Typical application scenarios:

• System Design:
  VPItoolkit QKD serves as a test bed for developing and evaluating various implementation options for QKD systems and sub-systems (e.g. pulse preparation, signal recovery and filtering).
   
• Study of co-existence scenarios:
  Exploiting the powerful model libraries coming with VPItransmissionMaker Optical Systems, the toolkit allows to investigate various deteriorative effects such as Raman scattering and cross-talk from classical channels.
   
• Account of component imperfections:
  The toolkit offers freedom and flexibility for modeling a wide range of component imperfections by inheriting the versatile numerical approach of VPItransmissionMaker Optical Systems, including e.g. thermal noise, ADC quantization noise, biased beam splitting ratios, RIN, phase noise, limited common mode rejection, dark count rates, after pulsing, and dead time.
   
• Optimization of system parameters:
  In-build sweep and scripting functionality offers a convenient way to optimize simulations parameters such as modulation amplitude, photons per pulse, filter bandwidth, BB84 basis probability, symbol rate.
   

Weak-coherent prepare-and-measure DV-QKD
 

• Single photon counting

• Differential phase shift keying transmitter and receiver

• Polarization, time/phase & T12 basis BB84 transmitters & receivers

• Sifting

• Random number generator for decoy state BB84, e.g. T12

• Secret fraction estimator for T12