No Tradeoff between Coherence and Sub-Poissonianity for Heisenberg-Limited Lasers

The Heisenberg limit to laser coherence C—the number of photons in the maximally populated mode of the laser beam—is the fourth power of the number of excitations inside the laser. We generalize the previous proof of this upper bound scaling by dropping the requirement that the beam photon statistics be Poissonian (i.e., Mandel’s Q=0). We then show that the relation between C and sub-Poissonianity (Q<0) is win-win, not a tradeoff. For both regular (non-Markovian) pumping with semiunitary gain (which allows Q1), and random (Markovian) pumping with optimized gain, C is maximized when Q is minimized.

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  • Received 6 September 2022
  • Accepted 27 March 2023

DOI:https://doi.org/10.1103/PhysRevLett.130.183602

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General PhysicsAtomic, Molecular & Optical

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