Quantum cryptography with highly entangled photons from semiconductor quantum dots.

Semiconductor quantum dots are capable of emitting polarization entangled photon pairs with ultralow multipair emission probability even at maximum brightness. Using a quantum dot source with a fidelity as high as 0.987(8), we implement here quantum key distribution with an average quantum bit error rate as low as 1.

High power picosecond parametric mid-IR source tunable between 1.7 and 2.6 μm.

A high-average-power wavelength-tunable picosecond mid-IR source based on parametric downconversion has been developed. The conversion system consists of two stages, optical parametric generator and optical parametric amplifier (OPA), which are pumped by an Yb:YAG thin-disk laser operated at 77 kHz repetition rate, 1030 nm wavelength, and pulse duration down to 1.3 ps.