Extended Single-Atom Tweezer Arrays in High-Cooperativity Cavity-QED

This study addresses a key challenge in quantum technology: combining the local control and site-resolved detection of optical tweezer arrays with the strong, collective light-matter interaction provided by high-cooperativity optical cavities. While previous experiments have achieved strong coupling with single atoms or small groups, scaling this to larger, programmable arrays is essential for advanced quantum simulation and networking. The authors utilize a fiber Fabry-Perot microcavity and a background-free fluorescence imaging scheme to achieve this integration.

The apparatus traps $^{87}$Rb atoms in an optical tweezer array within a fiber Fabry-Perot microcavity. To overcome the significant background noise typically caused by scattering from nearby fiber surfaces, the team implemented a two-photon 'diamond' excitation scheme. This allows for background-free fluorescence imaging, enabling the researchers to resolve individual atoms in arrays of up to 20x4 sites. The atoms are further stabilized using an intracavity lattice that pins them to the antinodes of the probe field, ensuring consistent coupling.

The researchers successfully demonstrated a single-atom cooperativity of $\mathcal{C} \simeq 90$. They validated the system by performing cavity-based hyperfine-state detection with fidelities exceeding 98.8% across the entire spatial extent of a 20x5-site array. By scaling the array size to a mean atom number of $\bar{N} \simeq 36$, they observed collective enhancement of the atom-cavity coupling, confirming that the platform maintains high cooperativity even with extended, multi-row atomic configurations. This setup provides a robust, programmable interface for many-body cavity-QED.

This platform bridges the gap between individual qubit control and collective cavity-mediated interactions. By enabling site-resolved readout and programmable atomic geometries within a high-cooperativity environment, this work provides a scalable foundation for applications such as quantum networks, long-range spin models for quantum simulation, and cavity-mediated gates between quantum processors.