Probing beyond the laser coherence time in optical clock comparisons

@article{Hume2015ProbingBT,
  title={Probing beyond the laser coherence time in optical clock comparisons},
  author={David B. Hume and David R. Leibrandt},
  journal={Physical Review A},
  year={2015},
  volume={93},
  pages={032138}
}
We develop differential measurement protocols that circumvent the laser noise limit in the stability of optical clock comparisons by synchronous probing of two clocks using phase-locked local oscillators. This allows for probe times longer than the laser coherence time, avoids the Dick effect, and supports Heisenberg-limited measurement precision. We present protocols for such frequency comparisons and develop numerical simulations of the protocols with realistic noise sources. These methods… 
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