Such a source of entangled photon pairs is applicable in different applications beyond QKD. The most obvious field of applications is teaching students in experimental quantum physics, using the source for entanglement experiments and for related software developments:

The EPR SYS - 405 can be used in different applications:

• Students already aware of theoretical quantum mechanics could validate some basic laws by experimental proofs (Bell’s inequalities…).
• Thereby a gap between theory and experiment can be bridged.
• To understand the source in practice, important optical procedures as focusing a Gaussian beam and nonlinear conversion is needed and can be experienced.

• Entangled photon pairs can be generated in environment typical in offices without need to have an optical lab including air-condition.
• Theory and methods developed by the user can be verified. (e.g. model of decoherence that is equivalent to photons can be directly validated).
• Statistical evaluations of photons
• The source can be used as a pair source for heralded photon pairs, where one photon indicates the presence of another one.
• Application as quantum imaging and QKD can be broadly investigated, where exactly one photon pair at a time is needed.

• To test the protocol stack with real measurements
• Development of particular parts of the QKD-protocol (e.g. new error-correcting codes) and combine it with the remaining part, which is already developed and well tested.
• Assistance of a FPGA based QKD-protocol stack without the use of a PC (security reasons).