  Interaction of a control and a signal field with an ensemble of three-level
atoms allows direct mapping of the quantum state of the signal field into long
lived coherences of an atomic ground state. For a vapor of cesium atoms, using
Electromagnetically Induced Transparency (EIT) and Zeeman coherences, we
compare the case where a tunable single-sideband is stored independently of the
other one to the case where the two symmetrical sidebands are stored using the
same transparency window. We study the conditions in which simultaneous storage
of two non-commuting variables carried by light and subsequent read-out is
possible. We show that excess noise associated with spontaneous emission and
spin relaxation is small, and we evaluate the quantum performance of our memory
by measuring the signal transfer coefficient T and the conditional variance V
and using the T-V criterion as a state independent benchmark.
