Transduction of quantum information from charge qubit to nanomechanical cat-state.

We suggest a nanoelectromechanical setup and corresponding time-protocol of its manipulation by which we transduce quantum information from charge qubit to nanomechanical cat-state. The setup is based on the AC Josephson effect between bulk superconductors and mechanically vibrating mesoscopic superconducting island in the regime of the Cooper pair box. Starting with a pure state with quantum information initially encoded into superposition of the Cooper pair box states, applying a specially tailored time-protocol upon bias voltage and gate electrodes, we obtain a new pure state with information finally encoded into superposition of nanomechanical coherent states constituting the cat-state. This performance is achieved using quantum entanglement between electrical and mechanical states. Nanomechanical cat-states serve as a "storage" of quantum information, motivated by significantly longer decoherence time with respect to the charge qubit states, from which the information can be transdued back to the charge qubit applying the reverse time-protocol. • Superconducting NEMS featuring charge qubit is resonantly coupled to nanomechanics by the AC Josephson effect. • Time protocol of NEMS setup is used to build cat-states consisting of nanomechanical coherent states. • Quantum information is encoded into pure charge qubit state and transduced into pure nanomechanical cat-state using the entanglement between electrical and nanomechanical states. [ABSTRACT FROM AUTHOR]