Naomy Duarte Gomes1, Barbara da Fonseca Magnani1, Jorge Douglas Massayuki Kondo2, Luis Gustavo Marcassa1
1 Instituto de Fısica de Sao Carlos, Universidade de Sao Paulo
2 Departamento de Fısica, Universidade Federal de Santa Catarina
In this work, we investigate the narrowing of the electromagnetically induced transparency (EIT) profile in a three-level ladder of rubidium atoms at room temperature using a Rydberg state and a Laguerre-Gaussian mode laser. The Gaussian probe field couples the 5S1/2 → 5P3/2 states. The control field, which can be in either Gaussian or Laguerre-Gaussian (LG) modes, couples the 5P3/2 → 44D state. The EIT spectrum is measured with the polarization spectroscopy (PS) technique, resulting in a dispersive signal. The dispersive PS EIT linewidth is 20% narrower for the LG mode than for a Gaussian mode, due to the donut spatial distribution of the LG mode used. We have implemented a probe transmission model using a simplified Lindblad master equation, which allows us to calculate the PS signal and reproduces well the experimental results. The use of the PS signal eliminates the need to fit a curve when measuring EIT linewidths while still providing subnatural widths. Narrowing the transmission profile is of great interest to measure effects such as atomic collisions and mi-crowave fields.
*This work is supported by grants 2016/21311-2, 2019/10971-0 and 2021/06371-7, Sao Paulo Research Foundation (FAPESP) and grant 142410/2019-5, Brazilian National Council for Scientific and Technological Development (CNPq). It is also supported by grant (W911NF2110211) from the US Army.