Nona Semana Integrada do Instituto de Física de São Carlos

Critical behavior of an ultracold, non-uniform Bose gas: a computational study

Não agendado

20m

Iniciação Científica

Palestrante

Sr. Marcos Miotti (São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil)

Descrição

Research on critical phenomena is a current trend in Physics, due especially to its multidisciplinary character. A classical example of critical phenomenon is the Bose-Einstein condensation (BEC), which can observed in dilute gases below microkelvin temperatures. (1) In those experiments, the gas samples are usually trapped in harmonic potentials. Though technically simple, that confinement makes the density of the samples inhomogeneous, thus the standard analysis of criticality does not hold. Nonetheless, the global-variable method (2) allows us to identify a pair of canonical variables in a harmonical system that are equivalent to pressure and volume in a uniform system. Therefore, a harmonical system can be treated as uniform in the global-variable picture. For that reason, we used that approach to study theoretically the thermodynamic properties of a harmonically confined rubidum-87 gas around its BEC temperature. Those properties have been determine by self-consistent calculations using the Hartree-Fock approximation in the Thomas-Fermi limit, which describes corretly the thermodynamic properties of $10^4$~$10^6$-atom systems. (3) Those results will support our ongoing experimental study and they will be presented during the SIFSC 2019.

Referências

1 KETTERLE, W.; DURFEE, D.S.; STAMPER-KUN, D. M. Making, probing and understanding Bose-Einstein condensates. In: INTERNATIONAL SCHOOL OF PHYSICS "ENRICO FERMI", 1998, Varenna. Proceedings.... Amsterdam: IOS. v. 140, p. 67-176, 1999.
2 ROMERO-ROCHÍN, V. Equation of state of an interacting bose gas confined by a harmonic trap: the role of the “harmonic” pressure. Physical Review Letters, v. 94, n. 13, p. 130601-1-130601-4, Apr. 2005.
3 GERBIER, F. et al. Experimental study of the thermodynamics of an interacting trapped Bose-Einstein condensed gas. Physical Review A, v. 70, n. 1, p. 013607-1-013607-10, July 2004.