How Quantum Key Distribution Works (BB84 & E91)
Channel: Improbable Matter
Date: 2023-11-26

Discussion about how quantum key distribution methods based on measuring the polarization of photons can be used to keep communications secure. In particular, the methods of  Bennett and Brassard (BB84) and Ekert (E91) are explained.

Contents
00:00 - Introduction
00:25 - One-time pad
02:17 - Public key cryptography
03:22 - Photon polarization
04:46 - BB84
08:31 - No-cloning theorem
09:06 - Quantum networks
09:55 - E91
11:50 - Closing remarks

References
[1] Black Marble 2016, NASA's Goddard Space Flight Center
https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=30878
[2] IQM Quantum Computer in Espoo Finland by Ragsxl,
https://commons.wikimedia.org/wiki/File:IQM_Quantum_Computer_Espoo_Finland.jpg
[3] C. H. Bennett and G. Brassard, “Quantum cryptography: Public key distribution and coin tossing”, Proceedings of the International Conference on Computers, Systems and Signal Processing 175 (1984).
[4] C. H. Bennett and G. Brassard, “Quantum cryptography: Public key distribution and coin tossing”, Theoretical Computer Science 560, 7 (2014).
[5] S.-K. Liao et al., “Satellite-Relayed Intercontinental Quantum Network”, Physical Review Letters 120, 030501 (2018).
[6] A. K. Ekert, “Quantum Cryptography Based on Bell’s Theorem”, Physical Review Letters 67, 661 (1991).
[7] R. Ursin et al., “Entanglement-based quantum communication over 144 km”, Nature Physics 3, 481 (2007).
[8] 3D cut of the LHC dipole , CERN, OPEN-PHO-ACCEL-2014-003-8
https://home.cern/resources/image/accelerators/lhc-images-gallery
[9] NASA's Laser Communications: To the Space Station and Beyond, NASA's Goddard Space Flight Center 
https://images.nasa.gov/details/NASAs_Laser_Communications_To_the_Space_Station_and_Beyond
[10] David J. Griffiths and Darrell F. Schroeter, “Introduction to Quantum Mechanics Third Edition”, (CUP 2018). ISBN: 978-1-107-18963-8