive optical element known as a chirped Bragg grating (CBG). This approach is passively stable, offers high efficiency, and is compatible with high-power laser sources, enabling large Rabi frequencies and improved quantum coherence. We benchmark this new approach by globally driving an array of $\sim 300$ neutral $^{87}$Rb atomic qubits trapped in optical tweezers, and obtain Rabi frequencies of 2 MHz with photon-scattering error rates of $< 2 \times 10^{-4}$ per $\pi$-pulse. This robust approach can be directly integrated with local addressing optics in both neutral atom and trapped ion systems to facilitate high-fidelity single-qubit operations for quantum information processing.