We report on our progress on multi-ion spectroscopy with Yb+ions. We first characterized the spatial homogeneity of the magnetic- and the rf-field. Subsequently, to equalize the immense AC Stark shifts of the individual ions in a Coulomb crystal, we utilize a holographic phase plate to convert the Gaussian beam into a flat-top shape. These efforts enable us to excite an 8-ion crystal (172Yb+) on the highly forbidden electric octupole transition. Using 173Yb+ with reduced AC Stark shift, the same beam profile could support the multi-ion operation of 20 ions. This paves the way for future multi-ion optical clocks.
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
87Rb 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.
Abstract The planar-integrated magneto-optical trap (PIMOT) offers a promising platform for miniaturizing cold atom systems, but its performance and laser-power efficiency are limited by the typically Gaussian profile of the input laser beam. In this work, we present a simplified and cost-effective beam shaping solution to transform the Gaussian input into a flat-top intensity distribution using a compact system of four spherical lenses. The reshaped light field could potentially enhances PIMOT performance by improving the uniformity of the optical radiation pressure and increasing the trap distance from the chip surface. With this approach, we demonstrate a substantial reduction in the optical power required to trap 2.5 × 10 5 87 Rb atoms, down to 30% compared to a standard Gaussian beam input. Our results open the door to more efficient and flexible PIMOT systems for quantum sensing, metrology, and atom-based quantum technology.