Curator's Take
This article tackles a crucial challenge in neutral atom quantum computing: how to precisely control individual atoms in dense arrays without affecting their neighbors. The researchers developed a sophisticated "flat-top" laser beam that maintains uniform intensity across its focal region, enabling clean addressing of target atoms while minimizing crosstalk - a key requirement for scaling up neutral atom quantum computers. Their experimental demonstration showing clear differences in Rabi oscillation visibility between addressed and neighboring atoms proves this approach can achieve the spatial selectivity needed for high-fidelity quantum operations. This beam shaping technique represents an important step toward building larger, more precise neutral atom quantum processors that can compete with other leading quantum computing platforms.
— Mark Eatherly
Summary
We present a method for generating a laser beam with flat intensity and phase profiles in the focal region where the beam interacts with neutral $^{87}$Rb atoms in an array of optical dipole traps. We synthesize the beam as a superposition of Hermite--Gaussian or Laguerre--Gaussian modes. Then we give analytical expressions for the coefficients of such a superposition, an analysis of beam propagation along the $z$ axis in the vicinity of the waist, and several other related theoretical issues. Rydberg two-qubit dynamics driven by this flat-top profile are analyzed through numerical solutions of the Lindblad master equation using our in-house Julia package. Beam preparation is demonstrated on a neutral-atom experimental platform. Measurements reveal a difference in the visibility of Rabi oscillations for addressed atoms compared with neighboring ones, confirming the effective spatial selectivity provided by the flat-top beam profile.