Control and Entanglement of Individual Rydberg Atoms near a Nanoscale Device.

Coherent control of Rydberg atoms near dielectric surfaces is a major challenge due to the large sensitivity of Rydberg states to electric fields. We demonstrate coherent single-atom operations and two-qubit entanglement as close as 100 µm from a nanophotonic device. Using the individual atom control enabled by optical tweezers to study the spatial and temporal properties of the electric field from the surface, we employ dynamical decoupling techniques to characterize and cancel the electric-field noise with submicrosecond temporal resolution. We further use entanglement-assisted sensing to accurately map magnitude and direction of electric-field gradients on a micrometer scale. Our observations open a path for integration of Rydberg arrays with micro- and nanoscale devices for applications in quantum networking and quantum information science.

Dark-State Enhanced Loading of an Optical Tweezer Array.

Neutral atoms and molecules trapped in optical tweezers have become a prevalent resource for quantum simulation, computation, and metrology. However, the maximum achievable system sizes of such arrays are often limited by the stochastic nature of loading into optical tweezers, with a typical loading probability of only 50%. Here we present a species-agnostic method for dark-state enhanced loading (DSEL) based on real-time feedback, long-lived shelving states, and iterated array reloading. We demonstrate this technique with a 95-tweezer array of ^{88}Sr atoms, achieving a maximum loading probability of 84.02(4)% and a maximum array size of 91 atoms in one dimension. Our protocol is complementary to, and compatible with, existing schemes for enhanced loading based on direct control over light-assisted collisions, and we predict it can enable close-to-unity filling for arrays of atoms or molecules.

Entanglement transport and a nanophotonic interface for atoms in optical tweezers.

The realization of an efficient quantum optical interface for multi-qubit systems is an outstanding challenge in science and engineering. Using two atoms in individually controlled optical tweezers coupled to a nanofabricated photonic crystal cavity, we demonstrate entanglement generation, fast nondestructive readout, and full quantum control of atomic qubits. The entangled state is verified in free space after being transported away from the cavity by encoding the qubits into long-lived states and using dynamical decoupling. Our approach bridges quantum operations at an optical link and in free space with a coherent one-way transport, potentially enabling an integrated optical interface for atomic quantum processors.