Measuring the heat capacity in a Bose-Einstein condensation using global variables

Year: 2014

Authors: Shiozaki RF., Telles GD., Castilho P., Poveda-Cuevas FJ., Muniz SR., Roati G., Romero-Rochin V., Bagnato VS.

Autors Affiliation: Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Paulo, Brazil; Univ Florence, INO CNR, Sesto Fiorentino, Italy; Univ Florence, Dipartamento Fis, LENS, Sesto Fiorentino, Italy; Univ Nacl Autonoma Mexico, Inst Fis, Mexico City 01000, DF, Mexico.

Abstract: Phase transitions are well understood and generally followed by the behavior of the associated thermodynamic quantities, such as in the case of the lambda-point superfluid transition of liquid He, which is observed in its heat capacity. In the case of a trapped Bose-Einstein condensate, the heat capacity cannot be directly measured. In this work, we present a technique capable of determining the global heat capacity from the density distribution of a weakly interacting gas trapped in an inhomogeneous potential. This approach represents an alternative to models based on the local density approximation. By defining a pair of global conjugate variables, we determine the total internal energy and its temperature derivative, the heat capacity. We then apply the technique to a trapped Rb-87 BEC, and a lambda-type transition dependent on the atom number is observed, and the deviations from the noninteracting, ideal gas case are discussed. Finally, we discuss the chances of using this method to study the heat capacity at T –> 0.

Journal/Review: PHYSICAL REVIEW A

Volume: 90 (4)      Pages from: 43640-1  to: 43640-5

More Information: We thank Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP), and Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) for the funding. K. Farias and M. Caracanhas are acknowledged for technical support.
KeyWords: Harmonic Traps; Fermi Gas; Thermodynamics
DOI: 10.1103/PhysRevA.90.043640

Citations: 17
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