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

Deb, Bimalendu; Agarwal, G. S.

doi:10.1103/physreva.90.063417

Cited by 14 publications

(10 citation statements)

References 60 publications

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“…More recently, Friedrich-Wintgen BICs have been studied in continuum shell models 121 , cold-atom collisions 122 , 2D topological insulators with defect 123 , and for quantum graphs 124 , quantum billiards 125 , or impurity atoms 126,127 attached to leads. In acoustics they have been studied in multi-resonant cavities 103,128 .…”

Section: Friedrich-wintgen Bic (Through Coupled Resonances)mentioning

confidence: 99%

Bound states in the continuum

et al. 2016

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Bound states in the continuum are waves that, defying conventional wisdom, remain localized even though they coexist with a continuous spectrum of radiating waves that can carry energy away. Their existence was first proposed in quantum mechanics and, being a general wave phenomenon, later identified in electromagnetic, acoustic, and water waves. They have been studied in a wide variety of material systems such as photonic crystals, optical waveguides and fibers, piezoelectric materials, quantum dots, graphene, and topological insulators. This Review describes recent developments in this field with an emphasis on the physical mechanisms that lead to these unusual states across the seemingly very different platforms. We discuss recent experimental realizations, existing applications, and directions for future work.

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Section: Friedrich-wintgen Bic (Through Coupled Resonances)mentioning

confidence: 99%

Bound states in the continuum

et al. 2016

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“…The Fano effect in the photoassociation (PA) of cold atoms in the presence of a magnetic Feshbach resonance has been theoretically predicted previously 26,27 . This effect has been shown to be useful for the creation of a bound state in a continuum 28 and may thereby find important applications in the coherent manipulation of atommolecule coupled systems. Although a Fano-like asymmetric spectral profile has been observed in PA 29 , a magneto-optically tunable Fano effect in an atom-molecule coupled system is yet to be experimentally confirmed.…”

Section: Introductionmentioning

confidence: 99%

Fano effect in an ultracold atom-molecule coupled system

Gao

et al. 2019

Phys. Rev. A

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The Fano effect or Fano resonance with a characteristically asymmetric line shape originates from quantum interference between direct and indirect transition pathways in continuumbound coupled systems, and is a ubiquitous phenomenon in atomic 1,2 , molecular 3 , nuclear 4,5 and solid-state physics 6-8 . In optical nanoscale structures, the Fano effect has wide-ranging applications that include optical filtering 9 , sensing 10 , all-optical switching 11 , quantum interferometry 12 and nonlinear optics 13 , and this opens new avenues for photonic devices. The emergent area of ultracold atomic and molecular gases presents an ideal platform for studying Fano resonances, since the physical parameters of these gases can be extensively tuned with high precision using external fields. However, an experimental demonstration of the Fano effect in hybridized atom-molecular coupled systems has remained elusive. Here, we report on observations of the Fano effect in molecular spectra obtained by photoassociation (PA) near a d-wave Feshbach resonance. This effect occurs due to quantum interference in PA transitions involving the continuum of atom-atom scattering states, the underlying Feshbach and photoassociated excited bound molecular states. We measure the variation in atom loss rate with an external magnetic field close to the Feshbach resonance in the presence of PA laser, and thereby clearly demonstrate the Fano effect. Our results further reveal that the Fano effect has significant influence on spectral shifts. Based on Fano's method, we develop a theory that explains the observed experimental results relatively well. Our theoretical formulation takes into account quantum interference between or among multiple transition pathways and between inelastic channels. Our results present a novel method for tuning the collisional interaction strength with laser light using Fano resonance.

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“…With the recent advent of high-precision spectroscopy and coherent control of ultracold atoms and molecules, the realization of a BIC for ultracold atoms appears to be promising. Recently, the creation of a BIC by magneto-optically controlling ultracold collisions of atoms has been proposed by two of us [29]. This proposal has made use of two excited molecular states without considering any spontaneous emission from these states.…”

Section: Introductionmentioning

confidence: 99%

Suppressing deleterious effects of spontaneous emission in creating bound states in cold atom continuum

Naskar¹,

Sardar²,

Deb³

et al. 2019

J. Phys. B: At. Mol. Opt. Phys.

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In a previous paper [B. Deb and G. S. Agarwal, Phys. Rev. A 90, 063417 (2014)], it was theoretically shown that, magneto-optical manipulation of low energy scattering resonances and atom-molecule transitions could lead to the formation of a bound state in continuum (BIC), provided there is no spontaneous emission. We find that even an exceedingly small spontaneous decay from exited molecular states can spoil the BIC. In this paper, we show how to circumvent the detrimental effect of spontaneous emission by making use of vacuum-induced coherence (VIC) which results in the cancellation or suppression of spontaneous emission. VIC occurs due to the destructive interference between two spontaneous decay pathways. An essential condition for VIC is the non-orthogonality of the transition dipole moments associated with the decays. Furthermore, the interference between decay pathways requires that the spacing between the two decaying states must be comparable to or smaller than the square root of the product of the two spontaneous linewidths. We demonstrate that these conditions can be fulfilled by microwave dressing of two appropriately chosen molecular excited states, opening a promising prospect for the experimental realization of BIC of cold atoms.

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

Cited by 14 publications

References 60 publications

Bound states in the continuum

Bound states in the continuum

Fano effect in an ultracold atom-molecule coupled system

Suppressing deleterious effects of spontaneous emission in creating bound states in cold atom continuum

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