Category Archives: Quantum Physics

June 22, 2017 Artist's rendering of a quantum thermometer. Credit: Emily Edwards/JQI

In an arranged marriage of optics and mechanics, physicists have created microscopic structural beams that have a variety of powerful uses when light strikes them. Able to operate in ordinary, room-temperature environments, yet exploiting some of the deepest principles of quantum physics, these optomechanical systems can act as inherently accurate thermometers, or conversely, as a type of optical shield that diverts heat. The research was performed by a team led by the Joint Quantum Institute (JQI), a research collaboration of the National Institute of Standards and Technology (NIST) and the University of Maryland.

Described in a pair of new papers in Science and Physical Review Letters, the potential applications include chip-based temperature sensors for electronics and biology that would never need to be adjusted since they rely on fundamental constants of nature; tiny refrigerators that can cool state-of-the-art microscope components for higher-quality images; and improved "metamaterials" that could allow researchers to manipulate light and sound in new ways.

Made of silicon nitride, a widely used material in the electronics and photonics industries, the beams are about 20 microns (20 millionths of a meter) in length. They are transparent, with a row of holes drilled through them to enhance their optical and mechanical properties.

"You can send light down this beam because it's a transparent material. You can also send sound waves down the beam," explained Tom Purdy, a NIST physicist who is an author on both papers. The researchers believe the beams could lead to better thermometers, which are now ubiquitous in our devices, including cell phones.

"Essentially we're carrying a bunch of thermometers around with us all the time," said JQI Fellow Jake Taylor, senior author of the new papers. "Some provide temperature readings, and others let you know if your chip is too hot or your battery is too cold. Thermometers also play a crucial role in transportation systemsairplanes, carsand tell you if your engine oil is overheating."

But the problem is that these thermometers are not accurate off the shelf. They need to be calibrated, or adjusted, to some standard. The design of the silicon nitride beam avoids this situation by relying on fundamental physics. To use the beam as a thermometer, researchers must be able to measure the tiniest possible vibrations in the beam. The amount that the beam vibrates is proportional to the temperature of its surroundings.

The vibrations can come from two kinds of sources. The first are ordinary "thermal" sources such as gas molecules buffeting the beam or sound waves passing through it. The second source of vibration comes purely from the world of quantum mechanics, the theory that governs behavior of matter at the atomic scale. The quantum behavior occurs when the researchers send particles of light, or photons, down the beam. Struck by light, the mechanical beam reflects the photons, and recoils in the process, creating small vibrations in the beam. Sometimes these quantum-based effects are described using the Heisenberg uncertainty relationshipthe photon bounce leads to information about the beam's position, but because it imparts vibrations to the beam, it adds uncertainty to the beam's velocity.

"The quantum mechanical fluctuations give us a reference point because essentially, you can't make the system move less than that," Taylor said. By plugging in values of Boltzmann's constant and Planck's constant, the researchers can calculate the temperature. And given that reference point, when the researchers measure more motion in the beam, such as from thermal sources, they can accurately extrapolate the temperature of the environment.

However, the quantum fluctuations are a million times fainter than the thermal vibrations; detecting them is like hearing a pin drop in the middle of a shower.

In their experiments, the researchers used a state-of-the-art silicon nitride beam built by Karen Grutter and Kartik Srinivasan at NIST's Center for Nanoscale Science and Technology. By shining high-quality photons at the beam and analyzing photons emitted from the beam shortly thereafter, "we see a little bit of the quantum vibrational motion picked up in the output of light," Purdy explained. Their measurement approach is sensitive enough to see these quantum effects all the way up to room temperature for the first time, and is published in this week's issue of Science.

Although the experimental thermometers are in a proof-of-concept phase, the researchers envision they could be particularly valuable in electronic devices, as on-chip thermometers that never need calibration, and in biology.

"Biological processes, in general, are very sensitive to temperature, as anyone who has a sick child knows. The difference between 37 and 39 degrees Celsius is pretty large," Taylor said. He foresees applications in biotechnology, when you want to measure temperature changes in "as small an amount of product as possible," he said.

The researchers go in the opposite direction in a second proposed application for the beams, described in a theoretical paper published in Physical Review Letters.

Instead of letting heat hit the beam and allow it to serve as a temperature probe, the researchers propose using the beam to divert the heat from, for example, a sensitive part of an electromechanical device.

In their proposed setup, the researchers enclose the beam in a cavity, a pair of mirrors that bounce light back and forth. They use light to control the vibrations of the beam so that the beam cannot re-radiate incoming heat in its usual direction, towards a colder object.

For this application, Taylor likens the behavior of the beam to a tuning fork. When you hold a tuning fork and strike it, it radiates pure sound tones instead of allowing that motion to turn into heat, which travels down the fork and into your hand.

"A tuning fork rings for a long time, even in air," he said. The two prongs of the fork vibrate in opposite directions, he explained, and cancel out a way for energy to leave the bottom of the fork through your hand.

The researchers even imagine using an optically controlled silicon nitride beam as the tip of an atomic force microscope (AFM), which detects forces on surfaces to build up atom-scale images. An optically controlled AFM tip would stay cooland perform better. "You're removing thermal motion, which makes it easier to see signals," Taylor explained.

This technique also could be put to use to make better metamaterials, complex composite objects that manipulate light or sound in new ways and could be used to make better lenses or even so-called "invisibility cloaks" that cause certain wavelengths of light to pass through an object rather than bouncing from it.

"Metamaterials are our answer to, 'How do we make materials that capture the best properties for light and sound, or for heat and motion?'" Taylor said. "It's a technique that has been widely used in engineering, but combining the light and sound together remains still a bit open on how far we can go with it, and this provides a new tool for exploring that space."

Explore further: Fundamentally accurate quantum thermometer created

More information: "Quantum correlations from a room-temperature optomechanical cavity" Science (2017). science.sciencemag.org/cgi/doi/10.1126/science.aag1407

Xunnong Xu et al. Cooling a Harmonic Oscillator by Optomechanical Modification of Its Bath, Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.118.223602

Better thermometers might be possible as a result of a discovery at the National Institute of Standards and Technology (NIST), where physicists have found a way to calibrate temperature measurements by monitoring the tiny ...

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For the first time, researchers at the California Institute of Technology (Caltech), in collaboration with a team from the University of Vienna, have managed to cool a miniature mechanical object to its lowest possible energy ...

Elemental metals usually form simple, close-packed crystalline structures. Though lithium (Li) is considered a typical simple metal, its crystal structure at ambient pressure and low temperature remains unknown.

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Quantum thermometer or optical refrigerator? - Phys.org - Phys.Org

Big data is a challenge for all automakers, but especially German companies because they target affluent customers who want the latest technology.

At the same time, the focus on computing pits the automakers against Silicon Valley tech companies with far more experience in the field, and creates an opening for firms like Apple and Google, which are already encroaching on the car business.

Google has long been working on self-driving or autonomous cars, and Tim Cook, the chief executive of Apple, said this month that the company best known for making iPhones is focusing on autonomous systems for cars and other applications.

That has put pressure on automakers. German companies in particular have already made investments in ride-sharing services, in part to combat the rise of Uber, and are now looking further into the future.

Efforts by Volkswagen, trying to remake itself as a technology leader as it recovers from an emissions scandal, show how far into exotic realms of technology carmakers are willing to go.

Volkswagen, a German company, recently joined the handful of large corporations worldwide that are customers of D-Wave Systems, a Canadian maker of computers that apply the mind-bending principles of quantum physics.

While some experts question their usefulness, D-Wave computers housed in tall, matte black cases that recall the obelisks in the science fiction classic 2001: A Space Odyssey can in theory process massive amounts of information at unheard-of speeds. Martin Hofmann, Volkswagens chief information officer, is a believer.

For us, its a new era of technology, Mr. Hofmann said in an interview at Volkswagens vast factory complex in Wolfsburg, Germany.

First theorized in the 1980s, quantum computers seek to harness the strange and counterintuitive world of quantum physics, which studies the behavior of particles at the atomic and subatomic level. While classical computers are based on bits with a value of either 1 or 0, the qubits in a quantum computer can exist in multiple states at the same time. That allows them, in theory, to perform calculations that would be beyond the powers of a typical computer.

This year Volkswagen used a D-Wave computer to demonstrate how it could steer the movements of 10,000 taxis in Beijing at once, optimizing their routes and thereby reducing congestion.

Because traffic patterns morph constantly, the challenge is to gather and analyze vehicle flows quickly enough for the data to be useful. The D-Wave computer was able to process in a few seconds information that would take a conventional supercomputer 30 minutes, said Florian Neukart, a scientist at a Volkswagen lab in San Francisco.

Such claims are met with skepticism by some experts, who say there is no convincing proof that D-Wave computers are faster than a well-programmed conventional supercomputer. And unlike a quantum computer, a supercomputer does not have components that must be kept at temperatures colder than deep space.

If this were an application where D-Wave were actually faster, then it would be the first time wed ever seen that, said Scott Aaronson, a vocal D-Wave skeptic who is a professor of theoretical computer science at the University of Texas at Austin.

It would be particularly astonishing that this milestone should happen first for a Volkswagen application problem, Mr. Aaronson said in an email.

Volkswagen executives say they will publish the results of their work with D-Wave computers, allowing outsiders to try to debunk them.

If the D-Wave collaboration proves to be a misstep for Volkswagen, it would illustrate the hazards of big data for companies whose main focus for the past century has been the internal combustion engine. It also reflects the stakes for one of the worlds biggest carmakers.

Suppliers are also gearing up for an era of automotive big data. Bosch, the electronics maker based in a suburb of Stuttgart, said Monday that it would invest 1 billion euros, or $1.1 billion, to build a new factory in Dresden to produce chips for a variety of applications, including the sensors used in self-driving cars.

Bosch prefers to build its own chips rather than buy them from a supplier, said Christine Haas, director for connected services at the company. When you have done it yourself, then you have a much deeper understanding of the technology, she said.

Some car companies have decided to concentrate on what they do best and let others handle the computing.

Volvo Cars has been a pioneer in marrying digital technology and automobiles. It has turned to outside providers like Ericsson, a Swedish maker of telecommunications equipment, for computer technology. In May, Volvo said it would install Googles Android operating system in new cars beginning in 2019. And the company is cooperating with Uber to develop self-driving cars.

We are trying to embrace it, said Martin Kristensson, senior director for autonomous driving and connectivity strategy at Volvo, of the challenge from Silicon Valley.

But, like Volkswagen, many are trying to develop capabilities in-house. Mr. Stolle of BMW said that the carmaker which hired more information technology specialists last year than mechanical engineers needs huge data-crunching capability.

The company has a fleet of 40 prototype autonomous cars it is testing in cooperation with Intel, a chip maker; Mobileye, an Israeli self-driving technology company; and Delphi, an auto components supplier.

BMW uses artificial intelligence to analyze the enormous amounts of data compiled from test drives, part of a quest to build cars that can learn from experience and eventually drive themselves without human intervention.

After test sessions, hard disks in the cars are physically removed and connected to racks of computers at BMWs research center near Munich. The data collected would fill the equivalent of a stack of DVDs 60 miles high, Mr. Stolle said.

That is much more than could be efficiently transmitted over the internet to remote data storage facilities operated by outside providers in the cloud.

A large part of the data center has to be on premises, Mr. Stolle said. The amount is so huge it doesnt work in the cloud.

Follow Jack Ewing on Twitter @JackEwingNYT.

A version of this article appears in print on June 23, 2017, on Page B4 of the New York edition with the headline: Europes Car Giants Race to Outsmart Apple and Google.

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BMW and Volkswagen Try to Beat Apple and Google at Their Own Game - New York Times

June 21, 2017• Physics 10, 68

A team of experimentalists and theorists proposes a scalable protocol for quantum computation based on topological superconductors.

Adapted from T. Karzig et al., Phys. Rev. B (2017)

The Herculean thrust to realize a quantum computer by many research groups around the world is, in my opinion, one of the most exciting endeavors in physics in quite some time. Notwithstanding the potential applications that have motivated many companies in this endeavor, a quantum computer represents the most promising avenue to peer into quantum phenomena on a macroscopic scale. As with any such great effort, the race to build a quantum computer has many competitors pursuing a variety of approaches, some of which appear to be on the verge of creating a small machine [1]. However, such small machines are unlikely to uncover truly macroscopic quantum phenomena, which have no classical analogs. This will likely require a scalable approach to quantum computation. A new study by Torsten Karzig from Microsoft Station Q, California, and colleagues [2] brings together the expertise of a large and diverse group of physicists, ranging from experimentalists to topologists, to lay out a roadmap for a scalable architecture based on one of the most popular approaches.

Karzig and colleagues paper represents a vision for the future of a sequence of developments that started with the seminal ideas of topological quantum computation (TQC) as envisioned by Alexei Kitaev [3] and Michael Freedman [4] in the early 2000s. The central idea of TQC is to encode qubits into states of topological phases of matter (see Collection on Topological Phases). Qubits encoded in such states are expected to be topologically protected, or robust, against the prying eyes of the environment, which are believed to be the bane of conventional quantum computation. This is because states of topological phases are locally indistinguishable from each other, so that qubits encoded in such states can evade the destructive coupling to the environment. But experimentally accessible topological phases of matter with the requisite properties for TQC, such as the ability to host quasiparticles known as Majorana zero modes, have been elusive. A milestone in this direction was reached in 2010, when researchers realized [57] that the combination of rather conventional ingredients, such as special semiconductors, superconductors, and magnetic fields, could result in one such phasea topological superconductor. This realization motivated experimentalists to discover signatures of this topological phase just a few years after its prediction [8]. However, the topological superconductors, or Majorana nanowires as they are often called, made in these first experiments were plagued by device imperfections such as impurities [8]. While topological robustness is supposed to protect devices from small imperfections, it is sometimes overlooked that the strength of such imperfections must be below a pretty low threshold for topological robustness to be operative.

A new wave of optimism swept the search for TQC-ready topological superconductors in 2016. Thats when experimental groups from the University of Copenhagen and from the Delft University of Technology, led by Charlie Marcus and Leo Kouwenhoven, respectively, demonstrated high-quality Majorana nanowires that were likely to be in the topological regime [9, 10]. These devices, fabricated through epitaxial growth of superconducting aluminum on indium antimonide semiconductors, showed evidence of a high-quality superconducting gap [10] and also of near energy degeneracy between the topological qubit states [9]; a large energy difference between qubit states is often related to the detrimental decoherence rate of a qubit. However, the rules of the game of designing and fabricating Majorana nanowire devices have proven to be rather different from what had been anticipated. For example, it turns out that it is quite straightforward to drive the newly fabricated devices [9] into the desirable Coulomb blockade regime (where the quantization of electronic charge dominates charge transport) but difficult to fabricate controllable contacts to connect the devices to superconducting circuitry. Interestingly, concurrent theoretical work has clarified that the topological qubit state of a Majorana nanowire can be measured via the phase shift of electron transport through the device when the transport is in the Coulomb blockade regime. This work led to suggestions that the basic operations for TQC could be performed using a procedure that relied on measurements of topological qubits.

Karzig and colleagues study comes at a point in time where there is optimism for the realization of TQC using Majorana nanowires but possibly along a path with several constraints. For example, branched structures of a nanowire could be used to generate a network of wires for TQC, but superconducting contacts are only easy to make at the ends of the wire. This would mean that superconducting contacts must be avoided in making a large network of wires. Also, the qubit lifetime will ultimately likely be limited by quasiparticle poisoning, a phenomenon in which an anomalously large number of unwanted quasiparticles, arising from Cooper electron pairs broken by stray microwaves, exists in the devices. The Karzig study brings together a large number of authors with expertise in device fabrication, in strategies for TQC, and in the solid-state-physics issues involving Majorana nanowires. The researchers propose a protocol for scalable TQC based on the existing Majorana nanowires, assuming that they can be brought into the topological phase.

The protocol involves designing a network from small sets of Majorana wires and performing a sequence of measurements on the sets (Fig. 1). The central idea is to use physical constraints on the network, such as aligning all wires with a global magnetic field, to predict which sets may be measured easily to perform TQC. For example, the researchers considered networks made from sets of four and six wires (tetron and hexon designs) together with the rule that only nearby Majorana zero modes could be measured in each configuration. They then devised a strategy for TQC that optimizes robustness to quantities such as environmental temperature and noise as well the size of the network. The result of the analysis is a few scalable architectures that future experimental groups could pick between, depending on their device-construction capabilities and computational goals. The hexon architectures are likely to be computationally more efficient than the tetron architectures but will probably be more difficult to construct.

While the scope of this work might be limited to these specific devices, detailed analysis of this kind is absolutely key to motivating both experimentalists and theorists to make progress towards a realistic platform for TQC that actually works in practice. The Karzig study likely lays the foundation for analogous work with other topological platforms as they become experimentally viable candidates for TQC. I must also clarify that the significance of this work does depend on whether future experiments meet the outstanding experimental challenges, foremost among which is the reliable generation of Majorana nanowires in a topological phase. That being said, I think Karzig and co-workers paper will serve as a case study to follow, even if the properties of topological superconducting systems turn out to be somewhat different from the ones assumed.

This research is published in Physical Review B.

Jay Sau is an Assistant Professor of Physics at the University of Maryland (UMD), College Park. He holds a B.Tech. in electrical engineering from the Indian Institute of Technology (IIT) in Kanpur, India, and a Ph.D. in physics from the University of California at Berkeley. After postdoctoral positions at UMD and Harvard University, he joined the Physics Department at UMD in 2013. His research group develops theoretical tools in condensed-matter physics to predict and understand topological phases that might one day be used to perform topological quantum computation.

Torsten Karzig, Christina Knapp, Roman M. Lutchyn, Parsa Bonderson, Matthew B. Hastings, Chetan Nayak, Jason Alicea, Karsten Flensberg, Stephan Plugge, Yuval Oreg, Charles M. Marcus, and Michael H. Freedman

Phys. Rev. B 95, 235305 (2017)

Published June 21, 2017

Torsten Karzig, Christina Knapp, Roman M. Lutchyn, Parsa Bonderson, Matthew B. Hastings, Chetan Nayak, Jason Alicea, Karsten Flensberg, Stephan Plugge, Yuval Oreg, Charles M. Marcus, and Michael H. Freedman

Phys. Rev. B 95, 235305 (2017)

Published June 21, 2017

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Viewpoint: A Roadmap for a Scalable Topological Quantum Computer - Physics

Schrdingers Cat

Even if youre not that into heavy science, youre probably familiar with Schrdingers cat, the thought experiment that allows us to consider quantum states in which more than one state is possible at once. The cat is in a box that is closed, and with it is a vial of poison, a hammer that can smash the vial, a geiger counter, and a trace amount of radioactive material. The radioactive material, however, is such asmall amount that the geiger counter has only a 50 percent chance of detecting it. If it does, it will trigger the hammers smashing of the vial, and the cat will die.

We wont know until we open the box if the cat is alive or dead. We just know that each possibility it getting killed or surviving is equally likely. So, until the box is open, the cat exists in a kind of super position both alive and dead. Schrdingers point was that demonstrating its impossibility and silliness. But thanks to quantum physics, we now knowits not that silly and not necessarily impossible.

Speaking of thought experiments used to talk about quantum physics that were devised by people who never even considered quantum physics, lets consider the Zeno effect and the anti-Zeno effect. Zeno of Elea was a philosopher who made it his life mission to prove that everything was B.S., and he did that by devising paradoxes to demonstrate that even things that seem obviously true to us are, in fact, false. One of these is the arrow paradox, from which arises the Zeno effect and its corollary.

The Zeno effect works like this: in order to measure or observe something at aparticular moment,it must be motionless. Say you want to see if an atom has decayed or not. In reality, although there are two possible states, most of the time the chances are not 50/50. Thats because it takes time for something to decay at least a tiny bit of time. Therefore, if you check on the atom quickly and often enough, it wont decay.The corollary anti-Zeno effect is also true. If you delay measurement until the atom is likely to have decayed, then keep this pattern going, you can force the system to decay more rapidly.

Scientists at Washington University in St. Louis wanted to know what happens if you disturb the system again and again, but dont relay any data. In other words, they wanted to see if it is the act of measurement and observation or simply the disturbing influence that causes the Zeno effect. To find out, they experimented with qubits and devised quasimeasurement,in which the atom is disturbed, but no information about it is measured or relayed.

The team found that even quasimeasurements cause the Zeno effect. The quantum environment doesnt need to be connected to the outside environment for the disturbance to achieve the effect. These findingsare interesting because they open up new areas of research into how we might beable to control quantum systems.

Oh, and by the way: no cats, philosophers, or physicists were hurt in the experiments.

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How Schrdinger's Cat Helps Explain the New Findings About the Quantum Zeno Effect - Futurism

In Brief Chinese physicists managed to demonstrate long-distance quantum entanglement in space, breaking previous records. This development, made possible by a novel method, could lead to improved information storage and transfer in the future. Spooky Action Gets to Space

When it comes to weird science stuff, quantum entanglement is probably nearthe top of the list, especially back in the days when Einstein referred to it as that spooky action at a distance. Physicists have since demonstrated the spookyphenomenon to be possible, but now theywant to extend itsreach. A new study shows its possible for quantum entanglement to spanfar longer distances than previously demonstrated.

We have demonstrated the distribution of two entangled photons from a satellite to two ground stations that are 1,203 kilometers [748 miles] apart, lead author Juan Yin, physicist at the Science and Technology University of China in Shanghai, explained in aresearch paper published in the journal Science. The previous record for entanglement distribution reached only 100 kilometers (62 miles).

Yins team used the Micius, the worlds first quantum-enabled satellite which China launched in 2016, to transmit entangled photons to several ground stations separated by long distances. They managed to achieve this feat by using laser beams to prevent the light particles from gettinglost as they traveled.

The result again confirms the nonlocal feature of entanglement and excludes the models of reality that rest on the notions of locality and realism, Yin and his colleagues wrote.

Though quantum entanglement is incredibly complex, its possible to explain itin simple terms. Two or more particles are entangled or linked when a change in ones state or properties instantaneously affects the others. What makes this stranger is that this link works regardless of distance. This phenomenon becomes particularly useful in storing information as in the case of using quantum bits (qubits) in quantum computing.

By proving that quantum entanglement can be maintained in space over such a long distance, this work paves the way for long-distance satellite quantum communication and maybe even realize the possibilities for quantum teleportation. Long-distance entanglement distribution is essential for the testing of quantum physics and quantum networks, Yins team wrote.

Advances in quantum cryptography, which rely heavily on extending entanglement, could change the way information is stored and transferred in the future opening up applications in improved security in communication and even payment systems.

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Physicists Demonstrate Record Breaking Long-Distance Quantum Entanglement in Space - Futurism

China has used a laser on a satellite orbiting 480 kilometres above the earth to produce entangled photons and beam them to stations on the ground. Picture: Cai Yang/Xinhua via ZUMA

IN A bid to build an entirely new kind of internet completely secure and impervious to hackers China has pulled off a major feat in particle physics.

Chinese scientists have set a new distance record for beaming a pair of entangled particles: photons of light that behave like twins and experience the exact same things simultaneously, even though theyre separated by great distances.

The principle is called quantum entanglement and its one of the subatomic worlds weirdest phenomena. And China has smashed the distance record for quantum entanglement.

In a groundbreaking experiment led by Professor Jian-Wei Pan of Hefei University in China, a laser on a satellite orbiting 480 kilometres above the earth produced entangled photons.

They were then transmitted to two different ground-based stations 1200 kilometres apart, without breaking the link between the photons, the researchers said in a report published in the journal Science.

That distance achieved in the experiment is 10 times greater than the previous record for entanglement and is also the first time entangled photons have been generated in space.

Its a huge, major achievement, Thomas Jennewein, physicist at the University of Waterloo in Canada, told Science. They started with this bold idea and managed to do it.

China launched its first quantum satellite in August and if all goes according to plan will send up plenty more to create a system of communication which relies on entanglement.

A COMPLETELY NEW INTERNET

By launching a group of quantum-enabled satellites, China hopes to create a super secure network that uses an encryption technique based on the principles of a field known as quantum communication.

In physics we are trying, and we have demonstrated some encryption techniques that rely on the law of physics rather than the mathematical complexity and we call this quantum key distribution, professor Ping Koy Lam from the ANUs Department of Quantum Science told news.com.au last year, before China launched its first quantum satellite.

For that to work you need to send laser beams that carry certain information, quantum information, and then you need the senders and the receivers to get together to find a protocol to secure the communication.

The reason it cant be hacked is because the information carried in the quantum state of a particle cannot be measured or cloned without destroying the information itself.

We can show that this kind of quantum encryption works in a city radius or at most between two nearby cities, Prof Lam said.

However China believes the atmosphere in space will allow the photons to travel further without disruption because in space theres nothing to attenuate light.

In the latest experiment, both stations which received the photons were in the mountains of Tibet, at a height that reduced the amount of air the fragile photons had to traverse.

The successful characterisation of quantum features under such conditions is a precondition for a global quantum communication network using satellites that would link metropolitan area quantum networks on the ground. Picture: Google, ESASource:Supplied

A NEW SPACE RACE

Chinas ongoing progress will no doubt be watched closely by security agencies around the world.

While the spectre of a communication network enabled via quantum satellites is still a long way off, as China edges closer to the goal it has led to predictions of a new space race.

Quantum technology has been a major focus of Chinas five-year economic development plan, released in March 2016. While other space agencies have been experimenting with the technology, none have seen the level of financial support provided by Beijing.

China has not disclosed how much money it has spent on Quantum research, but funding for basic research which includes quantum physics was $US101 billion in 2015 an absolutely massive increase from the $US1.9 billion the country spent in 2005.

Scientists in the US, Canada, Europe and Japan are also rushing to exploit the power of particle physics to create secure communication systems, but Chinas latest experiment puts the country well ahead of the pack.

With AFP

China launched the world's first quantum satellite on top of a Long March-2D rocket from the Jiuquan Satellite Launch Center in northwest China. Picture: ZumaSource:Supplied

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China sets new record for quantum entanglement en route to build new communication network - NEWS.com.au

A Chinese satellite has split pairs of "entangled photons" and transmitted them to separate ground stations 745 miles (1,200 kilometers) apart, smashing the previous distance record for such a feat and opening new possibilities in quantum communication.

In quantum physics, when particles interact with each other in certain ways they become "entangled." This essentially means they remain connected even when separated by large distances, so that an action performed on one affects the other.

In a new study published online today (June 15) in the journal Science, researchers report the successful distribution of entangled photon pairs to two locations on Earth separated by 747.5 miles (1,203 km). [The 18 Biggest Unsolved Mysteries in Physics]

Quantum entanglement has interesting applications for testing the fundamental laws of physics, but also for creating exceptionally secure communication systems, scientists have said. That's because quantum mechanics states that measuring a quantum system inevitably disturbs it, so any attempt to eavesdrop is impossible to hide.

But, it's hard to distribute entangled particles normally photons over large distances. When traveling through air or over fiber-optic cables, the environment interferes with the particles, so with greater distances, the signal decays and becomes too weak to be useful.

In 2003, Pan Jianwei, a professor of quantum physics at the University of Science and Technology of China, started work on a satellite-based system designed to beam entangled photon pairs down to ground stations. The idea was that because most of the particle's journey would be through the vacuum of space, this system would introduce considerably less environmental interference.

"Many people then thought it [was] a crazy idea, because it was very challenging already doing the sophisticated quantum-optics experiments inside a well-shielded optical table," Pan told Live Science. "So how can you do similar experiments at thousand-kilometers distance scale and with the optical elements vibrating and moving at a speed of 8 kilometers per second [5 miles per second]?"

In the new study, researchers used China's Micius satellite, which was launched last year, to transmit the entangled photon pairs. The satellite features an ultrabright entangled photon source and a high-precision acquiring, pointing and tracking (APT) system that uses beacon lasers on the satellite and at three ground stations to line up the transmitter and receivers.

Once the photons reached the ground stations, the scientists carried out tests and confirmed that the particles were still entangled despite having traveled between 994 miles and 1,490 miles (1,600 and 2,400 km), depending on what stage of its orbit the satellite was positioned at.

Only the lowest 6 miles (10 km) of Earth's atmosphere are thick enough to cause significant interference with the photons, the scientists said. This means the overall efficiency of their link was vastly higher than previous methods for distributing entangled photons via fiber-optic cables, according to the scientists. [Twisted Physics: 7 Mind-Blowing Findings]

"We have already achieved a two-photon entanglement distribution efficiency a trillion times more efficient than using the best telecommunication fibers," Pan said. "We have done something that was absolutely impossible without the satellite."

Apart from carrying out experiments, one of the potential uses for this kind of system is for "quantum key distribution," in which quantum communication systems are used to share an encryption key between two parties that is impossible to intercept without alerting the users. When combined with the correct encryption algorithm, this system is uncrackable even if encrypted messages are sent over normal communication channels, experts have said.

Artur Ekert, a professor of quantum physics at the University of Oxford in the United Kingdom, was the first to describe how entangled photons could be used to transmit an encryption key.

"The Chinese experiment is quite a remarkable technological achievement," Ekert told Live Science. "When I proposed the entangled-based quantum key distribution back in 1991 when I was a student in Oxford, I did not expect it to be elevated to such heights!"

The current satellite is not quite ready for use in practical quantum communication systems, though, according to Pan. For one, its relatively low orbit means each ground station has coverage for only about 5 minutes each day, and the wavelength of photons used means it can only operate at night, he said.

Boosting coverage times and areas will mean launching new satellites with higher orbits, Pan said, but this will require bigger telescopes, more precise tracking and higher link efficiency. Daytime operation will require the use of photons in the telecommunications wavelengths, he added.

But while developing future quantum communication networks will require considerable work, Thomas Jennewein, an associate professor at the University of Waterloo's Institute for Quantum Computing in Canada, said Pan's group has demonstrated one of the key building blocks.

"I have worked in this line of research since 2000 and researched on similar implementations of quantum- entanglement experiments from space, and I can therefore very much attest to the boldness, dedication and skills that this Chinese group has shown," he told Live Science.

Original article on Live Science.

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New Quantum-Entanglement Record Could Spur Hack-Proof Communications - Yahoo News

Quantum mechanics is the body of scientific laws that describe the wacky behavior of photons, electrons and the other particles that make up the universe.

Quantum mechanics is the branch of physics relating to the very small.

It results in what may appear to be some very strange conclusions about the physical world. At the scale of atoms and electrons, many of the equations ofclassical mechanics, which describe how things move at everyday sizes and speeds, cease to be useful. In classical mechanics, objects exist in a specific place at a specific time. However, in quantum mechanics, objects instead exist in a haze of probability; they have a certain chance of being at point A, another chance of being at point B and so on.

Quantum mechanics (QM) developed over many decades, beginning as a set of controversial mathematical explanations of experiments that the math of classical mechanics could not explain. It began at the turn of the 20th century, around the same time that Albert Einstein published histheory of relativity, a separate mathematical revolution in physics that describes the motion of things at high speeds. Unlike relativity, however, the origins of QM cannot be attributed to any one scientist. Rather, multiple scientists contributed to a foundation of three revolutionary principles that gradually gained acceptance and experimental verification between 1900 and 1930. They are:

Quantized properties: Certain properties, such as position, speed and color, can sometimes only occur in specific, set amounts, much like a dial that "clicks" from number to number. This challenged a fundamental assumption of classical mechanics, which said that such properties should exist on a smooth, continuous spectrum. To describe the idea that some properties "clicked" like a dial with specific settings, scientists coined the word "quantized."

Particles of light: Light can sometimes behave as a particle. This was initially met with harsh criticism, as it ran contrary to 200 years of experiments showing that light behaved as a wave; much like ripples on the surface of a calm lake. Light behaves similarly in that it bounces off walls and bends around corners, and that the crests and troughs of the wave can add up or cancel out. Added wave crests result in brighter light, while waves that cancel out produce darkness. A light source can be thought of as a ball on a stick beingrhythmically dipped in the center of a lake. The color emitted corresponds to the distance between the crests, which is determined by the speed of the ball's rhythm.

Waves of matter: Matter can also behave as a wave. This ran counter to the roughly 30 years of experiments showing that matter (such as electrons) exists as particles.

In 1900, German physicist Max Planck sought to explain the distribution of colors emitted over the spectrum in the glow of red-hot and white-hot objects, such as light-bulb filaments. When making physical sense of the equation he had derived to describe this distribution, Planck realized it implied that combinations of only certaincolors(albeit a great number of them) were emitted, specifically those that were whole-number multiples of some base value. Somehow, colors were quantized! This was unexpected because light was understood to act as a wave, meaning that values of color should be a continuous spectrum. What could be forbiddingatomsfrom producing the colors between these whole-number multiples? This seemed so strange that Planck regarded quantization as nothing more than a mathematical trick. According to Helge Kragh in his 2000 article in Physics World magazine, "Max Planck, the Reluctant Revolutionary," "If a revolution occurred in physics in December 1900, nobody seemed to notice it. Planck was no exception "

Planck's equation also contained a number that would later become very important to future development of QM; today, it's known as "Planck's Constant."

Quantization helped to explain other mysteries of physics. In 1907, Einstein used Planck's hypothesis of quantization to explain why the temperature of a solid changed by different amounts if you put the same amount of heat into the material but changed the starting temperature.

Since the early 1800s, the science ofspectroscopyhad shown that different elements emit and absorb specific colors of light called "spectral lines." Though spectroscopy was a reliable method for determining the elements contained in objects such as distant stars, scientists were puzzled aboutwhyeach element gave off those specific lines in the first place. In 1888, Johannes Rydberg derived an equation that described the spectral lines emitted by hydrogen, though nobody could explain why the equation worked. This changed in 1913 whenNiels Bohrapplied Planck's hypothesis of quantization to Ernest Rutherford's 1911 "planetary" model of the atom, which postulated that electrons orbited the nucleus the same way that planets orbit the sun. According toPhysics 2000(a site from the University of Colorado), Bohr proposed that electrons were restricted to "special" orbits around an atom's nucleus. They could "jump" between special orbits, and the energy produced by the jump caused specific colors of light, observed as spectral lines. Though quantized properties were invented as but a mere mathematical trick, they explained so much that they became the founding principle of QM.

In 1905, Einstein published a paper, "Concerning an Heuristic Point of View Toward the Emission and Transformation of Light," in which he envisioned light traveling not as a wave, but as some manner of "energy quanta." This packet of energy, Einstein suggested, could "be absorbed or generated only as a whole," specifically when an atom "jumps" between quantized vibration rates. This would also apply, as would be shown a few years later, when an electron "jumps" between quantized orbits. Under this model, Einstein's "energy quanta" contained the energy difference of the jump; when divided by Plancks constant, that energy difference determined the color of light carried by those quanta.

With this new way to envision light, Einstein offered insights into the behavior of nine different phenomena, including the specific colors that Planck described being emitted from a light-bulb filament. It also explained how certain colors of light could eject electrons off metal surfaces, a phenomenon known as the "photoelectric effect." However, Einstein wasn't wholly justified in taking this leap, said Stephen Klassen, an associate professor of physics at the University of Winnipeg. In a 2008 paper, "The Photoelectric Effect: Rehabilitating the Story for the Physics Classroom," Klassen states that Einstein's energy quanta aren't necessary for explaining all of those nine phenomena. Certain mathematical treatments of light as a wave are still capable of describing both the specific colors that Planck described being emitted from a light-bulb filament and the photoelectric effect. Indeed, in Einstein's controversial winning of the 1921Nobel Prize, the Nobel committee only acknowledged "his discovery of the law of the photoelectric effect," which specifically did not rely on the notion of energy quanta.

Roughly two decades after Einstein's paper, the term "photon" was popularized for describing energy quanta, thanks to the 1923 work of Arthur Compton, who showed that light scattered by an electron beam changed in color. This showed that particles of light (photons) were indeed colliding with particles of matter (electrons), thus confirming Einstein's hypothesis. By now, it was clear that light could behave both as a wave and a particle, placing light's "wave-particle duality" into the foundation of QM.

Since the discovery of the electron in 1896, evidence that all matter existed in the form of particles was slowly building. Still, the demonstration of light's wave-particle duality made scientists question whether matter was limited to actingonlyas particles. Perhaps wave-particle duality could ring true for matter as well? The first scientist to make substantial headway with this reasoning was a French physicist named Louis de Broglie. In 1924, de Broglie used the equations of Einstein'stheory of special relativityto show that particles can exhibit wave-like characteristics, and that waves can exhibit particle-like characteristics. Then in 1925, two scientists, working independently and using separate lines of mathematical thinking, applied de Broglie's reasoning to explain how electrons whizzed around in atoms (a phenomenon that was unexplainable using the equations ofclassical mechanics). In Germany, physicist Werner Heisenberg (teaming with Max Born and Pascual Jordan) accomplished this by developing "matrix mechanics." Austrian physicist ErwinSchrdingerdeveloped a similar theory called "wave mechanics." Schrdinger showed in 1926 that these two approaches were equivalent (though Swiss physicist Wolfgang Pauli sent anunpublished resultto Jordan showing that matrix mechanics was more complete).

The Heisenberg-Schrdinger model of the atom, in which each electron acts as a wave (sometimes referred to as a "cloud") around the nucleus of an atom replaced the Rutherford-Bohr model. One stipulation of the new model was that the ends of the wave that forms an electron must meet. In "Quantum Mechanics in Chemistry, 3rd Ed." (W.A. Benjamin, 1981), Melvin Hanna writes, "The imposition of the boundary conditions has restricted the energy to discrete values." A consequence of this stipulation is that only whole numbers of crests and troughs are allowed, which explains why some properties are quantized. In the Heisenberg-Schrdinger model of the atom, electrons obey a "wave function" and occupy "orbitals" rather than orbits. Unlike the circular orbits of the Rutherford-Bohr model, atomic orbitals have a variety of shapes ranging from spheres to dumbbells to daisies.

In 1927, Walter Heitler and Fritz London further developed wave mechanics to show how atomic orbitals could combine to form molecular orbitals, effectively showing why atoms bond to one another to formmolecules. This was yet another problem that had been unsolvable using the math of classical mechanics. These insights gave rise to the field of "quantum chemistry."

Also in 1927, Heisenberg made another major contribution to quantum physics. He reasoned that since matter acts as waves, some properties, such as an electron's position and speed, are "complementary," meaning there's a limit (related to Planck's constant) to how well the precision of each property can be known. Under what would come to be called "Heisenberg'suncertainty principle," it was reasoned that the more precisely an electron's position is known, the less precisely its speed can be known, and vice versa. This uncertainty principle applies to everyday-size objects as well, but is not noticeable because the lack of precision is extraordinarily tiny. According to Dave Slaven of Morningside College (Sioux City, IA), if a baseball's speed is known to within aprecision of 0.1 mph, the maximum precision to which it is possible to know the ball's position is 0.000000000000000000000000000008 millimeters.

The principles of quantization, wave-particle duality and the uncertainty principle ushered in a new era for QM. In 1927, Paul Dirac applied a quantum understanding of electric and magnetic fields to give rise to the study of "quantum field theory" (QFT), which treated particles (such as photons and electrons) as excited states of an underlying physical field. Work in QFT continued for a decade until scientists hit a roadblock: Many equations in QFT stopped making physical sense because they produced results of infinity. After a decade of stagnation, Hans Bethe made a breakthrough in 1947 using a technique called "renormalization." Here, Bethe realized that all infinite results related to two phenomena (specifically "electron self-energy" and "vacuum polarization") such that the observed values of electron mass and electron charge could be used to make all the infinities disappear.

Since the breakthrough of renormalization, QFT has served as the foundation for developing quantum theories about the four fundamental forces of nature: 1) electromagnetism, 2) the weak nuclear force, 3) the strong nuclear force and 4) gravity. The first insight provided by QFT was a quantum description of electromagnetism through "quantum electrodynamics" (QED), which made strides in the late 1940s and early 1950s. Next was a quantum description of the weak nuclear force, which was unified with electromagnetism to build "electroweak theory" (EWT) throughout the 1960s. Finally came a quantum treatment of the strong nuclear force using "quantum chromodynamics" (QCD) in the 1960s and 1970s. The theories of QED, EWT and QCD together form the basis of theStandard Modelof particle physics. Unfortunately, QFT has yet to produce a quantum theory of gravity. That quest continues today in the studies of string theory and loop quantum gravity.

Robert Coolman is a graduate researcher at the University of Wisconsin-Madison, finishing up his Ph.D. in chemical engineering. He writes about math, science and how they interact with history. Follow Robert@PrimeViridian. Followus@LiveScience,Facebook&Google+.

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What Is Quantum Mechanics? - livescience.com

Quantum physics is an often mind-boggling branch of science filled with strange behavior and bizarre implications. For many people, the mere mention of the term is enough to send us hurtling in the opposite direction, like an electron bouncing off the center of an atom.

But evidence is mounting that the future of technology lies in quantum mechanics, which focuses on how the smallest things in our universe work. And a new breakthrough by scientists in China has just brought the world one very big step closer to this quantum revolution. Hundreds of miles closer, in fact. So its as good a time as any to understand why quantum physics is making such waves.

An Atlas 5 rocket, a national security satellite, launched from California in 2008. Chinese physicists have used a satellite to beat the distance record for quantum entanglement. Gene Blevins/Reuters

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Quantum physics is all about waves. And particles. Together. Sort of.

Mostly, we think of light as something that occurs in waves and matter as distinct particles. But theorist Max Plancks attempt in 1900 to explain observations about colors emitted from hot objects started scientists down a path that transformed our understanding of how life works at the very smallest scale.

The first step was realizing that light behaves like a stream of individual particles, called photons. Albert Einstein came to this conclusion following Plancks work. Each photon contains a discrete amount of energy.

Subsequent research by Niels Bohr and others disrupted what physicists understood about electrons, the negatively charged particles that swirl around the heavy centers of the atoms that make up the elements (gold, silver, potassium, calcium, etc.) that in turn make up matter. That disruption was accentuated by Louis de Broglie, who realized that if light can behave like a particle, then maybe electrons, which physicists had always thought of as particles, could behave like waves. Numerous experiments proved that to be the case. Photons behave like waves and particles. Electrons behavelike waves and particles. The type of measurement you do determines how a photon or an electron behave.

One of the most intriguing effects of quantum physics is something called entanglement. With quantum entanglement, two particles derived from the same source behave the same way, even when they are far apart. The state of either particle cannot be determined until it is measured, and the act of measuring is what determines its state. And the measurement of one particle affects the measurement of the other particle. This thinking is embodied by Erwin Schrdingers thought problem about his famous cat.

If you split photon A into a photon pairB and Cmeasuring B will tell you, with absolute certainty, the measure of C. Paul Kwiat, physicist at the University of Illinois, gives the analogy of flipping a coin. If one flipped coin results in heads, heads, tails, heads, tails, tails, head, then the entangled coin, placed hundreds of miles away, would follow the same sequence. Thats not a behavior you see with coins, says Kwiat. Thats where quantum entanglement is pretty weird. Two things hundreds of miles away behaving as one: Thats quantum entanglement. And its real. Albert Einstein called it spuckhafte ferwirklung, or spooky action at a distance.

For more on the history of quantum physics and the entanglement phenomenon, author Chad Orzel, who teaches physics at Union College in Schenectady, New York, has some excellent videos.

Beyond the weirdness factor, quantum entanglement has broad implications for computing and information sharing. Entanglement distributionfor example, the splitting of a single photon into two linked photonscould be used to create a secure internet connection. The technology, called quantum cryptography, would allow the users to detect any eavesdropper on the channel. The reason you can detect the eavesdropper is that such an intruder would necessarily alter the entangled photons by his or her presence.

The principle allows for a secure communication channel that is unhackable, says Jonathan Dowling, a physicist at Louisiana State University When the Chinese roll out this type of communications nationwide, which is their plan, says Dowling, then no matter how many NSA computers you string together, you are never going to be able to tap into their system.

A new study in Science, by Juan Yin and colleagues at the University of Science and Technology in China and several other institutions there, has brought this future technology within much closer reach. The researchers split a photon on a satellite and sent the two resulting photons in two different directions, aimed at ground stations in China. The ground stations were more than 700 miles apart from one another. The distance from the satellite, which was constantly in motion, to each ground station varied from 300 to 1,200 miles.

The researchers managed to send photon pairs to different ground stations repeatedly and confirmed that the photons were entangled. Using a laser pointer-like source, they made about 6 million photon pairs per second. About one pair per second reached the ground stations. Kwiat says its like throwing a dime into a toll booth bucket while driving at high speed, only youre throwing a much tinier object from much farther awayand at a much faster speed. Measurements confirmed that the photon pairs had the same polarization, proving that they were entangled.

Although previous studies have managed to achieve similar results, never has it been done over such a great distance and from a satellite. (The prior record demonstrated entanglement across two of the Canary Islands, about 89 miles apart.) Its a beautiful experiment, says Kwiat. They demonstrated the persistence of entanglement over a longer distance than any experiment before by roughly a factor of 10.

Dowling says that this achievement proves that the quantum-based technologies many physicists envision are attainable. The long-term goal is to build a quantum internet where future computers around the globe are linked together in an uncrackable network of extraordinary computational power, says Dowling. The satellite will go down in history as the first link in the quantum internet.

The Chinese physicists are not the only team on the quest for this technology. Quantum cryptography systems are commercially available and researchers in several countries, including the U.S., Canada, Italy and Singapore are also forging the way ahead, says Kwiat, who is among them. Google is also working on quantum information science.

Still, the new study is a huge breakthrough because it proves entanglement can be achieved from a satellite and across this large distance. We have done something that was absolutely impossible without the satellite, says senior author Jian-Wei Pan. The next step, he says, is to perform more experiments with light from space, across yet longer distances and at faster speeds, with a goal of controlling quantum states and understanding how gravity affects quantum behavior.

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Cybersecurity Attacks Are a Global Threat. Chinese Scientists Have the Answer: Quantum Mechanics - Newsweek

Chinese scientists have just set a record in quantum physics.

For the first time, pairs of entangled photons have been beamed from a satellite in orbit to two receiving stations almost 1,500 miles away on on Earth.

At the same time, the researchers were able to deliberately separate the entangled photon pairs along a greater distance than has ever been recorded.

The experiment, described Thursday in the journal Science, represents the first measurable proof of an idea that has long been theorized but never tested, experts said.

This is the first time you have a quantum channel between a satellite and the ground that you can actually use, said Norbert Ltkenhaus, a professor at the Institute for Quantum Computing at the University of Waterloo in Canada who was not involved in the new work. People have been talking about doing it for many, many years, but these guys actually did it.

Keep reading to learn what this new work means, and why it matters.

Great question. For starters, a photon is a tiny particle of light. In fact, it's the smallest unit that light can be broken into. It has no mass and no charge.

Entangled photons are a pair of photons whose properties are linked, and remain that way no matter how far apart they get.

If you make a measurement on one of the photons, you get a perfectly correlated outcome on the other member of the pair, Ltkenhaus said.

And that will hold true not matter how many times you look at them.

One measurement alone doesnt tell you they are entangled, you need to repeat it many times, he said. With entangled photons no matter what you measure, or how many times you measure, or which side of the pair you measure, you always get perfect correlation.

Another great question. This one is more difficult to answer.

Scientists have not been able to explain why entanglement occurs. All they know is that it exists.

Einstein referred to the phenomena of entanglement as spooky action at a distance. Others have said it is kind of like the physics version of voodoo.

They built a special satellite to do it.

The spacecraft, nicknamed Micius after a famous 5th century Chinese scientist, launched in August 2016.

It is loaded with a special crystal that can split a single incoming photon into two daughter photons with joint properties. For this experiment, instruments on the satellite separated the entangled photons and sent them to different receiving stations on Earth.

To do this, Micius had to aim at its targets with an amazing degree of precision, said Jian-Wei Pan, a physicist at the University of Science and Technology of China who led the work.

Its the equivalent of clearly seeing a human hair at a distance of 900 feet away, he said.

It is extreme. And, experts say, challenging.

Designing, launching and operating a satellite with this capability is no easy feat, Ltkenhaus said. I see this as a great engineering triumph.

But, as the study demonstrates, using a satellite to send beams of entangled photons to Earth is a better strategy than using optical fibers to distribute them.

The greatest distance scientists have been able to separate entangled photons using optical fibers is 62 miles. By sending the entangled photons through space, Pan and his team were able to separate entangled photons by more than 620 miles.

Not immediately, but eventually, it probably will.

For example, distributing entangled photons over large distances could be used to establish unhackable communications via whats known as quantum cryptography.

This application relies on another strange aspect of quantum mechanics namely that the simple act of observing a photon disturbs it and causes it to change its orientation.

Scientists have already been able to establish secure, quantum channels using fiber optics, but there is a limit to how far those can stretch.

Using the space-based quantum channel, the authors have shown it is possible to significantly extend the distance over which one can perform such a secure communication, said Jrgen Volz, a physicist at the Vienna Center for Quantum Science and Technology who was not involved in the work.

In the time of the Internet, when more and more sensitive information is shared and exchanged via the web, this is of tremendous importance, he said.

But experts say an application like that may still be 10 years away.

Although the experiment was successful, the rate of sending and receiving entangled photons described in the paper was still quite low. Of nearly 6 million entangled photon pairs generated by Micius each second, only one pair was detected at stations here on Earth.

The communication rates here are not yet sufficient for a practical application, said Wenjamin Rosenfeld, a physicist at the Ludwig-Maximilians University in Munich.

However, he added that the mission represents a proof-of-principle demonstration of a quantum communication protocol that could be available in the near future.

Pan put it this way: This is the first baby step for quantum entanglement experiments going into space. It is really new!

deborah.netburn@latimes.com

Do you love science? I do! Follow me @DeborahNetburn and "like" Los Angeles Times Science & Health on Facebook.

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Chinese satellite breaks a quantum physics record, beams entangled photons from space to Earth - Los Angeles Times