scholarly journals LEO Satellites Constellation-to-Ground QKD Links: Greek Quantum Communication Infrastructure Paradigm

Photonics ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 544
Author(s):  
Argiris Ntanos ◽  
Nikolaos K. Lyras ◽  
Dimitris Zavitsanos ◽  
Giannis Giannoulis ◽  
Athanasios D. Panagopoulos ◽  
...  
Keyword(s):  
Quantum Communication ◽  
Satellite Communications ◽  
Global Scale ◽  
Low Earth Orbit ◽  
Atmospheric Effects ◽  
Promising Candidate ◽  
Communication Infrastructure ◽  
Decoy State ◽  
Security Applications ◽  
One Year

Quantum key distribution (QKD) has gained a lot of attention over the past few years, but the implementation of quantum security applications is still challenging to accomplish with the current technology. Towards a global-scale quantum-secured network, satellite communications seem to be a promising candidate to successfully support the quantum communication infrastructure (QCI) by delivering quantum keys to optical ground terminals. In this research, we examined the feasibility of satellite-to-ground QKD under daylight and nighttime conditions using the decoy-state BB84 QKD protocol. We evaluated its performance on a hypothetical constellation with 10 satellites in sun-synchronous Low Earth Orbit (LEO) that are assumed to communicate over a period of one year with three optical ground stations (OGSs) located in Greece. By taking into account the atmospheric effects of turbulence as well as the background solar radiance, we showed that positive normalized secure key rates (SKRs) up to 3.9×10−4 (bps/pulse) can be obtained, which implies that satellite-to-ground QKD can be feasible for various conditions, under realistic assumptions in an existing infrastructure.

scholarly journals Communications satellites in Canadian security policy: History and prospects

2021 ◽  
pp. 002070202110164
Author(s):  
Elinor Sloan
Keyword(s):  
Security Policy ◽  
Final Section ◽  
Canadian Arctic ◽  
Satellite Communications ◽  
Satellite System ◽  
Gulf War ◽  
Low Earth Orbit ◽  
Policy History ◽  
Security Environment ◽  
Communications Satellites

This article traces Canada’s early interest in space, before turning to its late 1960s decision to focus on a domestic, commercial/civilian communications satellite system in geostationary orbit and the subsequent decline in Canada’s military space efforts. It then highlights the wake-up call of the 1991 Gulf War, which demonstrated the critical importance of military communications satellites to future operations, and the steps Canada has taken to gain assured access to such satellites in the decades since. The final section outlines recent advances in low Earth orbit satellite communications (LEO satcom) and the ways in which these systems can address shortfalls in their geostationary cousins. Drawing reference to a new international security environment, it concludes that Canada should move expeditiously to incorporate LEO satcom into efforts to address the growing imperative of military satellite communications in the Canadian Arctic.

scholarly journals An approach for security evaluation and certification of a complete quantum communication system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shihan Sajeed ◽  
Poompong Chaiwongkhot ◽  
Anqi Huang ◽  
Hao Qin ◽  
Vladimir Egorov ◽  
...  
Keyword(s):  
Communication Systems ◽  
Distribution Systems ◽  
Quantum Communication ◽  
Global Scale ◽  
Security Evaluation ◽  
Wave System ◽  
System Implementation ◽  
Optical Part ◽  
Quantum Optical ◽  
Complete Quantum

AbstractAlthough quantum communication systems are being deployed on a global scale, their realistic security certification is not yet available. Here we present a security evaluation and improvement protocol for complete quantum communication systems. The protocol subdivides a system by defining seven system implementation sub-layers based on a hierarchical order of information flow; then it categorises the known system implementation imperfections by hardness of protection and practical risk. Next, an initial analysis report lists all potential loopholes in its quantum-optical part. It is followed by interactions with the system manufacturer, testing and patching most loopholes, and re-assessing their status. Our protocol has been applied on multiple commercial quantum key distribution systems to improve their security. A detailed description of our methodology is presented with the example of a subcarrier-wave system. Our protocol is a step towards future security evaluation and security certification standards.

Integrated Communications and Navigation Terminal

1991 ◽  
Vol 44 (1) ◽  
pp. 67-75
Author(s):  
M. A. Beach ◽  
P. G. Mattos ◽  
M. Chau
Keyword(s):  
Global Positioning System ◽  
Satellite Communications ◽  
Automatic Monitoring ◽  
Global Scale ◽  
Radio Communications ◽  
Communications Industry ◽  
Global Positioning ◽  
Mobile Satellite ◽  
Integrated Communications ◽  
Terminal Equipment

The mobile radio communications industry has recently witnessed a new demand for terminal equipment which can provide both communications and position reporting capabilities on a global scale–for example, the automatic monitoring of secure cargoes during international transportation. Thus, there is much interest in the development of land mobile satellite terminal equipment in the form of a single integrated unit which can economically provide both of these facilities. In this paper the development of such a unit is considered using the Inmarsat-c satellite communications service and the Navstar Global Positioning System (GPS), with extension to GLONASS possible in a receive-only version.

scholarly journals Multi-species inversion of CH<sub>4</sub>, CO and H<sub>2</sub> emissions from surface measurements

2009 ◽  
Vol 9 (14) ◽  
pp. 5281-5297 ◽  
Author(s):  
I. Pison ◽  
P. Bousquet ◽  
F. Chevallier ◽  
S. Szopa ◽  
D. Hauglustaine
Keyword(s):  
Transport Model ◽  
Regional Scale ◽  
Surface Concentration ◽  
Temporal Variations ◽  
Global Scale ◽  
Chemical Transport Model ◽  
Methyl Chloroform ◽  
Emission Fluxes ◽  
Surface Measurements ◽  
One Year

Abstract. In order to study the spatial and temporal variations of the emissions of greenhouse gases and of their precursors, we developed a data assimilation system and applied it to infer emissions of CH4, CO and H2 for one year. It is based on an atmospheric chemical transport model and on a simplified scheme for the oxidation chain of hydrocarbons, including methane, formaldehyde, carbon monoxide and molecular hydrogen together with methyl chloroform. The methodology is exposed and a first attempt at evaluating the inverted fluxes is made. Inversions of the emission fluxes of CO, CH4 and H2 and concentrations of HCHO and OH were performed for the year 2004, using surface concentration measurements of CO, CH4, H2 and CH3CCl3 as constraints. Independent data from ship and aircraft measurements and satellite retrievals are used to evaluate the results. The total emitted mass of CO is 30% higher after the inversion, due to increased fluxes by up to 35% in the Northern Hemisphere. The spatial distribution of emissions of CH4 is modified by a decrease of fluxes in boreal areas up to 60%. The comparison between mono- and multi-species inversions shows that the results are close at a global scale but may significantly differ at a regional scale because of the interactions between the various tracers during the inversion.

The Changing State of the South African Nation

2014 ◽  
pp. 1400-1418
Author(s):  
Irina Turner
Keyword(s):  
Critical Discourse Analysis ◽  
South African ◽  
Global Scale ◽  
Critical Discourse ◽  
Wide Spread ◽  
The Core ◽  
The Media ◽  
Media Reception ◽  
Countries In Transition ◽  
One Year

The colonization of discourses (Chilton & Schäffner, 2002) is a wide-spread phenomenon of globalization and naturally affects politics. The power of business-speak over politics and the media seems to be steadily increasing. Most vulnerable to that development, which the author calls businification, seem to be countries in transition that have to assert themselves rhetorically on a global scale while keeping traditional voters content at home. In an application of critical discourse analysis, the chapter seeks to trace this businification by comparing three presidential state-of-the-nation-addresses (SoNA) of three South African presidents after one year in office (1995, 2000, and 2010). Through contextualizing these texts with their media reception from a corpus of 15 newspaper articles reporting on the speeches, the outer influences on the core text become transparent. The findings suggest a parallelism between a growing professionalism in politics and the businification of political rhetoric whose development cannot be viewed as exclusively negative.

scholarly journals Proposal for space-borne quantum memories for global quantum networking

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Mustafa Gündoğan ◽  
Jasminder S. Sidhu ◽  
Victoria Henderson ◽  
Luca Mazzarella ◽  
Janik Wolters ◽  
...  
Keyword(s):  
Quantum Communication ◽  
Global Scale ◽  
Space Systems ◽  
Quantum Communications ◽  
Communication Links ◽  
Probabilistic Detection ◽  
Entanglement Distribution ◽  
Near Term ◽  
Quantum Internet ◽  
Memory Characteristics

AbstractGlobal-scale quantum communication links will form the backbone of the quantum internet. However, exponential loss in optical fibres precludes any realistic application beyond few hundred kilometres. Quantum repeaters and space-based systems offer solutions to overcome this limitation. Here, we analyse the use of quantum memory (QM)-equipped satellites for quantum communication focussing on global range repeaters and memory-assisted (MA-) QKD, where QMs help increase the key rate by synchronising otherwise probabilistic detection events. We demonstrate that satellites equipped with QMs provide three orders of magnitude faster entanglement distribution rates than existing protocols based on fibre-based repeaters or space systems without QMs. We analyse how entanglement distribution performance depends on memory characteristics, determine benchmarks to assess the performance of different tasks and propose various architectures for light-matter interfaces. Our work provides a roadmap to realise unconditionally secure quantum communications over global distances with near-term technologies.

scholarly journals Stratospheric aerosol evolution after Pinatubo simulated with a coupled size-resolved aerosol–chemistry–climate model, SOCOL-AERv1.0

2018 ◽  
Vol 11 (7) ◽  
pp. 2633-2647 ◽  
Author(s):  
Timofei Sukhodolov ◽  
Jian-Xiong Sheng ◽  
Aryeh Feinberg ◽  
Bei-Ping Luo ◽  
Thomas Peter ◽  
...  
Keyword(s):  
Climate Model ◽  
Reference Model ◽  
Volcanic Eruptions ◽  
Global Scale ◽  
Stratospheric Aerosol ◽  
Atmospheric Effects ◽  
Aerosol Layer ◽  
Aerosol Chemistry ◽  
Quasi Biennial Oscillation ◽  
Aerosol Parameters

Abstract. We evaluate how the coupled aerosol–chemistry–climate model SOCOL-AERv1.0 represents the influence of the 1991 eruption of Mt. Pinatubo on stratospheric aerosol properties and atmospheric state. The aerosol module is coupled to the radiative and chemical modules and includes comprehensive sulfur chemistry and microphysics, in which the particle size distribution is represented by 40 size bins with radii spanning from 0.39 nm to 3.2 µm. SOCOL-AER simulations are compared with satellite and in situ measurements of aerosol parameters, temperature reanalyses, and ozone observations. In addition to the reference model configuration, we performed series of sensitivity experiments looking at different processes affecting the aerosol layer. An accurate sedimentation scheme is found to be essential to prevent particles from diffusing too rapidly to high and low altitudes. The aerosol radiative feedback and the use of a nudged quasi-biennial oscillation help to keep aerosol in the tropics and significantly affect the evolution of the stratospheric aerosol burden, which improves the agreement with observed aerosol mass distributions. The inclusion of van der Waals forces in the particle coagulation scheme suggests improvements in particle effective radius, although other parameters (such as aerosol longevity) deteriorate. Modification of the Pinatubo sulfur emission rate also improves some aerosol parameters, while it worsens others compared to observations. Observations themselves are highly uncertain and render it difficult to conclusively judge the necessity of further model reconfiguration. The model revealed problems in reproducing aerosol sizes above 25 km and also in capturing certain features of the ozone response. Besides this, our results show that SOCOL-AER is capable of predicting the most important global-scale atmospheric effects following volcanic eruptions, which is also a prerequisite for an improved understanding of solar geoengineering effects from sulfur injections to the stratosphere.

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