S P Ram
Articles written in Pramana – Journal of Physics
Volume 65 Issue 3 September 2005 pp 403-411
Laser frequency stabilization and large detuning by Doppler-free dichroic lock technique: Application to atom cooling
V B Tiwari S R Mishra H S Rawat S Singh S P Ram S C Mehendale
We present results of a study of frequency stabilization of a diode laser (λ = 780 nm) using the Doppler-free dichroic lock (DFDL) technique and its use for laser cooling of atoms. Quantitative measurements of frequency stability were performed and the Allan variance was found to be 6.9 × 1011 for an averaging time of 10 s. The frequency-stabilized diode laser was used to obtain the trapping beams for a magneto-optic trap (MOT) for Rb atoms. Using the DFDL technique, the laser frequency could be locked over a wide range and this enabled measurement of detuning dependence of the number and temperature of cold atoms using a relatively simple experimental set-up.
Volume 68 Issue 6 June 2007 pp 913-924 Research Articles
Collective modes of a quasi-two-dimensional Bose condensate in large gas parameter regime
S R Mishra S P Ram Arup Banerjee
We have theoretically studied the collective modes of a quasi-two-dimensional (Q2D) Bose condensate in the large gas parameter regime by using a formalism which treats the interaction energy beyond the mean-field approximation. The results show that incorporation of this higher order term leads to significant modifications in the mode frequencies.
Volume 82 Issue 2 February 2014 pp 419-423 Contributed Papers
Optimization of transfer of laser-cooled atom cloud to a quadrupole magnetic
S P Ram S K Tiwari S R Mishra H S Rawat
We present here our experimental results on transfer of laser-cooled atom cloud to a quadrupole magnetic trap. We show that by choosing appropriately the ratio of potential energy in magnetic trap to kinetic energy of cloud in molasses, we can obtain the maximum phase-space density in the magnetic trap. These results guide us to choose the value of current to be switched in the quadrupole coils used for magnetic trapping for a given temperature of the cloud after molasses. This study is also useful to set the initial phase-space density of the cloud before evaporative cooling.
Volume 97, 2023
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