Lifeboat Foundation

Quanta of light—photons—form the basis of quantum key distribution in modern cryptographic networks. Before the huge potential of quantum technology is fully realized, however, several challenges remain. A solution to one of these has now been found.

In a paper published in the journal Science, teams led by David Novoa, Nicolas Joly and Philip Russell report a breakthrough in frequency up-conversion of single photons, based on a hollow-core photonic crystal fiber (PCF) filled with hydrogen gas. First a spatio-temporal hologram of molecular vibrations is created in the gas by stimulated Raman scattering. This hologram is then used for highly efficient, correlation-preserving frequency conversion of single photons. The system operates at a pressure-tuneable wavelength, making it potentially interesting for quantum communications, where efficient sources of indistinguishable single-photons are unavailable at wavelengths compatible with existing fiber networks.

The approach combines quantum optics, gas-based nonlinear optics, hollow-core PCF, and the physics of molecular vibrations to form an efficient tool that can operate in any spectral band from the ultraviolet to the mid-infrared—an ultra-broad working range inaccessible to existing technologies. The findings may be used to develop fiber-based tools in technologies such as quantum communications, and quantum-enhanced imaging.

Physicists from Paderborn University have developed a novel concept for generating individual photons—tiny particles of light that make up electromagnetic radiation—with tailored properties, the controlled manipulation of which is of fundamental importance for photonic quantum technologies. The findings have now been published in the journal Nature Communications.

Professor Artur Zrenner, head of the “nanostructure optoelectronics” research group, explains how tailored desired states have so far posed a challenge: “Corresponding sources are usually based on light emissions from individual semiconductor quantum emitters, which generate the photons. Here, the properties of the emitted photons are defined by the fixed properties of the quantum emitter, and can therefore not be controlled with full flexibility.”

To get around the problem, the scientists have developed an all-optical, non-linear method to tailor and control single photon emissions. Based on this concept, they demonstrate laser-guided energy tuning and polarization control of photons (i.e., the light frequency and direction of oscillation of electromagnetic waves).

A new publication in Opto-Electronic Advances overviews dynamic metasurfaces and metadevices empowered by graphene.

Metasurfaces, artificial subwavelength structured interfaces, exhibit unprecedented capabilities to manipulate electromagnetic (EM) waves ranging from visible to terahertz and microwave frequencies.

In the past decade, static metasurfaces and metadevices have been researched extensively. Due to the passive nature of building blocks in general made of metals and/or dielectrics, however, their functionalities cannot be actively tuned in situ after fabrication, which seriously impedes their application scenarios such as varifocal lens, dynamic holography, and beam steering in LiDAR. Motivated by those significant requirements, scientists have struggled for years to improve the dynamical tunability of metasurfaces, and introducing active materials or components into the passive metasurfaces has been proposed as the first thought strategy.

Breakthrough hints other cells in central nervous system, such as the brain, could be restored.

They aren’t going backward — we’re just going forward. Our orbit to the Sun makes us closer to our large adult sons.

Though Boeing may redesign the capsule’s problematic valves before a crewed flight.

With Boeing’s next Starliner crew capsule launch attempt fast approaching, the company is considering redesigning the capsule’s propulsion valves, due to issues that have so far stopped the company from launching crewed flights to the ISS and competing with SpaceX, a report from *CNBC* reveals.

Boeing is developing the Starliner spacecraft thanks to a roughly $5 billion contract it was awarded under NASA’s Commercial Crew program. The next launch attempt, called OFT-2, is scheduled for next Thursday, May 19.

Continue reading “Boeing considers redesigning problematic valve that has kept Starliner from flying NASA astronauts” »

Alpha particles are also known as alpha radiation.

Alpha particles, also known as alpha radiation, are the star players in the game of alpha decay — here’s everything you need to know.