Coherent Control of Neutral Atom Qubits in a Cryogenic Optical Tweezer Array via Raman Transitions

Abstract

Trapped neutral atoms in tweezer arrays are one of the most promising platforms for large-scale quantum information processing and computing. They can be manipulated and measured with single-atom resolution, and exhibit excellent quantum coherence when qubits are stored in hyperfine states. The dynamic reconfigurability of optical tweezers enables the generation of defect-free arrays and non-local connectivity for entangling operations. Entangling operations can be realized with high fidelity by coupling to Rydberg states with large dipole moments, which provide strong interatomic interactions at micrometer separations. Despite substantial progress in recent years, further improvements in two-qubit gate fidelity are highly desirable to reduce the resources needed for fault-tolerant quantum computing. Gate fidelity is fundamentally limited by finite Rydberg T1 lifetimes, typically a hundred microseconds at room temperature, in a large part due to transitions to nearby Rydberg states induced by blackbody radiation (BBR). To address this, we integrate a Cs Rydberg tweezer array into a 4 K cryogenic environment, where suppressed BBR extends the Rydberg lifetime by a factor of 3.3(3) compared to room temperature values. We also encode qubits in the long-lived hyperfine ground-state manifolds, separated by a 9.2 GHz splitting. We report on the construction of a Raman laser system for driving transitions between the hyperfine clock states of cesium, which will allow local qubit control at high Rabi frequencies. The Raman drive is realized using light amplitude-modulated at the hyperfine splitting frequency generated via a chirped Bragg grating, which provides high-efficiency phase-to-amplitude conversion. Integrating this Raman control with the cryogenic Rydberg platform paves the path towards advancing neutral-atom gate fidelities for the realization of large-scale fault-tolerant quantum computers.