Interfacing Quantum-Optical and Solid-State Qubits

We present a generic model of coupling quantum-optical and solid-state qubits, and the corresponding transfer protocols. The example discussed is a trapped ion coupled to a charge qubit (e.g., Cooper pair box). To enhance the coupling and to achieve compatibility between the different experimental setups we introduce a superconducting cavity as the connecting element.

Figure 1

Schematic coupling circuit of the charge qubit and trapped ion. Top: the coupling via a cavity. The voltage at the electrode is balanced by a filtering circuit. Bottom left: coherent states of the motional mode. Bottom right: energy of charge qubit vs gate voltage.