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100 1  Liang, Chuang 
245 10 Quantum cryptography for WDM networks: Encryption with 
       coherent states and key generation with fiber based 
300    219 p 
500    Source: Dissertation Abstracts International, Volume: 68-
       03, Section: B, page: 1831 
500    Adviser: Prem Kumar 
502    Thesis (Ph.D.)--Northwestern University, 2007 
520    New telecommunication techniques utilizing distinctive 
       quantum properties, e.g., measurement uncertainties and 
       entanglement, extend the capabilities of existing systems.
       Quantum cryptography, as an example, provides physical 
       layer security enforced by fundamental physical laws, 
       while modern cryptographic techniques rely on assumptions 
       of intractability of certain mathematical problems with 
       limited computational power 
520    Rapid growth of the Internet leading to global 
       telecommunications puts heavy demands on information 
       security. A novel keyed direct data encryption technique 
       based on the fundamental and irreducible quantum noise of 
       laser light is shown to be compatible with the existing 
       high-speed optical communications infrastructure. With 
       this technique, line encryption for OC-12 (622 Mbps) SONET
       data over 250 km in a wavelength-division-multiplexing 
       network is demonstrated with fully streaming data 
520    Nonlocal correlation is employed in applications including
       cryptographic key generation whose practical realizations 
       require telecom-band photon counting and entangled photon-
       pair generation. Existing telecom-band avalanche-
       photodiode based photon-counting techniques suffer from 
       large detection noise at high operation rates. New 
       techniques such as ultrashort gating and synchronous 
       sampling at the onset of avalanches are introduced for 
       suppressing the detection noise at high operation speeds. 
       Photon counting at record speeds (25 MHz) that employing 
       an avalanche photodiode is developed, demonstrated and 
       deployed in the experimental studies. Telecom-band 
       correlated photons can be directly created inside optical 
       fibers through its chi(3) nonlinearity. This technique 
       brings practical advantages such as the easy compatibility
       with fiber-optic systems, excellent spatial modal purity, 
       and potential high-speed operation. As a practical 
       development of this technique, a novel Faraday-mirror 
       based ultra-stable scheme for generating polarization 
       entangled photon-pairs is proposed and demonstrated. Fiber
       -based polarization entangled photon-pairs are 
       experimentally analyzed and characterized with various 
       single-photon detectors. In an effort to satisfy the 
       cryptographic objective of key generation, a keyed 
       protocol of entanglement-based key generation is 
       experimentally studied in wavelength-division-multiplexing
       lines wherein classical optical signals co-exist with 
       entangled photons. Telecom-band correlated photon-pair 
       generation at 9.95 GHz is also demonstrated for the first 
       time. Such high operation rate demonstrates the 
       feasibility of future high speed quantum communications 
590    School code: 0163 
590    DDC 
650  4 Engineering, Electronics and Electrical 
650  4 Physics, Optics 
690    0544 
690    0752 
710 2  Northwestern University 
773 0  |tDissertation Abstracts International|g68-03B 
856 40 |uhttp://pqdd.sinica.edu.tw/twdaoapp/servlet/