Experimental polarization encoded quantum key distribution over optical fibres with real-time continuous birefringence compensation

In this paper we demonstrate an active polarization drift compensation scheme for optical fibres employed in a quantum key distribution experiment with polarization encoded qubits. The quantum signals are wavelength multiplexed in one fibre along with two classical optical side channels that provide the control information for the polarization compensation scheme. This set-up allows us to continuously track any polarization change without the need to interrupt the key exchange. The results obtained show that fast polarization rotations of the order of 40*pi rad/s are effectively compensated for. We demonstrate that our set-up allows continuous quantum key distribution even in a fibre stressed by random polarization fluctuations. Our results pave the way for Bell-state measurements using only linear optics with parties separated by long-distance optical fibres

Polarization-stable long-distance interference of independent photons for quantum communications

Interference between fully-independent faint laser sources over two 8.5-km full polarization-controlled fiber links was performed, with stable visibility of 47.8%, an essential step towards practical implementation of quantum communication protocols

Proof-of-principle demonstration of measurement-device-independent quantum key distribution using polarization qubits

We perform a proof-of-principle demonstration of the measurement-device-independent quantum key distribution (MDI-QKD) protocol using weak coherent states and polarization-encoded qubits over two optical fiber links of 8.5 km each. Each link was independently stabilized against polarization drifts using a full-polarization control system employing two wavelength-multiplexed control channels. A linear-optics-based polarization Bell-state analyzer was built into the intermediate station, Charlie, which is connected to both Alice and Bob via the optical fiber links. Using decoy-states, a lower bound for the secret-key generation rate of 1.04x10^-6 bits/pulse is computed

Dengue Virus Type 4 Phylogenetics in Brazil 2011: Looking beyond the Veil

Dengue Fever and Dengue Hemorrhagic Fever are diseases affecting approximately 100 million people/year and are a major concern in developing countries. In the present study, the phylogenetic relationship of six strains of the first autochthonous cases of DENV-4 infection occurred in Sao Paulo State, Parana State and Rio Grande do Sul State, Brazil, 2011 were studied. Nucleotide sequences of the envelope gene were determined and compared with sequences representative of the genotypes I, II, III and Sylvatic for DEN4 retrieved from GenBank. We employed a Bayesian phylogenetic approach to reconstruct the phylogenetic relationships of Brazilian DENV-4 and we estimated evolutionary rates and dates of divergence for DENV-4 found in Brazil in 2011. All samples sequenced in this study were located in Genotype II. The studied strains are monophyletic and our data suggest that they have been evolving separately for at least 4 to 6 years. Our data suggest that the virus might have been present in the region for some time, without being noticed by Health Surveillance Services due to a low level of circulation and a higher prevalence of DENV-1 and DENV- 2

Chapter 1

Experimenting is fundamental to the training process of all scientists and engineers. While experiments have been traditionally done inside laboratories, the emergence of Information and Communication Technologies added two alter-natives accessible anytime, anywhere. These two alternatives are known as virtual and remote labs, and are sometimes indistinguishably referred as online labs. Sim-ilarly to other instructional technologies, virtual and remote labs require some ef-fort from teachers in integrating them into curricula, taking into consideration sev-eral factors that affect their adoption (i.e. cost) and their educational effectiveness (i.e. benefit). This chapter analyses these two dimensions and sustains the case where only through international cooperation it is possible to serve the large num-ber of teachers and students involved in engineering education. It presents an ex-ample in the area of Electrical and Electronics Engineering, based on a remote lab named Virtual Instruments System in Reality, and it then describes how a number of European and Latin-American institutions have been cooperating under the scope of an Erasmus+ project2, for spreading its use in Brazil and Argentina.info:eu-repo/semantics/publishedVersio