Cryptography Reference
In-Depth Information
chapter 2
Quantum Communications
with Optical Fibers
N. Gisin, S. Iblisdir, W. Tittel, and H. Zbinden
University of Geneva
Contents
2.1 A Geneva-Biased Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.2 Time-Bin Qubits and Higher Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.3 Faint Laser Quantum Cryptography: The Plug & Play
Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.3.1 Basics of Faint Laser Quantum Key Distribution . . . . . . . . . . . . . . 23
2.3.2 A Practical Realization: The Plug & Play
Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.4 Two-Photon Quantum Cryptography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.4.1 Single-Photon Based Realizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.4.2 Entanglement-Based Realizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.4.2.1 Long-Distance Quantum Correlation . . . . . . . . . . . . . . . 29
2.4.2.2 Quantum Key Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.5 The Future of Quantum Cryptography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.5.1 Quantum Cryptography and Entanglement . . . . . . . . . . . . . . . . . . 35
2.5.2 PNS Attacks and Countermeasures . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.5.3 Three- and Four-Photon Quantum
Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.5.4 Conclusions and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Abstract
This chapter reviews experimental and theoretical achievements of the Group
of Applied Physics (GAP) at University of Geneva in the domain of quan-
tum communication. All work presented can be motivated by the goal to
render experimental quantum key distribution simple and robust, and to
