Optical Rotation of Few-Ion Crystals in a Linear Paul Trap

The linear Paul trap provides a widely-used architecture in the field of quantum computing and quantum information processing. However, the rotational motion of ions has not accrued much attention until a recent study by E. Urban et al. [1], where trap voltages were engineered to coherently control a two-ion crystal. Ionic rotors are expected to be a promising candidate for precision measurements, stimulating Hawking radiation, and studying Aharonov-Bohm type physics. Here we explore a variety of few ion-Coulomb crystal conformations by regulating appropriate confinement strengths along the radial and axial directions of a linear radio-frequency trap and investigate their rotation under the influence of an asymmetrically placed Gaussian cooling beam. Specifically, we present a detailed theoretical characterization of the radiation-pressure induced rotation of a two-ion crystal inside the trap. We also present experimental data with which the theoretical calculations agree very well. Our work opens up the investigation of circular, elliptical, planar as well as non-planar ion rotation.

[1]  E. Urban et al., Phys. Rev. Lett. 123, 133202 (2019).