A scheme for the generation of nonclassical pairs of photons in atomic vapors is proposed. The scheme exploits the fact that the cross correlation of the emission of photons from the extreme transitions of a four-level cascade system shows antibunching, unlike the case of the three-level cascade emission, which shows bunching. The Cauchy-Schwarz inequality, which is the ratio of the cross-correlation to the autocorrelation function, in this case is estimated to be ${10}^{3}--{10}^{6}$ for controllable time delay, and is one to four orders of magnitude larger compared to previous experiments. The choice of Doppler-free geometry, in addition to the fact that at three-photon resonance the excitation and deexcitation processes occur in a very narrow frequency band, ensures cleaner signals.A scheme for the generation of nonclassical pairs of photons in atomic vapors is proposed. The scheme exploits the fact that the cross correlation of the emission of photons from the extreme transitions of a four-level cascade system shows antibunching, unlike the case of the three-level cascade emission, which shows bunching. The Cauchy-Schwarz inequality, which is the ratio of the cross-correlation to the autocorrelation function, in this case is estimated to be ${10}^{3}--{10}^{6}$ for controllable time delay, and is one to four orders of magnitude larger compared to previous experiments. The choice of Doppler-free geometry, in addition to the fact that at three-photon resonance the excitation and deexcitation processes occur in a very narrow frequency band, ensures cleaner signals.

arXiv:0707.0720Physical Review AJul 3, 20071 citation

Observation of a three-photon electromagnetically induced transparency in hot atomic vapor

Alexander S. Zibrov, C. Y. Ye, Yuri V. Rostovtsev +2 more

We demonstrate experimentally the effect of a three-photon electromagnetically induced transparency in hot ${}^{85}\mathrm{Rb}$ atomic vapor driven by two coherent electromagnetic fields. The narrow transparency window is observed on the background of high-contrast Doppler-free subnatural absorption resonance. Our analytical calculations and numerical simulations are in good agreement with the experimental data. Both the transparency and the absorption resonances can find applications in high-precision metrology.We demonstrate experimentally the effect of a three-photon electromagnetically induced transparency in hot ${}^{85}\mathrm{Rb}$ atomic vapor driven by two coherent electromagnetic fields. The narrow transparency window is observed on the background of high-contrast Doppler-free subnatural absorption resonance. Our analytical calculations and numerical simulations are in good agreement with the experimental data. Both the transparency and the absorption resonances can find applications in high-precision metrology.

Physical Review AApr 4, 200278 citations

Toward lasing without inversion in the ultraviolet regime: Doppler-free three-photon coherence effects in mercury vapor

Benjamin Rein, Jochen M. Schmitt, Martin R. Sturm +2 more

Doppler-free three-photon coherence effects at a wavelength of $253.7\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$ were observed in thermal mercury vapor. The experimental results are compared to simulations based on a detailed theoretical model reproducing the measured effects. Based on these results, we show by simulations that amplification without inversion in our setup is feasible, paving the way towards lasing without inversion in mercury.Doppler-free three-photon coherence effects at a wavelength of $253.7\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$ were observed in thermal mercury vapor. The experimental results are compared to simulations based on a detailed theoretical model reproducing the measured effects. Based on these results, we show by simulations that amplification without inversion in our setup is feasible, paving the way towards lasing without inversion in mercury.

arXiv:2111.03023Physical Review AFeb 24, 20226 citations

{10}^{3}--{10}^{6}

for controllable time delay, and is one to four orders of magnitude larger compared to previous experiments. The choice of Doppler-free geometry, in addition to the fact that at three-photon resonance the excitation and deexcitation processes occur in a very narrow frequency band, ensures cleaner signals.

We demonstrate experimentally the effect of a three-photon electromagnetically induced transparency in hot

{}^{85}\mathrm{Rb}

atomic vapor driven by two coherent electromagnetic fields. The narrow transparency window is observed on the background of high-contrast Doppler-free subnatural absorption resonance. Our analytical calculations and numerical simulations are in good agreement with the experimental data. Both the transparency and the absorption resonances can find applications in high-precision metrology.

Doppler-free three-photon coherence effects at a wavelength of

253.7\phantom{\rule{0.16em}{0ex}}\mathrm{nm}

were observed in thermal mercury vapor. The experimental results are compared to simulations based on a detailed theoretical model reproducing the measured effects. Based on these results, we show by simulations that amplification without inversion in our setup is feasible, paving the way towards lasing without inversion in mercury.