Title : 
Bound state in continuum: Proposal for realization in cold atoms 

Speaker  :  Prof. Bimalendu Deb, IACS, Kolkata 
Date  :  March 15, 2017 
Time  :  4:00 PM 
Venue  :  Lecture Hall1 
Abstract  : 
A bound state in continuum (BIC) is a counterintuitive concept first introduced by von Neumann and Wigner more than 80 years ago [1], showing that a BIC can exist due to destructive interference of the outgoing Schroedinger waves scattered by an appropriately designed potential. Over the years, the theoretical approach of von Neumann and Wigner has undergone extensions and modifications [2–4]. In recent times, it has attracted renewed research interests [5] with possible experimental realization [6]. In this colloquium, firstly we will introduce the concept of BIC with a historical perspective; and then show that it is possible to generate BIC in cold atoms with lasers in the presence of a magnetic Feshbach resonance [7]. The proposed coldatom BIC can be realized by forming an appropriate coherent superposition of molecular bound states above the threshold of twoatom collisional continuum. The BIC state becomes effectively decoupled from the continuum, and hence in the absence of other damping processes this state is nondecaying. We will discuss possible experimental signatures of coldatom BIC and its potential applications in continuumbound coherent spectroscopy. References [1] J. von Neumann and E. Wigner, Phys. Z. 30, 465 (1929). [2] L. Fonda and R. G. Newton, Ann. Phys. (NY) 10, 490 (1960). [3] F. H. Stillinger and D. R. Herrick, Phys. Rev. A 11, 446 (1975). [4] H. Friedrich and D. Wintgen, Phys. Rev. A 32, 3231 (1985). [5] A. G. Smart, Phys. Today 66, 14 (2013). [6] C. W. Hsu et al., Nature (London) 499, 188 (2013). [7] B. Deb and G. S. Agarwal, Phys. Rev. A 90, 063417 (2014) [Editors\' suggestion]. 