Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

126 Biennial Report 2005-07integrals in the Hamiltonian. It also reveals that the sign of the low-field persistent currents cannotbe predicted precisely which in fact corroborates the experimental findings.SN Karmakar, Santanu K Maiti, Jayeeta ChowdhuryTCMP4.2.1.2 Specific heat of Bosons in a latticeThe specific heat of bosons (C v ) in a simple cubic lattice has been studied for non-interacting andinteracting (in the Tonks gas limit) bosons. For both cases, the C v above the bose condensationtemperature shows considerable temperature dependence compared to that of free bosons. ForTonks gas, we find that the low-temperature specific heat increases as the system gets closer to theMott transition.AN Das, R Ramakumar†TCMP4.2.1.3 Studies of bosons in optical lattices in a harmonic potentialBose condensation and specific heat of non-interacting bosons in finite lattices in presence of harmonicpotentials have been studied in one, two, and three dimensions. We numerically diagonalizethe Hamiltonian to obtain the energy levels of the systems. Using the energy levels thus obtained,we investigate the temperature dependence, dimensionality effects, lattice size dependence, andevolution to the bulk limit of the condensate fraction and the specific heat. Some preliminaryresults on the specific heat of fermions in optical lattices are also presented. The results obtainedare contextualized within the current experimental and theoretical scenario.AN Das, R Ramakumar†TCMP4.2.1.4 Lattice bosons in quartic confinementWe have studied bose condensation of non-interacting bosons in finite lattices in quartic potentialsin one, two, and three dimensions. We investigate the dimensionality effects and quartic potentialeffects on single boson density of energy states, condensation temperature, condensate fraction, andspecific heat. The results obtained are compared with corresponding results for lattice bosons inharmonic traps.AN Das, R Ramakumar†TCMP4.2.1.5 Thermodynamic properties of Holstein polarons and the effects of disorderThe ground state and finite temperature properties of polarons are studied considering a two-siteand a four-site Holstein model by exact diagonalization of the Hamiltonian. The kinetic energy,Drude weight, correlation functions involving charge and lattice deformations, and the specific heat