  We report the first observation of mechanical momentum transferred to atoms
and molecules upon application of crossed electric and magnetic fields. We
identify this momentum as the microscopic analogue of the classical Abraham
force. Several predictions of additional magneto-electrically induced
mechanical momentum are addressed. One of them, proposed to result from the
interaction with the quantum vacuum, is experimentally refuted, others are
found to be currently below experimental detection.

Optics;Atomic Physics