• Barnali Chakrabarti

      Articles written in Pramana – Journal of Physics

    • Application of potential harmonic expansion method to BEC: Thermodynamic properties of trapped23Na atoms

      Anasuya Kundu Barnali Chakrabarti Tapan Kumar Das

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      We adopt the potential harmonics expansion method for anab initio solution of the many-body system in a Bose condensate containing interacting bosons. Unlike commonly adopted mean-field theories, our method is capable of handling two-body correlation properly. We disregard three- and higher-body correlations. This simplification is ideally suited to dilute Bose Einstein condensates, whose number density is required to be so small that the interparticle separation is much larger than the range of two-body interaction to avoid three- and higher-body collisions, leading to the formation of molecules and consequent instability of the condensate. In our method we can incorporate realistic finite range interactions. We calculate energies of low-lying states of a condensate containing23Na atoms and some thermodynamical properties of the condensate.

    • Quality of potential harmonics expansion method for dilute Bose–Einstein condensate

      Anasuya Kundu Barnali Chakrabarti

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      We present and examine an approximate but ab initio many-body approach, viz., potential harmonics expansion method (PHEM), which includes two-body correlations for dilute Bose–Einstein condensates. Comparing the total ground state energy for three trapped interacting bosons calculated in PHEM with the exact energy, the new method is shown to be very good in the low density limit which is necessary for achieving Bose–Einstein condensation experimentally.

    • Spectral properties of supersymmetric shape invariant potentials

      Barnali Chakrabarti

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      We present the spectral properties of supersymmetric shape invariant potentials (SIPs). Although the folded spectrum is completely random, unfolded spectrum shows that energy levels are highly correlated and absolutely rigid. All the SIPs exhibit harmonic oscillator-type spectral statistics in the unfolded spectrum. We conjecture that this is the reflection of shape invariant symmetry.

    • Use of supersymmetric isospectral formalism to realistic quantum many-body problems

      Barnali Chakrabarti

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      We propose a novel mathematical approach for the calculation of resonances in weakly bound systems. For any potential, families of strictly isospectral potentials (with very different shape) having desirable and adjustable features can be generated. For systems having no bound ground state, an isospectral potential with a bound state in the continuum is possible. The quasi-bound state in the original shallow potential will be effectively trapped in the deep well of the isospectral family, facilitating more accurate calculation of resonance energy. Application to 6He, 6Li and 6Be yield excellent results. Another application is the calculation of Efimov states in weakly bound three-body system. We present the result of 4He trimer, where the first excited state is claimed to be an Efimov state.

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