Secure communication and data protection are essential for digital security and industrial competitiveness in today’s information-technology based world. Quantum-key distribution (QKD) is cryptographic method that provides security by providing a encryption key only known to shared parties. This is possible through the concept of ‘entanglement’: a pair of entangled photons are generated by a device and sent to the encryption partners. If an eavesdropper intercepts the entangled photons intended for one party, this is detectable by the other party.