Ultrafast quantum key distribution using fully parallelized quantum channels

The field of quantum information processing offers secure communication protected by the laws of quantum mechanics and is on the verge of finding wider application for information transfer of sensitive data. To overcome the obstacle of inadequate cost-efficiency, extensive research is being done on the many components required for high data throughput using quantum key distribution (QKD). Aiming for an application-oriented solution, we report on the realization of a multichannel QKD system for plug-and-play high-bandwidth secure communication at telecom wavelength. For this purpose, a rack-sized multichannel superconducting nanowire single photon detector (SNSPD) system, as well as a highly parallelized time-correlated single photon counting (TCSPC) unit have been developed and linked to an FPGA-controlled QKD evaluation setup allowing for continuous operation and achieving high secret key rates using a coherent-one-way protocol.Comment: 13 pages, 6 figure

Fundamentally secure data with the help of quantum key distribution on CubeSats

With the uprise of worldwide satellite communication networks, data security is a critical issue. This issue is being addressed in the QUBE project, which proposes a CubeSat for quantum cryptography experiments. The satellite and its subsystems are currently being developed and will be used for the downlink of individual photons, or strongly attenuated light pulses, containing encoded quantum information, which can then be employed for the exchange of encryption keys. The launch of the 3U Nanosatellite is planned for early 2020. It will be built using the UNISEC-Europe standard, which has demonstrated to be able to provide a robust structure for increased reliability in CubeSat missions. In addition to state-of-the-art reaction wheels for precision pointing, the satellite will be bringing the OSIRIS optical downlink system from DLR as well as two dedicated payloads for testing components required for quantum key distribution. A sequence of numbers will be created by a miniaturized quantum random number generator (QRNG), which will be used to set the quantum states of the light pulses. These pulses will then be downlinked to the optical ground station (OGS) at DLR in Oberpfaffenhofen, Germany. The ground station is also equipped with the corresponding components for receiving individual quantum states. In addition, the random numbers will be made available via an RF downlink. The photon states received by the optical ground station will then be compared to the previously generated numbers. Due to the underlying quantum mechanics, any attempt of reading the quantum states will alter them, which makes interceptions easily detectable. These quantum key distribution experiments will evaluate whether secure communication links are possible even on a CubeSat scale. A major challenge for building the proposed CubeSat is the attitude determination and control system that will provide precise pointing. This work will outline detailed mission requirements as well as the chosen subsystems for tackling these challenges in order to achieve a successful mission and prepare for future data security

QUBE – Quantum Key Distribution with CubeSat

QUBE (Quantum Key Distribution with CubeSat) is one out of three pilot projects in the frame of the national German initiative QUTEGA to promote quantum technologies. The project is funded by the German Federal Ministry of Education and Research (BMBF) with co-funding of industry as preparation for the European flagship on Quantum Technology. With the current development pace in quantum computation, it has been predicted that in less than two decades quantum computers will be able to break encryption codes deployed today, which are currently based on mathematical problems difficult to solve with classical computation. This shows the urgent need for quantum-safe encryption that is resistant to attacks of both, quantum and classical, computers. A long term solution for quantumsafe encryption is the use of a completely random, so-called One-Time-Pad generated with true Random Number Generation (RNG) and distributed via Quantum Key Distribution (QKD). The QKD in fiber networks is limited to approx. 100 km due to damping within the carrier medium. For longer distances so far only satellite based techniques are able to transmit the keys. As a pathfinder, QUBE plans perform an in-orbit demonstration of the core technologies on a CubeSat platform

Atlantic cod (Gadus morhua) assessment approaches in the North and Baltic Sea: A comparison of environmental DNA analysis versus bottom trawl sampling

14 pages, 4 figures, 5 tables.-- This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY)The assessment of fish stocks is often dependent on scientific trawl fisheries surveys, which are both invasive and costly. The analysis of environmental DNA (eDNA) from water samples is regarded as a non-invasive and cost-effective alternative, but meaningful performance evaluations are required for a wider application. The goal of this study was to comparatively analyze a newly developed, more sensitive real-time PCR based eDNA approach with bottom trawl fisheries catches to locally detect and quantify Atlantic cod (Gadus morhua) in the North and Baltic Seas. With a species-specificity of the qPCR assay of 100%, a minimal limit of 15 Cytochrome b eDNA copies was determined for the detection of cod. In addition, a Gaussian processing regression proved a significant correlation (95%) between eDNA (copies per L of water) and cod biomass (CPUE/Ha) found by bottom trawling. The results presented here prove the potential of eDNA analyses for quantitative assessments of commercial fish stocks in the open ocean, although additional comparative analyses are needed to demonstrate its performance under different oceanographic conditionsThe information and views set out in this manuscript are based on scientific data and information collected under Service Contract “Improving cost-efficiency of fisheries research surveys and fish stocks assessments using next-generation genetic sequencing methods [EMFF/2018/015]” signed with the European Climate, Infrastructure and Environment Executive Agency (CINEA) and funded by the European UnionPeer reviewe

QUBE – Towards Quantum Key Distribution with Small Satellites

Quantum Key Distribution (QKD) in space will be integral for future quan-tum networks. The space mission QUBE will test novel integrated optics components in a three-unit CubeSat demonstrating an economic route for global-scale QKD

Influence of Material Selection on the Marginal Accuracy of CAD/CAM-Fabricated Metal- and All-Ceramic Single Crown Copings

This study evaluated the marginal accuracy of CAD/CAM-fabricated crown copings from four different materials within the same processing route. Twenty stone replicas of a metallic master die (prepared upper premolar) were scanned and divided into two groups. Group 1 (n=10) was used for a pilot test to determine the design parameters for best marginal accuracy. Group 2 (n=10) was used to fabricate 10 specimens from the following materials with one identical CAD/CAM system (GAMMA 202, Wissner GmbH, Goettingen, Germany): A = commercially pure (cp) titanium, B = cobalt-chromium alloy, C = yttria-stabilized zirconia (YSZ), and D = leucite-reinforced glass-ceramics. Copings from group 2 were evaluated for the mean marginal gap size (MeanMG) and average maximum marginal gap size (AMaxMG) with a light microscope in the “as-machined” state. The effect of the material on the marginal accuracy was analyzed by multiple pairwise comparisons (Mann–Whitney, U-test, α=0.05, adjusted by Bonferroni-Holmes method). MeanMG values were as follows: A: 46.92 ± 23.12 μm, B: 48.37 ± 29.72 μm, C: 68.25 ± 28.54 μm, and D: 58.73 ± 21.15 μm. The differences in the MeanMG values proved to be significant for groups A/C (p=0.0024), A/D (p=0.008), and B/C (p=0.0332). AMaxMG values (A: 91.54 ± 23.39 μm, B: 96.86 ± 24.19 μm, C: 120.66 ± 32.75 μm, and D: 100.22 ± 10.83 μm) revealed no significant differences. The material had a significant impact on the marginal accuracy of CAD/CAM-fabricated copings

Fabrication of Zirconia-Reinforced Lithium Silicate Ceramic Restorations Using a Complete Digital Workflow

This case report describes the fabrication of monolithic all-ceramic restorations using zirconia-reinforced lithium silicate (ZLS) ceramics. The use of powder-free intraoral scanner, generative fabrication technology of the working model, and CAD/CAM of the restorations in the dental laboratory allows a completely digitized workflow. The newly introduced ZLS ceramics offer a unique combination of fracture strength (>420 MPa), excellent optical properties, and optimum polishing characteristics, thus making them an interesting material option for monolithic restorations in the digital workflow