Explanipedia

Robustness of continuous variable quantum key distribution under strong polarization drift Open

Margarida Almeida, Armando N. Pinto, Nuno A. Silva · 2025

The practical deployment of Continuous Variables Quantum Key Distribution (CV-QKD) systems benefits from existing optical fiber telecommunication infrastructures. However, optical fibers introduce random variations in the state of polariza…

Probing a theoretical framework for a Photonic Extreme Learning Machine Open

Vicente Rocha, Felipe Cavalheiro Moreira, Catarina S. Monteiro, Tiago D. Ferreira, Nuno A. Silva · 2025

The development of computing paradigms alternative to von Neumann architectures has recently fueled significant progress in novel all-optical processing solutions. In this work, we investigate how the coherence properties can be exploited …

Robustness of Continuous Variable Quantum Key Distribution Under Strong Polarization Drift Open

Margarida Almeida, Armando N. Pinto, Nuno A. Silva · 2025

The practical deployment of Continuous Variables Quantum Key Distribution (CV-QKD) systems benefits from existing optical fiber telecommunication infrastructures. However, optical fibers introduce random variations in the state of polariza…

Experimental validation of a reversal operator-based QKD polarization control method Open

Sara T. Mantey, Nuno A. Silva, Armando N. Pinto, Nelson J. Muga · 2025

The ability to efficiently align the transmitter and receiver of a polarization-based Quantum Key Distribution (QKD) system at initialization and during the exchange of qubits is critical for its correct operation, otherwise resulting in a…

On the Coexistence of Quantum and Classical Signal Transmission Over Turbulent FSO Channels Open

Sara T. Mantey, Marco A. Fernandes, Gil M. Fernandes, Nuno A. Silva, Fernando P. Guiomar , et al. · 2024

Secure data transmission is essential in today's world, and quantum key distribution (QKD) is widely recognized as the technology of choice to enable information-theoretical secure symmetric key generation. While optical fibers are typical…

emancipação feminina por meio da autogestão nos movimentos de moradia Open

Nuno A. Silva, Eneida de Almeida · 2024

Este artigo trata da participação feminina no Mutirão da Associação de Construção Comunitária Paulo Freire, na Zona Leste de São Paulo, a partir de entrevistas realizadas com algumas das integrantes da Associação. Tem por objetivo abranger…

Classical channel bandwidth requirements in continuous variable quantum key distribution systems Open

Margarida Almeida, Daniel Pereira, Armando N. Pinto, Nuno A. Silva · 2024

The reconciliation method for continuous variable quantum key distribution systems is usually chosen based on its reconciliation efficiency. Nonetheless, one must also consider the requirements of each reconciliation method in terms of the…

Design and implementation of a polarization-encoding system for quantum key distribution Open

Sara T. Mantey, Nuno A. Silva, Armando N. Pinto, Nelson J. Muga · 2024

We present the design and implementation of a state-of-polarization (SOP) management technique and two efficient synchronizing methods for quantum key distribution (QKD) systems. This is achieved following a wavelength-division multiplexin…

Optical Extreme Learning Machines with Atomic Vapors Open

Nuno A. Silva, Vicente Rocha, Tiago D. Ferreira · 2024

Extreme learning machines explore nonlinear random projections to perform computing tasks on high-dimensional output spaces. Since training only occurs at the output layer, the approach has the potential to speed up the training process an…

Low-complexity conjugate homodyne detection scheme for SPAD-free DV-QKD Open

Mariana F. Ramos, Nemanja Vokić, Hannes Hübel, Armando N. Pinto, Nuno A. Silva · 2023

We demonstrate a polarization diversity conjugate homodyne detection scheme for DV-QKD, that does not require complex high computational demanding post-processing or single-photon detection. Unlike CV-QKD based on coherent detection, this …

Statistical Validation of a Physical Prime Random Number Generator Based on Quantum Noise Open

Maurício Jonas Ferreira, Nuno A. Silva, Armando N. Pinto, Nelson J. Muga · 2023

Random prime numbers are an essential resource for many asymmetric cryptographic protocols. However, despite the emerging popularity of quantum random number generators (QRNGs) as sources of secure randomness, physical prime number generat…

Impact of transmitter imbalances on the security of continuous variables quantum key distribution Open

Daniel Pereira, Margarida Almeida, Armando N. Pinto, Nuno A. Silva · 2023

Continuous-variable quantum key distribution (CV-QKD) provides a theoretical unconditionally secure solution to distribute symmetric keys among users in a communication network. However, the practical devices used to implement these system…

Reconciliation Efficiency Impact on Discrete Modulated CV-QKD Systems Key Rates Open

Margarida Almeida, Daniel Pereira, M. Facão, Armando N. Pinto, Nuno A. Silva · 2023

Continuous variable quantum key distribution (CV-QKD) allows the distribution of symmetric keys in a secure manner. CV-QKD systems can extract keys at its maximum rate when using Gaussian modulation (GM). Nonetheless, GM demands high-capac…

Polarization Diverse True Heterodyne Receiver Architecture for Continuous Variable Quantum Key Distribution Open

Daniel Pereira, Armando N. Pinto, Nuno A. Silva · 2022

We present a polarization diverse receiver architecture for continuous variables quantum key distribution. Our receiver architecture forgoes the need for any polarization matching calibrations or feedback loops and is usable in any locally…

Optimization of a Polarization-Encoding System for Practical Quantum Key Distribution Open

Hugo Costa, Nelson J. Muga, Nuno A. Silva, Armando N. Pinto · 2022

We present a method for optimizing the waveplate’s voltage range of an electro-optic based electrical polarization controller for qubit encoding in discrete-variable quantum key distribution (QKD). By increasing the number of used waveplat…

CV-QKD Security Limits Using Higher-Order Probabilistic Shaped Regular M-APSK Constellations Open

Ana Margarida Almeida, Daniel S. Pereira, Nelson J. Muga, M. Facão, Armando N. Pinto , et al. · 2022

In this work we study the performance of M-symbol (M-)Amplitude and Phase Shift Keying (APSK) constellations for Continuous-Variable Quantum Key Distribution systems. Despite the gap still observed between the performance of higher order r…

Demonstration of a Polarization-encoding Quantum Key Distribution System Open

Sara T. Mantey, Mariana F. Ramos, Nuno A. Silva, Armando N. Pinto, Nelson J. Muga · 2022

In this work, a fully functional polarization-encoding quantum key distribution system (QKD) is demonstrated. At the transmitter side, the polarization states are prepared using an algorithm to determine the voltages to be applied on the e…

Efficient Randomness Extraction in Quantum Random Number Generators Open

Maurício Jonas Ferreira, Nuno A. Silva, Nelson J. Muga · 2022

Randomness extraction algorithms play an essential role in Quantum Random Number Generators (QRNGs), where they are used to suppress unwanted classical noise and distill true randomness from their biased output. By employing the SHA-512 ha…

Impact of Shot Noise Estimation on the Secret Key Rate of a CV-QKD System Open

Daniel Pereira, Nuno A. Silva, Armando N. Pinto · 2022

In this work we present the impact of the uncertainty of the shot noise estimate on the performance of a continuous variables quantum key distribution system using a probabilistically shaped 128-APSK constellation. We demonstrate that the …

Polarization based discrete variables quantum key distribution via conjugated homodyne detection Open

Mariana F. Ramos, Armando N. Pinto, Nuno A. Silva · 2022

Optical homodyne detection is widely adopted in continuous-variable quantum key distribution for high-rate field measurement quadratures. Besides that, those detection schemes have been being implemented for single-photon statistics charac…

Polarization diverse true heterodyne receiver for continuous variable quantum key distribution Open

Daniel S. Pereira, Armando N. Pinto, Nuno A. Silva · 2022

We present a polarization diverse receiver architecture for continuous variables quantum key distribution. Our receiver architecture forgoes the need for any polarization matching calibrations or feedback loops and is usable in any locally…

Secret key rate of multi-ring M-APSK continuous variable quantum key distribution Open

Margarida Almeida, Daniel Pereira, Nelson J. Muga, M. Facão, Armando N. Pinto , et al. · 2021

Discrete modulation continuous variable quantum key distribution (DM-CV-QKD) is highly considered in real implementations to avoid the complexity of Gaussian modulation (GM), which is optimum in terms of the key rate. DM-CV-QKD systems usu…

Impact of receiver imbalances on the security of continuous variables quantum key distribution Open

Daniel Pereira, Margarida Almeida, M. Facão, Armando N. Pinto, Nuno A. Silva · 2021

Continuous-variable quantum key distribution (CV-QKD) provides a theoretical unconditionally secure solution to distribute symmetric keys among users in a communication network. However, the practical devices used to implement these system…

A Review of Self-Coherent Optical Transceivers: Fundamental Issues, Recent Advances, and Research Directions Open

Isiaka A. Alimi, Romil K. Patel, Nuno A. Silva, Chuanbowen Sun, Honglin Ji , et al. · 2021

This paper reviews recent progress on different high-speed optical short- and medium-reach transmission systems. Furthermore, a comprehensive tutorial on high-performance, low-cost, and advanced optical transceiver (TRx) paradigms is prese…

Time-interleaved quantum random number generation within a coherent classical communication channel Open

Maurício Jonas Ferreira, Daniel Pereira, Nelson J. Muga, Nuno A. Silva, Armando N. Pinto · 2021

We propose and analyse a suitable setup for a time-interleaved vacuum-based quantum random number generator (QRNG) within a classical communication channel, which removes the need for a dedicated generation device. The experimental setup w…

Reference Clock Signal Distribution for Quantum Key Distribution Open

Mariana F. Ramos, Nuno A. Silva, Nelson J. Muga, Armando N. Pinto · 2021

Quantum key distribution (QKD) requires high synchronization accuracy, specially in systems that use gated detectors at the receiver station. In this work, we present a reference clock distribution method to support long-term QKD. An avera…

Characterization of a Quantum Random Number Generator Based on Vacuum Fluctuations Open

Maurício Jonas Ferreira, Nuno A. Silva, Armando N. Pinto, Nelson J. Muga · 2021

Quantum random number generators (QRNGs) are currently in high demand across a large number of cryptographic applications as secure sources of true randomness. In this work, we characterize the conditions from which randomness can be extra…

Reversal operator to compensate polarization random drifts in quantum communications Open

Mariana F. Ramos, Nuno A. Silva, Nelson J. Muga, Armando N. Pinto · 2020

A quantum bit error rate (QBER) based algorithm for polarization random drift compensation is proposed. For a transmission window of 8 ms, for instance in aerial fiber installations, the algorithm overhead is below 1%. In an extreme turbul…

A centralized control for the operation of low voltage distribution networks with multiple Distributed Energy Resources Open

Konstantinos Kotsalos, Ismael Miranda, Nuno A. Silva, Hélder Leite · 2019

This paper proposes a secondary substation centered control approach which deals with the effective coordination of multiple Distributed Energy Resources (DER) connected along the LV grid. The presented tool manages and schedules the flexi…

Scheduling of operation in Low Voltage distribution networks with multiple Distributed Energy Resources Open

Konstantinos Kotsalos, Nuno A. Silva, Ismael Miranda, Hélder Leite · 2018

The goal of this work is to propose a tool that optimizes the operational planning of the Low Voltage (LV) grid at the day-ahead stage. The multiple Distributed Energy Resources (DER) are incorporated within a three-phase Optimal Power Flo…

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