Prime factoring using a Josephson phase-qubit architecture: $15 = 3*5$

We demonstrate a compiled version of Shor's algorithm using a quantum processor. The processor consists of ``off-the-shelf" components: qubits and resonators arranged in the ReZQu architecture. We have performed the algorithm for N=15 and the period r=2. The required two and three qubit entanglement is observed during the computation, which exemplifies the quantum nature of the algorithm.