Quantum Cryptography

A polarized light source for Quantum Cryptography

Quantum Cryptography

In quantum cryptography, single photons are employed to generate and transmit a key; A binary code can be assigned to individual photons. Once the key is generated, coding and encoding using the normal secret-key method can take place.

Based on the global need of secure communication, there have been significant efforts over the last decades to realize quantum cryptography schemes experimentally. For such a realization of quantum cryptography, there is a need to generate a flow of polarized single photons and the polarization direction, has to be accurately controlled. Further, for an efficient high capacity communication, i.e. a flow of a large number of individual photons per time unit, one needs a high frequency photon generation. Another crucial parameter for efficient and high-capacity communication is a low loss factor for the flow of single photons, i.e. a precise control on the level of individual photons.

Next-generation optoelectronic devices for secure communication in quantum cryptography will accordingly require:

  • A high degree of polarization
  • A high controllability level of the polarization
  • Fast switching rate
  • Efficient light extraction
  • Small-size dimensions

The pyramidal quantum dots generating linearly polarised light, with demonstrated excellent single photon statistics have the potential to fulfil the above given properties.