Relativistic positioning: four-dimensional numerical approach in Minkowski space-time

We simulate the satellite constellations of two Global Navigation Satellite Systems: Galileo (EU) and GPS (USA). Satellite motions are described in the Schwarzschild space-time produced by an idealized spherically symmetric non rotating Earth. The trajectories are then circumferences centered at the same point as Earth. Photon motions are described in Minkowski space-time, where there is a well known relation, Coll, Ferrando & Morales-Lladosa (2010), between the emission and inertial coordinates of any event. Here, this relation is implemented in a numerical code, which is tested and applied. The first application is a detailed numerical four-dimensional analysis of the so-called emission coordinate region and co-region. In a second application, a GPS (Galileo) satellite is considered as the receiver and its emission coordinates are given by four Galileo (GPS) satellites. The bifurcation problem (double localization) in the positioning of the receiver satellite is then pointed out and discussed in detail.Comment: 16 pages, 9 figures, published (online) in Astrophys. Space Sc

WDM weighted sum in an 8x8 SOA-based InP cross-connect for photonic deep neural networks

\u3cp\u3eWe demonstrate high fidelity weighted addition of four 10 Gb/s on-off keyed data channels on a SOA-based monolithically integrated cross-connect, with a reading error dispersion below 0.2 with respect to the target. These results open the route to feasible 8x8 one-layer neuron interconnectivity for photonic integrated deep neural networks.\u3c/p\u3

WDM weighted sum in an 8x8 SOA-based InP cross-connect for photonic deep neural networks

We demonstrate high fidelity weighted addition of four 10 Gb/s on-off keyed data channels on a SOA-based monolithically integrated cross-connect, with a reading error dispersion below 0.2 with respect to the target. These results open the route to feasible 8x8 one-layer neuron interconnectivity for photonic integrated deep neural networks

Advances in Quantum Cryptography

Quantum cryptography is arguably the fastest growing area in quantum information science.Novel theoretical protocols are designed on a regular basis, security proofs are constantly improv-ing, and experiments are gradually moving from proof-of-principle lab demonstrations to in-fieldimplementations and technological prototypes. In this review, we provide both a general introduc-tion and a state of the art description of the recent advancesin the field, both theoretically andexperimentally. We start by reviewing protocols of quantumkey distribution based on discretevariable systems. Next we consider aspects of device independence, satellite challenges, and highrate protocols based on continuous variable systems. We will then discuss the ultimate limits ofpoint-to-point private communications and how quantum repeaters and networks may overcomethese restrictions. Finally, we will discuss some aspects of quantum cryptography beyond standardquantum key distribution, including quantum data locking and quantum digital signatures

Advances in Quantum Cryptography

Quantum cryptography is arguably the fastest growing area in quantum information science. Novel theoretical protocols are designed on a regular basis, security proofs are constantly improving, and experiments are gradually moving from proof-of-principle lab demonstrations to in-field implementations and technological prototypes. In this review, we provide both a general introduction and a state of the art description of the recent advances in the field, both theoretically and experimentally. We start by reviewing protocols of quantum key distribution based on discrete variable systems. Next we consider aspects of device independence, satellite challenges, and high rate protocols based on continuous variable systems. We will then discuss the ultimate limits of point-to-point private communications and how quantum repeaters and networks may overcome these restrictions. Finally, we will discuss some aspects of quantum cryptography beyond standard quantum key distribution, including quantum data locking and quantum digital signatures