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arXiv · 1512.09218

Coupling qubits in circuit-QED cavities connected by a bridge qubit

Mun Dae Kim·Jaewan Kim
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Abstract

We analyze a coupling scheme for qubits in different cavities of circuit-QED architecture. In contrast to the usual scheme where the cavities are coupled by an interface capacitance we employ a bridge qubit connecting cavities to mediate two-qubit coupling. This active coupling scheme makes it possible to switch on/off and adjust the strength of qubit-qubit coupling, which is essential for scalability of quantum circuit. By transforming the Hamiltonian we obtain an exact expression of two-qubit coupling in the rotating-wave approximation. For the general case of $n$ qubits the Hamiltonian can produce the W state as an eigenstate of the system. We calculate the decay rate of the coupled qubit-resonator system to find that it is viable in real experiments.

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Mun Dae Kim, Jaewan Kim. 2016-01-21. Coupling qubits in circuit-QED cavities connected by a bridge qubit. https://doi.org/10.1103/physreva.93.012321

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