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Quantum Key Distribution

In a society based on the continuous exchange of sensitive data and information, the importance of secure and trustable information is essential. Quantum cryptography, a branch of Quantum Communications opened a new era in the security of our information.


Exploiting Quantum Physics, it is possible to share data in an unconditionally secure way, no longer based on mathematical assumptions, but founded on the basic principles of Quantum Mechanics.

The transmitter, usually called Alice, exploiting the Quantum principles, can establish an unconditionally secure key with the receiver, commonly called Bob.

This key used with the One Time Pad encryption technique permits to encrypt and decrypt messages in an uncrackable way. Common QKD protocols use a polarization encoding scheme, where the logical bits are encoded in the polarization state of photons. In the case of optical fiber link it is preferable to use other degrees of freedom like phase or time, which are more robust in the fiber transmission.

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One of the objectives of the group is focused in increasing the performance of the optical fiber Quantum key Distribution (QKD) systems. By exploiting high-dimensional QKD protocols (space as a new degree of freedom in higher order mode (HOM) fibers and multi core fibers (MCF)), we can encode more information per photon allowing higher channel capacity and higher secret key rate.

 

Moreover the global scenario of QKD is looking forward the miniaturization of transmitters and receivers on photonic chips for a large scale distribution. In this view, we are working on the design and in the fabrication of high performance silicon photonic chips, which will be used in the real QKD applications (SPOC link).

 

Another task of the group is related to a development of a high efficient wavelength conversion for high speed single photon detection in order to increase the final performance of the QKD system. Using silicon chips it is possible to convert classical telecommunication wavelength (1310 and 1550) to a visible one, in which the actual technology related to the detectors is more efficient and with best performance.

 

Projects for Master Student and Special Courses: 

  • developing an FPGA high speed transmitter for optical fiber QKD
  • exploring the potentiality of HOM for high capacity Quantum Communications
  • design and realization of very efficient high conversion silicon chip for Quantum Cryptography
  • complete implementation of a field trial real-time QKD system (from channel layer to encryption/decryption system)
  • applied information security based on optical fiber QKD protocols