Creation and manipulation of bound states in continuum with lasers: Applications to cold atoms and molecules

Abstract

We show theoretically that it is possible to create and manipulate a pair of bound states in continuum in ultracold atoms by two lasers in the presence of a magnetically tunable Feshbach resonance. These bound states are formed due to coherent superposition of two electronically excited molecular bound states and a quasi-bound state in ground-state potential. These superposition states are decoupled from the continuum of two-atom collisional states. Hence, in the absence of other damping processes they are non-decaying. We analyze in detail the physical conditions that can lead to the formation of such states in cold collisions between atoms, and discuss the possible experimental signatures of such states. An extremely narrow and asymmetric shape with a distinct minimum of photoassociative absorption spectrum or scattering cross section as a function of collision energy will indicate the occurrence of a bound state in continuum (BIC). We prove that the minimum will occur at an energy at which the BIC is formed. We discuss how a BIC will be useful for efficient creation of Feshbach molecules and manipulation of cold collisions. Experimental realizations of BIC will pave the way for a new kind of bound-bound spectroscopy in ultracold atoms.

26 pages 3 figures, typographical and other minor errors are corrected in version-2

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• Fano effect in an ultracold atom-molecule coupled system
• Suppressing deleterious effects of spontaneous emission in creating bound states in cold atom continuum
• A unified approach to $\Lambda$-, $\Xi$- and $V$-type systems with one continuum
• Observing S-Matrix Pole Flow in Resonance Interplay: Cold Collisions of Ultracold Atoms in a Miniature Laser-based Accelerator
• Stabilization of three-body resonances to bound states in a continuum
• Bound states in the continuum of fractional Schrödinger equation in the Earth's gravitational field and their effects in the presence of a minimal length: applications to distinguish ultralight particles