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AIT’s Optical Quantum Technologies experts develop worldwide unique quantum key distribution systems based on entangled photons (light particles). The secure distribution of electronic keys is an essential prerequisite for secure electronic communication between two parties.

The seminal research carried out in this field by Prof. Anton Zeilinger at the University of Vienna provided the basis for the EU project SECOQC. The principle developed within this project, which prevents eavesdropping by securely exchanging a digital key between two parties, was successfully verified in 2008. The AIT quantum key distribution system AIT QKD EPR-SYS-405 (Einstein-Podolski-Rosen Entanglement Photon Pair System EPR SYS-405) is now available as a standard prototype for research and development.

The EPR SYS-405 is AIT's modular platform for quantum mechanics experiments for universities, research centres, and industry. The entire system is built around an electronically stabilized source of entangled photons at 810nm which enables long term operation with high generation rates. The number and quality of the generated photon pairs strongly depends on the pump laser diode used, which can be selected from a number of options. With a stabilized narrow-bandwidth laser diode, a measured coincidence rate of C = 500/(s*mW) at an overall visibility of V>98% can be achieved.

From the source, the photons are transmitted via either free space links (optical telescopes) or via optical fibre to one or two BB84 modules. The free space link sender and receiver telescopes include electronic support for alignment and calibration.

In the BB84 detector modules the photons are continuously analyzed in the {0, 90} and {+45, -45} bases and time-tagged with maximum precision. The matching of the corresponding detection events, as well as the classical post-processing (sifting, error correction, privacy amplification) is performed on commercial off-the-shelf laptops. AIT offers the entire QKD stack software together with its source code (under GPL) and, as such, provides an easy way to develop and test new approaches and protocols in QKD post-processing.

AIT provides different options for training in operating and carrying out experiments with the EPR SYS-405. All customers may access a web-based bulletin board and bug-tracking system to resolve software issues. Furthermore, AIT provides training at its facilities in Vienna, or on site in the laboratory of the customer.

The EPR SYS-405 can be configured exactly to your needs by selecting two or more options relating to the following modular building blocks:

  • Pump laser diode
  • Nonlinear crystal
  • Stabilization
  • Fibre coupling or free space optical telescopes
  • Detectors
  • Electronics
  • Post-processing PCs
  • Software
  • Training

Technical specifications

  • Implementation of BBM92 protocol
  • AIT QKD protocol stack
  • Wavelength 810 nm
  • Reach in single mode optical fibres up to 5 km
  • Transmission range without optical fibre with telescope in the dark approx. 0 - 500 m
  • Operating temperature in the  10-40 ° C range
  • Guaranteed key rate at distance of 0 m at least 1kbit/s
  • Generated raw key rate at a distance of 5 km at least 0.2 kbit/s