Quasipure Bose-Einstein Condensate Immersed in a Fermi Sea

Abstract

We report the observation of coexisting Bose-Einstein condensate (BEC) and Fermi gas in a magnetic trap. With a very small fraction of thermal atoms, the ${}^{7}\mathrm{Li}$ condensate is quasipure and in thermal contact with a ${}^{6}\mathrm{Li}$ Fermi gas. The lowest common temperature is $0.28\ensuremath{\mu}\mathrm{K}\ensuremath{\simeq}0.2(1){T}_{\mathrm{C}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.2(1){T}_{\mathrm{F}}$ where ${T}_{\mathrm{C}}$ is the BEC critical temperature and ${T}_{\mathrm{F}}$ the Fermi temperature. The ${}^{7}\mathrm{Li}$ condensate has a one-dimensional character.