Arpita Rakshit

Ion-atom cold collision: Formation of cold molecular ion by radiative processes

Molecular ions are important for a variety of fundamental studies in physics. For instance, it is proposed that cold molecular ions would be useful for measuring electron dipole moment (EDM) [1, 2]. Study of cold molecular ions has relevance in diverse areas such as metrology [3, 4] and astrochemistry [5]. Recently, molecular ions are cooled into ro-vibrational ground states by all optical [6], laser and sympathetic cooling methods [7, 8]. A large variety of diatomic and triatomic molecular ions are also cooled by sympathetic method [9–11]. Other methods such as photoassociative ionisation [12–16], buffer gas [17], and rotational cooling [18] have been widely used for producing low energy molecular ions. Since cooling of neutral atoms and atomic ions down to sub-milliKelvin temperature regime is possible with currently available technology of laser cooling, it is now natural to ask ourselves: Is it possible to form cold molecular ion by atom-ion cold collision? Recent progress in developing hybrid traps [19–22] where both atomic ions and neutral atoms can be simultaneously confined provides new opportunity for exploring ion-atom quantum dynamics and charge transfer reactions at ultralow

Suppression of power broadening in strong-coupling photoassociation in the presence of a Feshbach resonance

The photoassociation (PA) spectrum is analysed in the presence of a magnetic Feshbach resonance. A nonperturbative solution of the problem yields analytical expressions for PA linewidth and shift which are applicable for arbitrary PA laser intensity and magnetic field tuning of Feshbach resonance. We show that by tuning the magnetic field close to the Fano minimum, it is possible to suppress power broadening at increased laser intensities. This occurs due to quantum interference of PA transitions from unperturbed and perturbed continuum. Line narrowing at high laser intensities is accompanied by large spectral shifts. We briefly discuss the important consequences of line narrowing in cold collisions.

Interactions and low-energy collisions between an alkali ion and an alkali atom of a different nucleus

We study theoretically interaction potentials and low-energy collisions between different alkali atoms and alkali ions. Specifically, we consider systems such as X + , where X( is either Li(Cs+) or Cs(Li+), Na(Cs+) or Cs(Na+) and Li(Rb+) or Rb(Li+). We calculate the molecular potentials of the ground and first two excited states of these three systems using a pseudopotential method and compare our results with those obtained by others. We derive ground-state scattering wave functions and analyze the cold collisional properties of these systems for a wide range of energies. We find that, in order to get convergent results for the total scattering cross sections for energies of the order 1 K, one needs to take into account at least 60 partial waves. The low-energy scattering properties calculated in this paper may serve as a precursor for experimental exploration of quantum collisions between an alkali atom and an alkali ion of a different nucleus.

A model study on atom–atom interactions with large scattering length in quasi-two dimensional traps

We carry out a model study on two-atom interactions and bound states in quasi-two dimensional traps. The interactions are modeled by two-parameter potentials with parameters being the range

Formation of cold molecular ions by radiative processes in cold ion-atom collisions

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Optical Feshbach resonances through a molecular dark state: Efficient manipulation ofp-wave resonances in fermionicYb171atoms

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Quantum effects at low-energy atom–molecule interface

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