Bose einstein condensate based atom optics delta kicked rotor for precision measurements

Abstract

This thesis presents the realization of a Bose Einstein Condensate BEC basedAtom Optics delta Kicked Rotor experiment AOKR using 87Rb atoms and its utility inatom interferometry and precision measurements The AOKR involves subjecting theBEC to a series of optical lattice pulses The phase modulation of the BEC wavefunctiondue to the optical lattice potential splits it into discrete momentum states Whenthe pulse period is equal to an integer or half integer multiple of the 8216 Talbot time 8217 thetotal energy imparted to the system per pulse either quadratically increases resonance or is completely suppressed anti resonance Monitoring these resonances allows measurement of Talbot time which is connected to the atomic recoil frequency The recoilfrequency along with other physical quantities constitutes the fine structure constant alpha Since the value of alpha governs the strength of interactions between elementary particles its precision measurement via different techniques is important In the AOKR pulse scheme that we follow the optical lattice pulse phase modulation is negated by inverting its sign for the rest of the pulses The measurement of the revival of the initial stateor the fidelity then constitutes as the Talbot time measurement The sign inversion ofthe phase modulation is brought about by shifting the phase of the optical lattice by pi radians The pulse scheme can also be thought of as a multi path atom interferometer The BEC which is used as an input for this interferometer is obtained after laser coolingin a Magneto Optical Trap MOT and subsequent evaporative cooling in an hybrid opticalcrossed dipole trap Since the quasi momentum dynamics are theoretically predictedto play an important role in the dynamics of the AOKR pulse scheme the characterizationof the BEC initial state and its evolution is done The finite momentum spread ofthe BEC is theoretically proposed to affect the sensitivity newline newline