Bose-Einstein Condensation at Gakushuin University
Last updated on Aug 8, 2000
In the night of 19 July 2000, we achieved BEC with rubidium atoms!
(a) (b)(c)
Absorption images of rubidium atoms taken after 20-ms expansion from a magnetic trap. (a)Thermal cloud with a temperature of about 500nK (just before phase transition). (b)Bimodal structure of thermal cloud and Bose-condensate. (c)pure Bose-condensate. The final rf frequency is (a)1.24MHz, (b)1.23MHz, and (c)1.22MHz. The field of view is 1mm x 1mm.
The experimental details are as follows:
atomic species: 87Rb, |F MF> = |2 +2>
loading: double MOT system with novel cw loading
magnetic trap: a cloverleaf magnetic trap (B'=220G/cm, B''=125G/cm2 at I =375A)
loading time: 5 s
initial number of atoms in UHV MOT: 1 x 109
initial number of atoms in magnetic trap: 7 x 108
lifetime of magnetic trap: 90s
evaporation time: 25 s (from 50MHz to around 1.2MHz)
transition temperature: about 500 nK
number of condensed atoms: about 105
total time to create a BEC: about 35s (including loading, adiabatic compression, and evaporative cooling)
(Further details will be appear in this web page in near future)
Some pictures of the experimental apparatus
Whole apparatus |
Double MOT system |
Upper MOT chamber |
Lower MOT glass cell and cloverleaf coil |
The work that led to BEC has been advanced by the efforts of:
Kenichi Ito
Ryo Namiki
Students contributing to this work have included:
Katsutoshi Kondo
Yuichi Sasaki
Tsunetoshi Sakano
Soichiro Nakamura
The senior staffs involved in this work are:
Yoshio Torii (research associate)
Takuya Hirano (associate professor)
If you have any comments or questions, please mail to yoshio.torii@gakushuin.ac.jp
BEC homepage hirano-lab top page