Experimental quantum communication in demanding regimes
MetadataShow full item record
Quantum communication promises to outperform its classical counterparts and enable protocols previously impossible. Specifically, quantum key distribution (QKD) allows a cryptographic key to be shared between distant parties with provable security. Much work has been performed on theoretical and experi- mental aspects of QKD, and the push is on to make it commercially viable and integrable with existing technologies. To this end I have performed simulations and experiments on QKD and other quantum protocols in regimes previously unexplored. The first experiment involves QKD via distributed entanglement through the standard telecommunications optical fibre network. I show that entanglement is preserved, even when the photons used are a shorter wavelength than the design of the optical fibre calls for. This surprising result is then used to demonstrate QKD over installed optical fibre, even with co-propagating classical traffic. Because the quantum and classical signals are sufficiently separated in wavelength, little cross-talk is observed, leading to high compatibility between this type of QKD and existing telecommunications infrastructure. Secondly, I demonstrate the key components of fully-modulated decoy-state QKD over the highest-loss channel to date, using a novel photon source based on weak coherent (laser) pulses. This system has application in a satellite uplink of QKD, which would enable worldwide secure communication. The uplink allows the complex quantum source to be kept on the ground while only simple receivers are in space, but suffers from high link loss due to atmospheric turbulence, necessitating the use of specific photon detectors and highly tailored photon pulses. My results could be applied in a near term satellite mission.
Showing items related by title, author, creator and subject.
Ouyang, Yingkai (University of Waterloo, 2013-05-01)Transmitting quantum information across quantum channels is an important task. However quantum information is delicate, and is easily corrupted. We address the task of protecting quantum information from an information ...
Topics on the information theoretic limits of quantum information processing and its implementation Raeisi, Sadegh (University of Waterloo, 2015-02-24)Recent advances in quantum technologies enabled us to make large quantum states and pushed towards examining quantum theory at the macroscopic level. However observation of quantum e ects at a macroscopic level still ...
Ried, Katja Stephanie (University of Waterloo, 2016-05-18)Quantum mechanics has achieved unparalleled success as an operational theory, describing a wide range of experiments to remarkable accuracy. However, the physical foundations on which it rests remain as puzzling as they ...