Single photons and entangled photons from a quantum dot

We present an efficient source of indistinguishable single photons based on a pulsed excitation of a self-assembled InAs/GaAs quantum dot embedded in a three-dimensional micropost microcavity. The probability of generating two photons for the same pulse is reduced to 2%, compared to a Poisson-distributed source of the same intensity. An extension of this technique can be used to generate entangled photons. This photon source is crucial for practical implementations of quantum key distribution, as well as for quantum computation and networking based on photonic qubits.