@article{13366,
  keywords = {Multidisciplinary},
  author = {Ross Hutson and William Milner and Lingfeng Yan and Jun Ye and Christian Sanner},
  title = {Observation of millihertz-level cooperative Lamb shifts in an optical atomic clock},
  abstract = {<jats:p>Collective couplings of atomic dipoles to a shared electromagnetic environment produce a wide range of many-body phenomena. We report on the direct observation of resonant electric dipole-dipole interactions in a cubic array of atoms in the many-excitation limit. The interactions produce spatially dependent cooperative Lamb shifts when spectroscopically interrogating the millihertz-wide optical clock transition in strontium-87. We show that the ensemble-averaged shifts can be suppressed below the level of evaluated systematic uncertainties for optical atomic clocks. Additionally, we demonstrate that excitation of the atomic dipoles near a Bragg angle can enhance these effects by nearly an order of magnitude compared with nonresonant geometries. Our work demonstrates a platform for precise studies of the quantum many-body physics of spins with long-range interactions mediated by propagating photons.</jats:p>},
  year = {2024},
  journal = {Science},
  volume = {383},
  pages = {384-387},
  month = {2024-01},
  publisher = {American Association for the Advancement of Science (AAAS)},
  issn = {0036-8075, 1095-9203},
  doi = {10.1126/science.adh4477},
}