Collectively pumped superradiant laser with coherence scaling beyond the standard quantum limit

Abstract

For more than half a century, the standard quantum limit (SQL) was thought to limit the laser coherence C -- the number of photons emitted from the laser into the beam in one coherence time -- to a scaling Θ(μ²), where μ is the mean number of optical-frequency excitations stored inside the laser. However, recently it has been shown [Baker et al., Nat. Phys. 17, 179 (2021)] that the Heisenberg limit -- an achievable ultimate limit set by quantum mechanics for the task of producing a beam with the standard properties of a laser beam -- is C=Θ(μ⁴), a quadratic enhancement. So far, proposals to demonstrate beyond-SQL scaling of C have been limited to circuit QED, at microwave frequencies (i.e., a maser). Here, we introduce a class of generalized far-above-threshold (FAT) laser models, obtained by replacing the ordinary bosonic lowering operator â by a general lowering operator L̂ in the superoperators appearing in the master equation that governs the FAT laser dynamics. We then show that an optical-frequency superradiant laser in the bad-cavity limit, with feedback-controlled collective pumping, realizes one such model, in which L̂ is identified with the collective superradiant lowering operator Ĵ. This model can surpass the SQL scaling, with the coherence exhibiting a scaling as large as C= Θ(μ^8/3) in the optimal parameter regime. Here, in the bad-cavity limit, μ≈ N/2, where N is the number of superradiant atoms.

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Cite

BibTeX RIS

BibTeX

@misc{somech2026collectively,
  title = {{Collectively pumped superradiant laser with coherence scaling beyond the standard quantum limit}},
  author = {Ori Somech and Howard M. Wiseman},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.05976},
  eprint = {2611.05976},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.05976},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - Collectively pumped superradiant laser with coherence scaling beyond the standard quantum limit
AU  - Ori Somech
AU  - Howard M. Wiseman
PY  - 2026
DA  - 2026/11/04
PB  - arXiv
DO  - 10.48550/arxiv.2611.05976
UR  - https://arxiv.org/abs/2611.05976
AB  - For more than half a century, the standard quantum limit (SQL) was thought to limit the laser coherence C -- the number of photons emitted from the laser into the beam in one coherence time -- to a scaling Θ(μ^2), where μ is the mean number of optical-frequency excitations stored inside the laser. However, recently it has been shown [Baker et al., Nat. Phys. 17, 179 (2021)] that the Heisenberg limit -- an achievable ultimate limit set by quantum mechanics for the task of producing a beam with the standard properties of a laser beam -- is C=Θ(μ^4), a quadratic enhancement. So far, proposals to demonstrate beyond-SQL scaling of C have been limited to circuit QED, at microwave frequencies (i.e., a maser). Here, we introduce a class of generalized far-above-threshold (FAT) laser models, obtained by replacing the ordinary bosonic lowering operator â by a general lowering operator L̂ in the superoperators appearing in the master equation that governs the FAT laser dynamics. We then show that an optical-frequency superradiant laser in the bad-cavity limit, with feedback-controlled collective pumping, realizes one such model, in which L̂ is identified with the collective superradiant lowering operator Ĵ. This model can surpass the SQL scaling, with the coherence exhibiting a scaling as large as C= Θ(μ^8/3) in the optimal parameter regime. Here, in the bad-cavity limit, μ≈ N/2, where N is the number of superradiant atoms.
ER  -

Abstract

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