Bose-Einstein Condensation of Chromium

TLDR

The chromium condensate is produced by novel cooling techniques tailored to its electronic and magnetic properties, culminating in forced evaporative cooling of $^{52}$Cr atoms in a crossed optical dipole trap. A Bose–Einstein condensate of more than 50 000 $^{52}$Cr atoms is achieved at a critical temperature of ≈700 nK, evidenced by a two‑component velocity distribution and the appearance of a nearly pure condensate.

Abstract

We report on the generation of a Bose-Einstein condensate in a gas of chromium atoms, which have an exceptionally large magnetic dipole moment and therefore underlie anisotropic long-range interactions. The preparation of the chromium condensate requires novel cooling strategies that are adapted to its special electronic and magnetic properties. The final step to reach quantum degeneracy is forced evaporative cooling of $^{52}\mathrm{Cr}$ atoms within a crossed optical dipole trap. At a critical temperature of ${T}_{c}\ensuremath{\approx}700\text{ }\text{ }\mathrm{nK}$, we observe Bose-Einstein condensation by the appearance of a two-component velocity distribution. We are able to produce almost pure condensates with more than 50 000 condensed $^{52}\mathrm{Cr}$ atoms.