  We propose a long-lived and rapidly accessible quantum memory unit, for which
the operational Hilbert space is spanned by states involving the two
macroscopically occupied hyperfine levels of a miscible binary atomic
Bose-Einstein condensate and the Rydberg state of a single atom. It is shown
that an arbitrary qubit state, initially prepared using a flux qubit, can be
rapidly transferred to and from the trapped atomic ensemble in approximately 10
ns and with a large fidelity of 97%, via an effective two-photon process using
an external laser for the transition to the Rydberg level. The achievable
ultrafast transfer of quantum information therefore enables a large number of
storage and retrieval cycles from the highly controllable quantum optics setup
of a dilute ultracold gas, even within the typically very short flux qubit
lifetimes of the order of microseconds.
