Arxiv April 13, 2018 High-orbit satellites pose a great technological challenge due to the high diffraction losses of the optical channel, and the experimental investigation of quantum channels is still lacking. Researchers in Italy report on the exchange of single photons from Global Navigation Satellite System (GNSS) at a slant distance of 20,000 kilometers, by exploiting the retroreflector array mounted on GLONASS satellites. They observed the predicted temporal spread of the reflected pulses due to the geometrical shape of array. They estimated the requirements needed for an active source on a satellite, aiming towards quantum communication from GNSS with state-of-the-art […]
Category Archives: Communications technology
Demonstration of world record: 159 Tb/s transmission over 1,045 km with 3-mode fiber
Eurekalert April 13, 2018 Researchers in Japan have developed a 3-mode optical fiber, capable of wide-band wavelength multiplexing transmission with standard outer diameter (0.125 mm) that can be cabled with existing equipment. They have demonstrated a transmission experiment over 1045 km with a data-rate of 159 Tb/s. Converting the results to the product of data-rate and distance results in 166 Pb/s×km. This is the world record in a standard outer diameter few-mode optical fiber and the largest data-rate over 1000 km for any kind of standard-diameter fiber… read more.
New device modulates light and amplifies tiny signals
Phys.org April 9, 2018 Researchers at NIST have created a plasmomechanical oscillator (PMO) that tightly couples plasmons to the mechanical vibrations of the much larger device in which it is embedded. The device consists of a gold nanoparticle, about 100 nanometers in diameter, embedded in a tiny cantilever made of silicon nitride. An air gap lies sandwiched between these components and an underlying gold plate; the width of the gap is controlled by an electrostatic actuator and bends toward the plate when a voltage is applied. The nanoparticle acts as a single plasmonic structure that has a natural frequency that […]
Thin engineered material perfectly redirects and reflects sound
Science Daily April 10, 2018 Using 3-D printers, an international team of researchers (USA – Duke University, Finland) fabricated a metamaterial made of a series of rows of hollow columns with a narrow opening cut down the middle of one side. The width of the channels between each row of columns and the size of the cavity inside each individual column controls how the sound is manipulated. The program is fed boundary conditions needed to dictate the outgoing and reflected waves’ behavior. They demonstrated redirecting a sound wave coming straight at the metamaterial to a sharp 60-degree outgoing angle with […]
Why noise can enhance sensitivity to weak signals
Phys.org April 5, 2018 To understand stochastic resonance, researchers in Japan established a simple model that excluded friction force, a parameter that they consider negligible in nano- and molecular-scale systems. They found that when a transition occurs without friction, the sensitivity of the bistable system to a Gaussian-noise-imposed weak signal becomes significantly high and the relative difference – which determines the sensitivity – of Gaussian distribution function diverges in its tail edge. This means that the sensitivity becomes anomalously high by increasing the threshold of the bistable system. The finding could pave the way for using noise rather than eliminating […]
Tuning in to magnetic ink
Eurekalert April 4, 2018 By injecting iron-based reagents into a hot acetic acid solution, researchers in Saudi Arabia synthesized magnetic iron-oxide nanoparticles that dispersed into deionized water to form an ink. When deposited as a thin film on a glass substrate, the new magnetic substrate could act as an energy-storing inductor device with an adjustable capacity of over 20 percent. By modifying the nanoparticles’ surfaces with hydrocarbon chains, they were able to produce free-standing magnetic sheets of a few millimeters in thickness. The discovery boosts prospects for inexpensive electronics that work worldwide by tuning in to multiple cellular bands and […]
Scientists create diodes made of light
Physorg March 16, 2018 Researchers in the UK created an optical version of a diode by sending lots of light into a microresonator and harnessing the circulating optical power to generate the diode effect. As the microrings can store extremely large amounts of light, even though they were sending small amounts of light into the glass rings, the circulating power was comparable to the light generated by the flood lights. They have shown that the electromagnetic field of clockwise circulating light in these glass rings effectively blocks any counterclockwise circulating light. The research opens the door to cheap and efficient […]
FCC Accuses Stealthy Startup of Launching Rogue Satellites
IEEE Spectrum March 9, 2018 According to IEEE Spectrum among the recently launched satellites, there are four satellites called SpaceBee-1, 2, 3, and 4 developed by a company in California. According to the company its network could enable satellite communications for orders of magnitude less cost than existing options. It envisages the worldwide tracking of ships and cars, new agricultural technologies, and low-cost connectivity for humanitarian efforts anywhere in the world. FCC feared that the four SpaceBees now orbiting the Earth would pose an unacceptable collision risk for other spacecraft…read more.
Study: On Twitter, false news travels faster than true stories
MIT News March 8, 2018 Researchers at MIT found that falsehood diffuses significantly farther, faster, deeper, and more broadly than the truth, in all categories of information, and in many cases by an order of magnitude. Humans, not bots, are primarily responsible for spreading misleading information therefore behavioral interventions become even more important in our fight to stop the spread of false news. The study provides a variety of ways of quantifying this phenomenon… read more. Open Access TECHNICAL ARTICLE
‘Two-way signaling’ possible with a single quantum particle
Physorg February 26, 2018 By using a quantum particle that has been put in a superposition of two different locations, researchers in Austria have theoretically shown that both partners are able to encode their messages into a single quantum particle simultaneously. Being in a quantum superposition means that the quantum particle is “simultaneously present” at each partner’s location. Therefore, both partners are able to encode their messages into a single quantum particle simultaneously, a task that is essentially impossible using classical physics. The experimental results show that the communication is secure and anonymous, the direction of communication is hidden—an eavesdropper […]