High-sensitivity measurement of Rydberg population via two-photon excitation in atomic vapour using optical heterodyne detection technique

Pramana: Journal of physics

ARUP BHOWMICK^1¹ 

[1] School of Physical Sciences, National Institute of Science Education and Research Bhubaneswar, HBNI, P.O. Jatni, Khurda 752 050, India^1

关键词: Heterodyne;    Rydberg population;    two-photon;    atomic vapour;    dispersion;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

We demonstrate a technique based on optical heterodyne detection to measure the Rydberg population in the thermal atomic vapour. The technique used a probe beam far off-resonant to the D2 line of rubidium along with a reference beam with frequency offset by 800 MHz in the presence of a coupling laser that couples to Rydberg state via two-photon resonance. The polarisation of the probe, reference and coupling beams are suitably chosen such that only the probe beam goes through a nonlinear phase shift due to the two-photon process which is measured relative to the phase shift of the reference beam using optical heterodyne detection technique. We show that the technique has a sensitivity to measure the minimum phase shift of the order of a few $\mu$rad. We have used a suitable model of two-photon excitation of a three-level atom to show that the minimum phase shift measured in our experiment corresponds to the Rydberg population of the order of $10^{−5}$. The corresponding probe absorption for the given laser parameters is of the order of $10^{−7}$. We demonstrate that this technique is insensitive to polarisation impurity or fluctuations in the beams. The technique is particularly useful in measuring the Rydberg population via two-photon excitation in thermal vapour where microchannel plates (MCP) could be relatively difficult to implement. It can also be used in the ultracold atomic sample with suitable laser parameters.

【 授权许可】

CC BY