Quantum key distribution using a triggered quantum dot source emitting near 1.3μm

We report the distribution of a cryptographic key, secure from photon number splitting attacks, over $35\mathrm{km}$ of optical fiber using single photons from an InAs quantum dot emitting $\sim 1.3\mu \mathrm{m}$ in a pillar microcavity. Using below GaAs-bandgap optical excitation, we demonstrate suppression of multiphoton emission to 10% of the Poissonian level without detector dark count subtraction. The source is incorporated into a phase encoded interferometric scheme implementing the BB84 protocol for key distribution over standard telecommunication optical fiber. We show a transmission distance advantage over that possible with (length-optimized) uniform intensity weak coherent pulses at $1310\mathrm{nm}$ in the same system.