  Hybrids consisting of macroscopic superconducting circuits and microscopic
components, such as atoms and spins, have the potential of transmitting an
arbitrary state between different quantum species, leading to the prospective
of high-speed operation and long-time storage of quantum information. Here we
propose a novel hybrid structure, where a neutral-atom qubit directly
interfaces with a superconducting charge qubit, to implement the qubit-state
transmission. The highly-excited Rydberg atom located inside the gate capacitor
strongly affects the behavior of Cooper pairs in the box while the atom in the
ground state hardly interferes with the superconducting device. In addition,
the DC Stark shift of the atomic states significantly depends on the
charge-qubit states. By means of the standard spectroscopic techniques and
sweeping the gate voltage bias, we show how to transfer an arbitrary quantum
state from the superconducting device to the atom and vice versa.
