Double dark resonances in a four-level atomic model

Jun Kou, Ren-Gang Wan, Shang-qi Kuang +5 more

Yongfang Li, Jianfeng Sun, Xian-Yang Zhang +1 more

Dongchao Cheng, Chengpu Liu, Yueping Niu +3 more

We propose two schemes of atom localization based on the interference of double-dark resonances in a tripod and a 'Lambda'-type four-level system. It is demonstrated that the localization is significantly improved owing to the interference of double-dark resonances. In the tripod scheme, the localization can be manipulated by the parameters of an additional control field. Via adjusting the Rabi frequency of the field, one can double the probability of detecting the atom within subwavelength domain. By decreasing the detuning of the field, higher spatial resolution can be achieved. In the 'Lambda'-type four-level system, via adjusting the probe field detuning, we can not only make the atom localized at the nodes of the standing-wave field with high precision, but also increase the detecting probability of the atom at a particular position by a factor of 2.

C. Y. Ye, Alexander S. Zibrov, Yuri V. Rostovtsev

Spectroscopy of the Doppler broadened Rb atomic vapour coherently driven by two coupling fields is presented. Double dark resonances have been observed in different geometries of the coupling fields. A simple four-level model explains the basic counter-intuitive features of experimental spectra. The eigenvalues of the atom-field system distinguishing between the various geometries clarify the physics.

Yuri Ozhigov

Zhiping Wang

Recent years have seen vast progress in the generation and detection of vortex light, with potential applications in classical and quantum optics. However, it is still a challenge to efficiently generate high-fidelity vortex wavefronts in practical applications. Here, we propose a scheme to reconstruct the high-fidelity vortex wavefront via double dark resonances in a four-level atomic system. It is shown that, owing to a microwave field which interacts with magnetic or electric dipole moments of relevant atomic transitions, thereby generating spatially varying double dark resonances which in turn lead to the reconstruction of the incident probe field. In addition, to gauge the quality of the reconstructed probe field in comparison to the incident probe field, we study the fidelity of the reconstructed probe field and find that the reconstructed mode has a fidelity of more than 90% under the double-dark resonant condition. This study would be helpful to demonstrate optical vortex manipulation in atomic media.