  By harnessing the superposition and entanglement of physical states, quantum
computers could outperform their classical counterparts in solving problems of
technological impact, such as factoring large numbers and searching databases.
A quantum processor executes algorithms by applying a programmable sequence of
gates to an initialized register of qubits, which coherently evolves into a
final state containing the result of the computation. Simultaneously meeting
the conflicting requirements of long coherence, state preparation, universal
gate operations, and qubit readout makes building quantum processors
challenging. Few-qubit processors have already been shown in nuclear magnetic
resonance, cold ion trap and optical systems, but a solid-state realization has
remained an outstanding challenge. Here we demonstrate a two-qubit
superconducting processor and the implementation of the Grover search and
Deutsch-Jozsa quantum algorithms. We employ a novel two-qubit interaction,
tunable in strength by two orders of magnitude on nanosecond time scales, which
is mediated by a cavity bus in a circuit quantum electrodynamics (cQED)
architecture. This interaction allows generation of highly-entangled states
with concurrence up to 94%. Although this processor constitutes an important
step in quantum computing with integrated circuits, continuing efforts to
increase qubit coherence times, gate performance and register size will be
required to fulfill the promise of a scalable technology.
