China to Launch Quantum Communications Satellite by 2016
Last Monday, Jian-Wei Pan and a team from the University of Science and Technology of China, in Shanghai, revealed the results of an experiment in which they successfully sent single photons on a round trip to an orbiting satellite, then detected those same photons back on Earth.
The scheme proves that a satellite can beam single photons back to our planet even while it’s in orbit, a necessity for quantum communications.
Basically, Jian-Wei and his cohorts pointed a couple of telescopes at a targeted satellite, which was covered with reflectors that could bounce a laser beam back to wherever it came from on Earth. One telescope was set up to shoot pulses of light at the satellite, while the other looked for evidence of the reflection.
Each beam of light started off with 1 billion photons, and the pulse was repeated millions of times a second. On average, for every pulse of light, just one photon made the return trip back home. They reported detecting these homeward-bound photons at a rate of about 600 per second.
“These results are sufficient to set up an unconditionally secure QKD link between satellite and earth, technically,” the team wrote in their paper.
(via China Unveils Secret Quantum Communications Experiment - IEEE Spectrum)
MIT Researchers Cram 4,000 Nanoscale Optical Antennae onto a Single Silicon Chip
A single antenna—like a single ear, eye, or audio speaker—works, but combining two or more are better. This works for sending as well as receiving. By sending the same signal from two or more identical antennas in phase with each other, you can boost it, make it extremely directional, or change its shape.
This is the concept behind phased arrays, which have found great success in communications, radar, and radio astronomy. Until now, phased arrays have mostly utilized radio frequencies.
Modern nanoscale technology is now allowing researchers to create phased arrays for optical (visible) light.
Jie Sun and colleagues fabricated a phased array of 4,096 microscopic antennas on a single silicon chip. This allowed them to shape the output waveform, so they could transmit an image of the MIT logo by combining the light from each tiny antenna in precise ways—something that could not be done with (say) a similar array of LEDs. Potential applications for this research include biomedical imaging, holography, and laser communications.
(via Nanoscale antennas, etched in chip, provide precise control of light | Ars Technica)
Chinese Researchers Achieve Quantum Teleportation at Macro Scale
So by entangling two photons, for instance, physicists have demonstrated the ability to transmit quantum information from one place to another by encoding it in these quantum states—influence one of the pair and a change can be measured in the other without any information actually passing between the two. Researchers have done this before, between photons, between ions, and even between a macroscopic object and a microscopic object.
But now Chinese researchers have, for the first time, achieved quantum teleportation between two macroscopic objects across nearly 500 feet using entangled photons…
The two bundles of rubidium atoms that served as sender and receiver are more or less analogs for what we hope will someday be our “quantum Internet”—a system of routers like the ones we have now that, instead of beaming information around a vast network of fiber optic wires, will send and receive information through entangled photons.
So in a way, this is like a first proof of concept, evidence that the idea works at least in the lab. Now all we have to do is figure out is how to build several of these in series so they can actually pass information from one to the other. To do that, we only have to somehow force these quantum states to exist for longer than the hundred microseconds or so that they last now before degrading. Sounds easy enough.
Nested Coils of Light Transmit 2600 DVDs/Second Worth of Data Through the Air
A recent demonstration by Alan Willner, an engineer at the University of Southern California, moved 100 terabits (the equivalent of 2,600 DVDs) per second through the air—the fastest data transfer in free space ever. But before the tech will work commercially, engineers need to finish developing a new cable that can carry the light
(via Coiled Beams Of Light Send 100 Terabits Per Second Through The Air | Popular Science)
Quantum Photonics: Researchers Develop Technique to Transmit Data As Twisted Streams of Light
In terms of these quantum states, photons possess two distinct polarization orientations, along with a theoretically infinite number of helical wave forms, in which the photons rotate around the direction they’re moving. The latter have garnered a lot of interest, as they could potentially carry a lot more data than other optical methods.
Possible applications include quantum computing, improved fiber optic communication, point-to-point data transfer across free space, and microscopy.
Researchers have now developed a way to produce twisted light beams using silicon chips, the starting point for compact, efficient optical communication.
Xinlun Cai and colleagues shaped photons using a microscopic, ring-shaped grating, which sent twisted light out in a specified pattern. Each ring was small enough to be fabricated into integrated circuits, and capable of emitting multiple vortexes of light simultaneously. The same type of chip could also serve as a receiver for twisted light, and manipulate waves that transit through it.
(via Fabbing a chip that could encode data in a twisted vortex of light | Ars Technica)
Map of Undersea Fiber-Optic Cables
If the internet is a global phenomenon, it’s because there are fiber-optic cables underneath the ocean. Light goes in on one shore and comes out the other, making these tubes the fundamental conduit of information throughout the global village. To make the light travel enormous distances, thousands of volts of electricity are sent through the cable’s copper sleeve to power repeaters, each the size and roughly the shape of a 600-pound bluefin tuna.Once a cable reaches a coast, it enters a building known as a “landing station” that receives and transmits the flashes of light sent across the water. The fiber-optic lines then connect to key hubs, known as “Internet exchange points,” which, for the most part, follow geography and population.
Glove Translates Tactile Sign Language to Help Persons Who Are Deaf and Blind Communicate
Engineers at Germany’s Design Research Lab created the Mobile Lorm Glove to help people who are both deaf and blind communicate with other people via mobile technology.
The nodes on the glove are pressure sensors used to translate Lorm, a tactile sign language, into text or speech. The glove also does reverse translation, with vibrating motors that deliver feedback patterns according to Lorm’s method of assigning letters to different parts of the palm.
New Technique Twists Light Signals to Achieve Theoretically Limitless Bandwidth
These new, high-capacity vortex beams tap a characteristic known as orbital angular momentum (OAM).
Right now, conventional transmission protocols like Wi-Fi or LTE modulate the spin angular momentum (SAM) but not the OAM. You can think of SAM as the spin of a signal, like a bullet (or a tightly spiraling football) twisting as it carves a direct path through the air. …if SAM is the earth rotating on its axis, then OAM is its movement around the sun—not just rotation, but actual movement in space.
This new, previously untapped dimension of movement allows engineers to still manipulate SAM while layering OAM on top. Researchers from Tel Aviv University in Israel, the University of Southern California, and NASA’s Jet Propulsion Laboratory were able to twist together eight different beams of visible light using OAM resulting in 320 gigabytes per second of data transmission. That’s roughly seven Blu-ray movies per second
Computers Better at Detecting Phoniness Than Humans
A study has found that most people unwittingly smile when frustrated. What’s more, it turns out that computers programmed with the latest information from research do a better job of differentiating smiles of delight and frustration than human observers do.
Source: MIT
Read more: http://www.laboratoryequipment.com/news-Computer-Spots-Fake-Real-Smiles-052912.aspx
(via skeptv)
