Compact Decoy State Sources for QKD

Ever noticed how complex a decoy state source for prepare-and-measure BB84 and alike QKD can be - if it is composed of traditional components such as laser diodes in butterfly packages, and electro-optical modulators for phase and amplitude? Not talking about providing the random numbers for their driving...

What about a handheld sized, space-compatible design that can feed its photons directly into the opticla terminal of a QKD satellite? DLR funds a project that will investigate:

• a customized VCSEL-Array aounrd 800 nm, having indistinguishable wavelengths amongst the individual VCSEL that represents the decoy protocol states, and having individual, customizable polarizations: Michel Jetter , University of Stuttgart
• a high speed, space-suitable ceramics PCB electronics platform that drives the VCSEL array in speeds up to 10 GHz: Jens Mueller , TU Ilmenau
• a waveguide combiner for collecting all decoy protocol states in one single output channel, and a cigarette box sized butterfly package that also hosts the precise thermal management of the design: Fraunhofer IOF

We will start on the 1st of August and shall be able to show first prototypes in 2022! Stay tuned, the race for QKD is on.