@article{12377,
  author = {Kevin Gilmore and Matthew Affolter and Robert Lewis-Swan and Diego Barberena and Elena Jordan and Ana Maria Rey and John Bollinger},
  title = {Quantum-enhanced sensing of displacements and electric fields with two-dimensional trapped-ion crystals},
  abstract = {Fully controllable ultracold atomic systems are creating opportunities for quantum sensing, yet demonstrating a quantum advantage in useful applications by harnessing entanglement remains a challenging task. Here, we realize a many-body quantum-enhanced sensor to detect displacements and electric fields using a crystal of ~150 trapped ions. The center-of-mass vibrational mode of the crystal serves as a high-Q mechanical oscillator, and the collective electronic spin serves as the measurement device. By entangling the oscillator and collective spin and controlling the coherent dynamics via a many-body echo, a displacement is mapped into a spin rotation while avoiding quantum back-action and thermal noise. We achieve a sensitivity to displacements of 8.8 ± 0.4 decibels below the standard quantum limit and a sensitivity for measuring electric fields of 240 ± 10 nanovolts per meter in 1 second. Feasible improvements should enable the use of trapped ions in searches for dark matter.},
  year = {2021},
  journal = {Science},
  volume = {373},
  pages = {673-678},
  month = {2021-08},
  url = {https://science.sciencemag.org/content/373/6555/673.abstract},
  doi = {10.1126/science.abi5226},
}