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SUMMARY:Polarization Encoded QKD in Fibre
DTSTART;VALUE=DATE-TIME:20110714T150000Z
DTEND;VALUE=DATE-TIME:20110714T170000Z
DTSTAMP;VALUE=DATE-TIME:20260711T200541Z
UID:indico-contribution-4960@events.saip.org.za
DESCRIPTION:Speakers: Sharmini Pillay (University of KwaZulu-Natal)\nQuant
 um Key Distribution employs the laws of quantum mechanics for the purpose 
 of cryptography. Two parties\, called Alice and Bob\, are able to create a
  random key which is used to encrypt a message. QKD is a provably secure m
 ethod for cryptography because any eavesdropper attempting to anonymously 
 retrieve the key must make measurements\, thereby disturbing the system. U
 sing this principle\, a high error rate between the two authenticated part
 ies indicates a compromise in the system and the process by which the key 
 is shared is aborted.\nThe quantum channel can be implemented using a free
 -space link between Alice and Bob\, but in many instances\, this is not pr
 actical for implementations. Fibre optic cables provide an alternative wit
 h current technology. In order to implement protocols such as the BB84 pro
 tocol\, the state of polarization of photons must be maintained between Al
 ice and Bob. This is because the BB84 protocol utilizes the states of pola
 rization of photons as qubits (quantum bits). However\, the polarization o
 f light is altered when passed through a fibre. This is due to impurities 
 in the fibre\, manufacturing errors or environmental stresses such as heat
 ing or movement. This causes refractive differences between polarized stat
 es which change the state of polarization. This property is called birefri
 ngence.\nPolarization mode dispersion allows for the state of polarization
  to be corrected when a photon is transmitted through fibre. If the fibre 
 is fixed\, the environmental stresses result in a unique and constant chan
 ge of polarization [4]. This can be compensated for by rotating each photo
 n appropriately before being measured and each length of fibre will requir
 e its own unique adjustment. If the fibre is subjected to variable conditi
 ons\, changes in the state of polarization of photons must be monitored an
 d adjustments must be made at suitable time intervals. Using this method\,
  polarization encoded QKD can be implemented in fibre.\n\nhttps://events.s
 aip.org.za/event/7/contributions/4960/
LOCATION: Asteria
URL:https://events.saip.org.za/event/7/contributions/4960/
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