arXiv subjects

A. Rakonjac

Publications and source records attributed to A. Rakonjac.

4 recordsLinked to original sources

arXiv2016

Measuring the disorder of vortex lattices in a Bose-Einstein condensate

We report observations of the formation and subsequent decay of a vortex lattice in a Bose-Einstein condensate confined in a hybrid optical-magnetic trap. Vortices are induced by rotating the anharmonic magnetic potential that provides confinement in the horizontal plane. We present simple numerical techniques based on image analysis to detect vortices and analyze their distributions. We use these methods to quantify the amount of order present in the vortex distribution as it transitions from a disordered array to the energetically favorable ordered lattice.

physics.atom-ph↗

arXiv2015

Quantum reflection of bright solitary matter-waves from a narrow attractive potential

We report the observation of quantum reflection from a narrow, attractive, potential using bright solitary matter-waves formed from a 85Rb Bose-Einstein condensate. We create narrow potentials using a tightly focused, red-detuned laser beam, and observe reflection of up to 25% of the atoms, along with the trapping of atoms at the position of the beam. We show that the observed reflected fraction is much larger than theoretical predictions for a narrow Gaussian potential well; a more detailed model of bright soliton propagation, accounting for the generic presence of small subsidiary intensity maxima in the red-detuned beam, suggests that these small intensity maxima are the cause of this enhanced reflection.

physics.atom-ph↗

arXiv2012

A versatile laser system for experiments with cold atomic gases

We describe a simple and compact architecture for generating all optical frequencies required for the laser cooling, state preparation and detection of atoms in an ultracold rubidium-87 experiment from a single 780 nm laser source. In particular, repump light $\sim$ 6.5 GHz away from the cooling transition is generated by using a high-bandwidth fiber-coupled eletro-optical modulator (EOM) in a feedback loop configuration. The looped repump light generation scheme solves the problem of the limited power handling capabilities characteristics of fiber EOMs. We demonstrate the functionality of the system by creating a high atom number magneto-optical trap (MOT)

physics.atom-ph↗

arXiv2012

A laser based accelerator for ultracold atoms

We present first results on our implementation of a laser based accelerator for ultracold atoms. Atoms cooled to a temperature of 420 nK are confined and accelerated by means of laser tweezer beams and the atomic scattering is directly observed in laser absorption imaging. The optical collider has been characterized using Rb87 atoms in the |F=2,mF=2> state, but the scheme is not restricted to atoms in any particular magnetic substates and can readily be extended to other atomic species as well.

cond-mat.quant-gas↗