A quantum bus for superconducting qubits can be built with a resonance cavity. The hamiltonian for a system with qubit A, qubit B, and the resonance cavity or quantum bus connecting the two is H ^ ^ = H ^ ^ r + ∑ ∑ j = A , B H ^ ^ j + ∑ ∑ j = A , B h g i ( a ^ ^ † † σ σ ^ ^ − − j + a ^ ^ σ σ ^ ^ + j ) where H ^ ^ j = 1 2 ℏ ℏ ω ω j σ σ ^ ^ + j σ σ ^ ^ − − j is the single qubit hamiltonian, σ σ ^ ^ + j σ σ ^ ^ − − j is the raising or lowering operator for creating or destroying excitations in the j th qubit, and ℏ ℏ ω ω j is controlled by the amplitude of the D.C. and radio frequency flux bias.