Quantum Cryptography System Breaks Daylight Distance Record

An illustration of satellites orbiting earth and connected to each other by beams and arcs of various colors

Satellites can now set up quantum communications links through the air during the day instead of just at night, potentially helping a nigh-unhackable space-based quantum Internet to operate 24/7, a new study from Chinese scientists finds.

Quantum cryptography exploits the quantum properties of particles such as photons to help encrypt and decrypt messages in a theoretically unhackable way. Scientists worldwide are now endeavoring to develop satellite-based quantum communications networks for a global real-time quantum Internet.

However, prior experiments with long-distance quantum communications links through the air were mostly conducted at night because sunlight serves as a source of noise. Previously, “the maximum range for daytime free-space quantum communication was 10 kilometers,” says study co-senior author Qiang Zhang, a quantum physicist at the University of Science and Technology of China, in Shanghai.

Now researchers led by quantum physicist Jian-Wei Pan at the University of Science and Technology of China, at Hefei, have successfully established 53-kilometer quantum cryptography links during the day between two ground stations. This research suggests that such links could work between a satellite and either a ground station or another satellite, they say.

To overcome interference from sunlight, the researchers switched from the roughly 700- to 900-nanometer wavelengths of light used in all prior day-time free-space experiments to roughly 1,550 nm. The sun is about one-fifth as bright at 1,550 nm as it is at 800 nm, and 1,550-nm light can also pass through Earth’s atmosphere with virtually no interference. Moreover, this wavelength is also currently widely used in telecommunications, making it more compatible with existing networks.

Previous research was reluctant to use 1,550-nm light because of a lack of good commercial single-photon detectors capable of working at this wavelength. But the Shanghai group developed a compact single-photon detector for 1,550-nm light that could work at room temperature. Moreover, the scientists developed a receiver that needed less than one tenth of the field of view that receivers for nighttime quantum communications links usually need to work. This limited the amount of noise from stray light by a factor of several hundred.

In experiments, the scientists repeatedly established quantum communications links across Qinghai Lake, the biggest lake in China, from 3:30 p.m. to 5 p.m. local time on several sunny days, achieving transmission rates of 20 to 400 bits per second. Furthermore, they could establish these links despite roughly 48 decibels of loss in their communications channel, which is more than the roughly 40 to 45 dB of loss typically seen in communications channels between satellites and the ground and between low-Earth-orbit satellites, Zhang says. In comparison, previous daytime free-space quantum communications experiments could accommodate roughly only 20 dB of noise.

The researchers note that their experiments were performed in good weather, and that quantum communication is currently not possible in bad weather with today’s technology. Still, they note that bad weather is a problem only for ground-to-space links, and that it would not pose a problem for links between satellites.

In the future, the researchers expect to boost transmission rates and distance using better single-photon detectors, perhaps superconducting ones. They may also seek to exploit the quantum phenomenon known as entanglement to carry out more sophisticated forms of quantum cryptography, although this will require generating very bright sources of entangled photons that can operate in a narrow band of wavelengths, Zhang says.

Unhackable Quantum Networks Take to Space


The dream of a space-based, nigh-unhackable quantum Internet may now be closer to reality, thanks to new experiments with Chinese and European satellites.

Quantum physics makes possible a strange phenomenon known as entanglement. Essentially, two or more particles such as photons that get linked or “entangled” can, in theory, influence each other simultaneously no matter how far apart they are. Entanglement is essential to the workings of quantum computers, the networks that would connect them, and the most sophisticated kinds of quantum cryptography—a theoretically unhackable means of information exchange.

Back in 2012, Pan Jianwei, a quantum physicist at the University of Science and Technology of China at Hefei, and his colleagues set the distance record for quantum entanglement. A particle on one side of China’s Qinghai Lake influenced one on the other side, 101.8 kilometers away. However, entanglement gets easily disrupted by interference from the environment, and this fragility has stymied efforts at greater distance records on Earth.

Now, Pan and his colleagues have set a new record for entanglement by using a satellite to connect sites on Earth separated by up to 1,203 km. The main advantage of a space-based approach is that most of the interference that entangled photons face occurs in the 10 km or so of atmosphere closest to Earth’s surface. Above that, the photons encounter virtually no problems, the researchers say.

The researchers launched the quantum science experiment satellite (nicknamed Micius) from Jiuquan, China, in 2016. It orbits the planet at a speed of roughly 28,800 kilometers per hour and an altitude of roughly 500 km. “Through ground-based feasibility studies, we gradually developed the necessary toolbox for the quantum science satellite,” Pan says.

The experiments involved communications between Micius and three ground stations across China. Beacon lasers on both the transmitters and receivers helped them lock onto each other.

Micius generated entangled pairs of photons and then split them up, beaming the members of a pair to separate ground stations. The distance between the satellite and the ground stations varied from 500 to 2,000 km.

The record distance involved photons beamed from Micius to stations in the cities of Delingha and Lijiang. The experiments transmitted entangled photons with a 1017 greater efficiency than the best optical fibers can achieve. “We have finally sent entanglement into space and established a much, much larger quantum optics laboratory, which provides us a new platform for quantum networks as well as for probing the interaction of quantum mechanics with gravity,” Pan says.

Although these experiments generated roughly 5.9 million entangled pairs of photons every second, the researchers were able to detect only about one pair per second. Pan’s team expects a thousandfold improvement in this rate “in the next five years,” he says. He also notes that the current transmission rate for entangled pairs is close to what’s necessary to provide quantum cryptography for very brief texts; five years from now, networks of satellites and ground stations could successfully transmit at megahertz rates.

In another study, researchers in Germany found they could measure the quantum features of laser signals transmitted by a satellite a record 38,600 km away. These findings suggest that satellites could play a role in quantum networks that use less sophisticated forms of quantum cryptography that do not rely on entanglement.

Quantum physicist Christoph Marquardt from the Max Planck Institute for the Science of Light, in Erlangen, Germany, and his colleagues experimented with the Alphasat I-XL satellite, which is in geostationary orbit. Alphasat used laser signals to communicate with a ground station at the Teide Observatory in Tenerife, Spain.

Marquardt notes that the laser communications technology they experimented with is already used commercially in space. That, combined with the success of his and his colleagues’ experiments, suggests that quantum networks that do not rely on entanglement could be set up “as soon as five years from now,” he says.

Marquardt acknowledges that entanglement enables more-sophisticated strategies for foiling eavesdroppers. But “our approach only needs relatively small upgrades to proven technology,” he says.

The German scientists are now working with satellite telecommunications company Tesat-Spacecom and others to design a quantum network. Though it will be based on hardware already employed in space, it will require upgrades such as adding a quantum random number generator, Marquardt says.

Capsule Full of Space Station Junk Makes Fiery Re-Entry

A capsule filled with space station trash bit the cosmic dust Wednesday with a keenly interested scientific audience.

The cargo carrier broke apart and burned up while re-entering Earth’s atmosphere high above the Pacific. Researchers gathered information on the breakup from sensors it carried, in hopes that the data will improve future spacecraft.

Capsule Full of Space Station Junk Makes Fiery Re-Entry

Built by Virginia-based Orbital ATK Inc., the capsule had been cut loose from the International Space Station last week. It followed its own orbit until it was steered into the atmosphere, where it was consumed by the heat of re-entry.

The vessel had been the scene of another fiery experiment shortly after it left the space station. A large blaze deliberately was ignited in it so Nasa could study the spread of flames in weightlessness. Like the re-entry test, this, too, was aimed at enhancing spacecraft safety.

The so-called “Cygnus” vessel was named the S.S. Rick Husband, after the commander of the doomed space shuttle Columbia. Husband and six other astronauts were killed as Columbia broke apart during re-entry in 2003, the result of launch damage.

Nasa is paying Orbital ATK, as well as SpaceX, to stockpile the space station. SpaceX has another station supply run coming up next month, while Orbital ATK plans to resume launches from Wallops Island, Virginia, in August. Orbital ATK temporarily moved its Cygnus flights to Cape Canaveral, Florida, after its Antares rocket exploded during liftoff from Wallops Island in 2014.

This latest Cygnus was launched to the space station from Florida back in March, using another company’s rocket. Once the supplies were unloaded, the capsule was filled with more than 4,000 pounds of garbage and discarded equipment for disposal. It had delivered twice that much.

One-sixth of Brazil's microcephaly cases linked to Zika

Brasilia: Microcephaly cases in Brazil have increased to 1,271, and almost one-sixth are linked to the Zika virus.


Brazilian health ministry on Wednesday said between October 22 and April 30 out of 1,271 microcephaly cases 203 tested positive for the Zika virus.

The numbers were expected to further rise as the investigation was still ongoing, Xinhua news agency reported.

During the period, 267 babies died suspectedly from microcephaly or other abnormalities with the central nervous system during pregnancy or after labour.

The Zika virus, like dengue fever and chikungunya, is spread by the “Aedes aegypti” mosquito which is common in the Latin American and Caribbean region.

Brazil, one of the worst affected countries, registered the largest number of microphaly in newborns, supposedly related to the virus.

The Brazilian government declared a state of health emergency in November 2015.

World Health Organisation (WHO) declared a health emergency of international concern on February 1, 2016, due to the rapid spread of Zika.

Why Solar-Powered Planes Are Still a Long Way From Carrying Passengers

Swiss pilot Bertrand Piccard made headlines on Saturday when he glided a solar-powered plane onto Moffett Airfield in California after a three-day journey across the Pacific Ocean. It’s the most recent stop in an around-the-world trip that began in Abu Dhabi last spring and is intended to raise awareness about the importance of reducing carbon emissions through the use of clean energy.

The plane itself, “Solar Impulse 2,” is a true zero-fuel aircraft, powered by more than 17,000 solar cells. It’s designed to carry just one pilot – Piccard and his colleague André Borschberg have been tag-teaming the journey around the world – and has the wingspan of a jumbo jet, although it weighs only two tons.

Why Solar-Powered Planes Are Still a Long Way From Carrying Passengers

The daring trans-Pacific flight has drawn global interest to the concept of electric planes, which have existed in various forms for several decades now. Some designs rely on solar cells, while others use various types of batteries, but the overall goal is the same: to achieve flight with minimal or no fuel burning.

Electric aircraft are among the more ambitious technologies being researched around the world in an effort to reduce carbon emissions from aviation. It’s a cause that’s rapidly gaining international attention. Aviation is currently responsible for about 1 percent of all the world’s carbon emissions – and as air traffic is expected to experience rapid growth in the coming decades, that proportion could quickly climb if no steps are taken to improve the fuel efficiency of aircraft. Some estimates have suggested that by 2020, emissions from aviation could be 70 percent higher than they were in 2005.

To that end, the UN’s International Civil Aviation Organization (ICAO) proposed the world’s first carbon dioxide emissions standards for aircraft back in February. And while some environmentalists have argued that the proposal did not go far enough, the action has placed aircraft emissions on the international radar – and scientists around the world are researching ways to reduce them.

Electric flight, however, may be among the technologies that are furthest from becoming practical. So far, most of the electric planes that have achieved flight have only been able to accommodate one or two people, and it will likely be at least a decade or two before the technology will progress to the point that it’s commercially viable.

“The big challenge is the batteries,” said David Zingg, director of the University of Toronto’s Institute for Aerospace Studies. For electric planes to become competitive, their power sources need to be able to store more energy per unit mass – otherwise, their speed and weight capacities will remain impractically low.

Would You Let Companies Monitor You For Money?

In the smart home of the (not-so-distant) future, sensors will record and process occupants’ every coming and going. Opened the fridge at 3 a.m.? Noted. Washing machine hasn’t run in weeks? Your house knows. Daily habits, mealtimes, bedtime? All on file.

That’s a lot of information, and the majority of people polled in a survey released on Thursday say they’d be very worried about hackers and criminals gaining access to their (hypothetical) smart-home data.

But that doesn’t mean they’d want to keep that data to themselves. In fact, just over half of the 9,000 people surveyed worldwide said they’d share data about themselves with companies in exchange for cash.

The survey was conducted last summer by Vanson Bourne, a technology-research company, on behalf of Intel Security. In a way, its results represent the logical next step in the evolution of people’s relationship with data about themselves.

For a while now, technology users have become increasingly comfortable trading their personal data for free services. “I use Gmail for free, but I know that Google will capture some information in return,” a respondent told Pew researchers in a privacy study earlier this year. “I’m fine with that.”

If that’s the data-barter economy—give up your personal data and get convenient services in return—then we’re seeing the start of data as currency: Give up your personal data and you’ll be rewarded in actual dollars.

For many, that’s a freeing prospect. It imbues the murky data-exchange process with a new transparency, and gives consumers more agency in deciding what to offer up and what to protect.

“Privacy is really about the choice to share,” says Steve Grobman, the CTO of Intel Security. “The judgment of different individuals will vary greatly.” Indeed, smart homes will produce all kinds of data, from sensitive information about personal habits to general insights about energy use and consumer behavior. Putting dollar figures on individual data streams could help smart-home occupants decide exactly how much they value their privacy, and which elements they’re willing to give up.

But paying consumers to give up their privacy may not be particularly freeing for lower-income tech users. The practice essentially puts a premium on privacy: If you want to keep your data, and stay anonymous, you have to give up cash and deals. If this model plays out, a private smart home will be more expensive than one that reports back on its users.

Grobman says he imagines a tiered price model becoming popular. “I think that it’s reasonable to assume that some of those cost structures will be set up at higher price points, with higher degrees of anonymity and privacy protection,” he said. On the other end, lower-priced models could be subsidized “based off of access to data, as well as things like a long-term commitment.”

That’s kind of like what happened in Kansas City last year, when AT&T deployed its high-speed fiber Internet service to compete with Google Fiber. The service was priced to compete at 70 dollars a month, the same price as Google Fiber. But there was a catch: Opting out of AT&T’s “Internet Preferences” program, which recorded users’ browsing and search history, cost an extra 29 dollars a month.

Material purchases can bring happiness

With holiday shopping season in full swing, everyone’s looking for the perfect gift. For those who like to shop, there’s good news: Material things can bring happiness. In a recent study from the journal Social Psychological and Personality Science, researchers have shown that material purchases, from sweaters to skateboards, provide more frequent happiness over time, whereas experiential purchases, like a trip to the zoo, provide more intense happiness on individual occasions.

The majority of previous studies examining material and experiential purchases and happiness focused on what people anticipated about shopping or remembered about items and experiences. The University of British Columbia’s Aaron Weidman and Elizabeth Dunn wanted to know how people felt in the moment, say the first weeks with a new sweater or tablet computer. To answer this question, they assessed the real-time, momentary happiness people got from material and experiential purchases, up to five times per day for two weeks. Material purchases consisted of items such as reindeer leggings, portable speakers, or coffee makers, and examples of experiential purchases were a weekend ski trip, tickets to a hockey game, or spa gift cards.

By having people record their thoughts in the weeks following their purchases, as well as one month after their purchases, the researchers showed that material and experiential purchases bring happiness in two distinct flavors. Material purchases bring repeated doses of happiness over time in the weeks after they are bought, whereas experiential purchases offer a more intense but fleeting dose of happiness. Additionally, when people looked back on their purchases 6 weeks after Christmas, they felt more satisfaction about experiential purchases.

“The decision of whether to buy a material thing or a life experience may therefore boil down to what kind of happiness one desires,” says Mr. Weidman, “Consider a holiday shopper deciding between tickets to a concert or a new couch in the living room. The concert will provide an intense thrill for one spectacular night, but then it will end, and will no longer provide momentary happiness, aside from being a happy memory. In contrast, the new couch will never provide a thrilling moment to match the concert, but will keep the owner snug and comfortable each day throughout the winter months.”

As you go forth in your holiday shopping this season, either for yourself or others, think about what form of happiness you want, before making a purchase.