  The radioactive radium-225 ($^{225}$Ra) atom is a favorable case to search
for a permanent electric dipole moment (EDM). Due to its strong nuclear
octupole deformation and large atomic mass, $^{225}$Ra is particularly
sensitive to interactions in the nuclear medium that violate both time-reversal
symmetry and parity. We have developed a cold-atom technique to study the spin
precession of $^{225}$Ra atoms held in an optical dipole trap, and demonstrated
the principle of this method by completing the first measurement of its atomic
EDM, reaching an upper limit of $|$$d$($^{225}$Ra)$|$ $<$
$5.0\!\times\!10^{-22}$ $e \cdot$cm (95$\%$ confidence).
