@article{11672,
  author = {Elena Jordan and Kevin Gilmore and Athreya Shankar and Arghavan Safavi-Naini and Justin Bohnet and Murray Holland and John Bollinger},
  title = {Near Ground-State Cooling of Two-Dimensional Trapped-Ion Crystals with More than 100 Ions},
  abstract = {We experimentally study electromagnetically induced transparency cooling of the drumhead modes of planar two-dimensional arrays with up to 
N≈190 Be+ ions stored in a Penning trap. Substantial sub-Doppler cooling is observed for all N drumhead modes. Quantitative measurements for the center-of-mass mode show near ground-state cooling with motional quantum numbers of ¯n=0.3±0.2 obtained within 200 μs. The measured cooling rate is faster than that predicted by single particle theory, consistent with a quantum many-body calculation. For the lower frequency drumhead modes, quantitative temperature measurements are limited by frequency instabilities, but near ground-state cooling of the full bandwidth is strongly suggested. This advance will greatly improve the performance of large trapped ion crystals in quantum information and metrology applications.},
  year = {2019},
  journal = {Physical Review Letters},
  volume = {122},
  pages = {053603},
  month = {2019-02},
  issn = {0031-9007},
  url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.053603},
  doi = {10.1103/PhysRevLett.122.053603},
}