arXiv subjects

Thilagaraj R

Publications and source records attributed to Thilagaraj R.

3 recordsLinked to original sources

arXiv2024

Role of spontaneously generated coherence (SGC) in laser cooling of atoms

The well-known sub-Doppler polarization gradient cooling in type-I transition ($F_e=F_g+1$) is caused by red-detuned lasers. On the other hand, in type-II transition ($F_e\le F_g$), sub-Doppler cooling takes place through blue-detuned lasers. This opposite behavior for the two types of transitions is due to SGC. In the absence of SGC, both types of transitions show blue-detuned cooling. In this work, we experimentally and theoretically demonstrate blue-detuned cooling for both types of transitions in $^{\textrm{87}}$Rb. For completeness, we compare the temperatures in various configurations.

physics.atom-ph↗

arXiv2024

Direct spectroscopy of Rubidium using a narrow-line transition at 420 nm

The 5S$\to$6P transition in Rubidium (Rb) at 420 nm offers the advantage of a narrower linewidth and diverse applications in quantum technologies. However, the direct spectroscopy at this transition is challenging due to its weak transition strength. In this paper, we have discussed the saturated absorption spectroscopy (SAS) of Rb using the narrow-line transition at 420 nm. We have studied the effect of the temperature of the Rb cell, pump power and the beam size on the SAS dip heights and their linewidths. Additionally, our study offers a comprehensive examination, encompassing all eight error signals of Rb for the 5S$\to$6P transition at 420 nm and 421 nm. These findings contribute valuable insights to the field of laser frequency stabilization of Rb at blue transition and can be useful in quantum technologies based on this transition.

physics.atom-ph↗

arXiv2024

Continuous loading of magneto-optical trap of Rb at narrow transition

We report continuous loading of $^{\textrm{87}}$Rb atoms in a magneto-optical trap (MOT) at narrow linewidth, 420 nm 5S$_{1/2}$, F$=2\rightarrow$ 6P$_{3/2}$, F$=3$ blue transition (blue MOT). Continuous loading of the blue MOT is achieved by superimposing the blue laser beam, inside a hollow core of infrared laser beam driving the broad 5S$_{1/2}$, F$=2\rightarrow$ 5P$_{3/2}$, F$=3$ transition at 780 nm. We typically load $\sim10^{8}$ atoms in the blue MOT in 2.5 seconds. We characterize the continuous loading of blue MOT with various parameters such as magnetic field gradient, detuning, power and diameter of blue MOT beam and diameter of the hollow core (spot) inside the IR MOT beam. We observe that the blue laser beam should overfill the spot of the IR laser beam. This is because the blue laser cools the atoms to a lower temperature even in the presence of the broad IR laser i.e. in the overlapped region and hence helps in loading. We also present the theoretical framework for cooling atoms in the presence of simultaneously two transitions to support the experimental result. This method of continuous loading of the blue MOT can be useful to produce a continuous atomic beam of cold Rb atoms.

physics.atom-ph↗