Bright and Tunable Entangled Photon Pairs from Superradiant Emission in a Warm Cs Atomic Ensemble
POSTER
Abstract
Superradiance is a collective radiative phenomenon in which emission from an ensemble of emitters is coherently enhanced beyond the single-particle limit. When atomic ensembles enter the subwavelength regime, cooperative emission can strongly modify both the temporal and spectral properties of generated light, providing new opportunities for engineering quantum light sources.
In this work, we demonstrate superradiance-assisted photon-pair generation in a warm 133Cs atomic ensemble via spontaneous four-wave mixing on the 6S1/2-6P3/2-6D5/2 ladder-type transition. By employing a thin vapor cell and increasing the atomic density through temperature control, the average interatomic distance is reduced to the subwavelength regime, where collective emission becomes pronounced. In this superradiant regime, we observe a narrowing of the temporal cross-correlation of signal and idler photons, accompanied by spectral broadening of the emitted photons. The broadened spectrum suppresses photon reabsorption at high optical depth and enables a substantial enhancement of photon-pair brightness while maintaining strong temporal correlations. We further verify polarization entanglement of the generated photon pairs, demonstrating that the collective emission process preserves quantum correlations even in this regime. Moreover, the superradiance-induced spectral broadening provides a pathway toward tunable photon-pair sources through controlled adjustment of atomic density by the vapor cell temperature.
These results establish superradiance as a versatile physical resource for realizing bright, entangled, and spectrally tunable photon-pair sources in warm atomic vapors, highlighting their potential for practical quantum networking and scalable photonic quantum technologies.
In this work, we demonstrate superradiance-assisted photon-pair generation in a warm 133Cs atomic ensemble via spontaneous four-wave mixing on the 6S1/2-6P3/2-6D5/2 ladder-type transition. By employing a thin vapor cell and increasing the atomic density through temperature control, the average interatomic distance is reduced to the subwavelength regime, where collective emission becomes pronounced. In this superradiant regime, we observe a narrowing of the temporal cross-correlation of signal and idler photons, accompanied by spectral broadening of the emitted photons. The broadened spectrum suppresses photon reabsorption at high optical depth and enables a substantial enhancement of photon-pair brightness while maintaining strong temporal correlations. We further verify polarization entanglement of the generated photon pairs, demonstrating that the collective emission process preserves quantum correlations even in this regime. Moreover, the superradiance-induced spectral broadening provides a pathway toward tunable photon-pair sources through controlled adjustment of atomic density by the vapor cell temperature.
These results establish superradiance as a versatile physical resource for realizing bright, entangled, and spectrally tunable photon-pair sources in warm atomic vapors, highlighting their potential for practical quantum networking and scalable photonic quantum technologies.
Publication: (preprint) Kim, H., Seo, B. & Moon, H. S. Bright heralded single-photon superradiance in a high-density thin vapor cell. arXiv 2601.13909 (2026). https://doi.org/10.48550/arXiv.2601.13909
Presenters
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HeeWoo Kim
- Pusan National University