We employ a correlated many-body approach to study Bose-Einstein condensation of a magnetically trapped gas of 7Li atoms. The properties of a trapped gas are strongly influenced by the attractive interactions and two-body correlations. The correlations lower the interaction energy. The lowlying collective frequencies have also been calculated. In addition we explore the frequency of surface modes as a function of angular momentum. © 2009 Springer Science+Business Media, LLC.

TAPAN DAS

Ancient Indian History and Culture

B CHAKRABARTI

P K DEBNATH

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Journal of Low Temperature Physics

We study the properties of Bose-Einstein condensates with the realistic van der Waals two-body interaction for large numbers of trapped atoms, solving the many-body Schrödinger equation by the potential harmonic expansion method. The effect of different C6 parameters has been critically examined, starting from very few to 14000 atoms to analyze and justify the idea of a shape-independent approximation. It is found that the condensate properties almost remain unchanged when the number of atoms are quite small (∼100), in good agreement with earlier results of Blume and Greene [Phys. Rev. A 63, 063601 (2001)], but we observe the appreciable effect of a long attractive tail when N is large, even in the low-density limit. The above reference considered only 20 atoms which is far from a real experimental situation. Our calculation gives a realistic scenario which justifies the use of a shape-dependent two-body interaction in many-body theories. © 2008 The American Physical Society.

Physical Review A - Atomic, Molecular, and Optical Physics

Shape-independent approximation for Bose-Einstein condensates interacting through a van der Waals potential

The stability of trapped interacting bosons with attractive interactions is studied using an approximate many-body calculation. Instead of using the traditional hyperspherical harmonics expansion method we prescribe a potential harmonics expansion method (PHEM). The justification of the use of PHEM in connection with dilute condensates is presented. The choice of a correlation function is justified as it correctly reproduces the short-range two-body correlation in the wavefunction as also the correct value of the s-wave scattering length (as). Applications to 7Li and 85Rb condensates with the realistic van der Waals interaction give good agreement with the Rice and JILA experiments, respectively. The JILA experiment used controlled collapse of the 85Rb condensate for different values of as. Our calculations agree with the experimental results within the experimental error bars. © 2007 IOP Publishing Ltd.

Journal of Physics B: Atomic, Molecular and Optical Physics

An approximate many-body calculation for trapped bosons with attractive interaction

We investigate Bose-Einstein condensates (BEC) containing a large number of bosonic atoms interacting via a finite-range semirealistic interatomic interaction. Ground state properties for an increasing number of atoms in the condensate have been calculated using a modification of the potential harmonic expansion method (including a short range correlation function in the expansion basis) to solve the many-body Schrödinger equation. An improved numerical algorithm for the calculation of the potential matrix elements permits us to have up to 14000 atoms in the condensate. Although our approach is approximate and justified for dilute condensates, our results agree well with available diffusion Monte Carlo results for the same case. The ground state energies also agree well with those by the Gross-Pitaevskii equation method for up to 100 particles in the trap and become gradually larger than the latter (up to 5% for 14000 atoms). The difference is attributed to the effects of finite range interatomic interaction and two-body correlations. Our approach presents a clear physical picture of the condensate, being computationally economical at the same time. © 2007 The American Physical Society.

Behavior of a Bose-Einstein condensate containing a large number of atoms interacting through a finite-range interatomic interaction

The T=0 properties of a Bose-Einstein condensate (BEC), consisting of A atoms (bosons) trapped by an external field, were investigated. An ab initio treatment of the Schrödinger equation involves 3(A-1) degrees of freedom for the relative motion. The potential matrix elements involved integrals over only three angle variables, leading to an immense reduction in the complexity of the numerical procedure for A particles. It was noticed that many-body results converged towards the mean field results as the particle number increased.

Journal	Data powered by TypesetJournal of Low Temperature Physics
Publisher	Data powered by TypesetSPRINGER/PLENUM PUBLISHERS
ISSN	0022-2291