The line shape of linear optical Ramsey resonance

D. D. Krylova

Ye. V. Baklanov, B. Dubetsky, Veniamin P. Chebotayev

Jiahua Li, Rong Yu, Ying Wu

Optical Fano resonances are an increasingly important line-shape engineering tool with applications ranging from high-sensitivity sensing and ultrasmall lasers to low-power optical switching or modulating. Here we demonstrate a fully on-chip resonant nanostructure on a photonic crystal molecule platform exhibiting typical double- and Ramsey-Fano resonances, which can be actively controlled by the modification of the blockade transmittance in the waveguide. First, we investigate the transmission spectrum of a coupled double-cavity setting, showing a kind of double-Fano resonance line shape which consists of an asymmetric low-frequency Fano (LF) resonance and a high-frequency Fano (HF) resonance. At the same time, we elucidate the influences of various physical quantities on the generated LF and HF resonances. Second, and more interestingly, we reveal the occurrence of the Ramsey-Fano resonance profile by extending a double-cavity arrangement to a coupled-cavity-array arrangement. This Ramsey-Fano resonance can be attributed to the multiple quantum interference among a variety of light pathways. Finally, as an application, we discuss how to use an asymmetric double-Fano resonance line shape, which features the steep spectral slope, to improve the sensing performance. Our obtained results may stimulate future experimental efforts in controlling the double- and Ramsey-Fano resonance line shapes of this system more accurately.

G. Xu, Daniel J. Heinzen

We carry out state-selective Rabi and Ramsey magnetic-resonance experiments on ground-state ${}^{133}\mathrm{Cs}(\mathrm{F}=4)$ atoms. Novel line shapes are obtained, which exhibit very sharp features with a width much smaller than the inverse duration of the magnetic-resonance pulse. The sensitivity of ordinary magnetic-resonance experiments with total spin $\mathrm{F}\mathrm{}>1/2$ is significantly less than the Heisenberg limit, which can be exactly realized only with maximally correlated spin states. We show that the state-selective resonances yield sensitivity very close to the Heisenberg limit, without any state preparation beyond ordinary optical pumping.

К. А. Баранцев, Е. Н. Попов, A N Litvinov

We report a study of the Ramsey technique for detecting coherent population trapping resonance in a cold rarified ensemble of atoms with the collective effects related to its finite optical thickness taken into account. It is found that with the growth of the optical thickness of the medium the Ramsey comb becomes shifted with its maxima ‘trimmed’. The possibility of producing a region of maximal atomic excitation near the exit from the medium is found.

G. KRAMER