Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Bose-Einstine condensation in a dilute gas: Measurement of energy and ground state occupation



J R. Ensher, Deborah S. Jin, M R. Matthews, C E. Wieman, Eric A. Cornell


We measure the ground state occupation and energy of a dilute Bose gas as a function of temperature. 87Rb atoms are collected in an optical trap, loaded into a purely magnetic trap, and then evaporated cooled through the Bose-Einstein condensation phase transition. The ground state fraction shows good agreement with the predictions for an ideal Bose gas in a 3-d harmonic potential. The measured transition temperature is 0.94(5)To, where To is the value for a non-interacting gas in the thermodynamic limit. We determine the energy form a model-independent analysis of the spatial absorption profile, after ballistic expansion, of the atom cloud. We observe a distinct change in slope of the energy-temperature curve near the transition, which indicates a sharp feature in the specific heat.
Physical Review Letters


Bose-Einstein condensation, ground-state fraction, specific heat


Ensher, J. , Jin, D. , Matthews, M. , Wieman, C. and Cornell, E. (2021), Bose-Einstine condensation in a dilute gas: Measurement of energy and ground state occupation, Physical Review Letters (Accessed May 28, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created October 12, 2021