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Direct measurements of the wave nature of matter, previously only known from theory

Direct measurements of the wave nature of matter, previously only known from theory | Amazing Science |

At the heart of quantum mechanics is the wave-particle duality: matter and light possess both wave-like and particle-like attributes. Typically, the wave-like properties are inferred indirectly from the behavior of many electrons or photons, though it's sometimes possible to study them directly. However, there are fundamental limitations to those experiments—namely information about the wave properties of matter that is inherently inaccessible.

And therein lies a loophole: two groups used indirect experiments to reconstruct the wave structure of electrons. A.S. Stodolna and colleagues manipulated hydrogen atoms to measure their electron's wave structure, validating more than 30 years of theoretical work on the phenomenon known as the Stark effect. A second experiment by Daniel Lüftner and collaborators reconstructed the electronic structure of individual organic molecules through repeated scanning, with each step providing a higher resolution. In both cases, the researchers were able to match theoretical predictions to their results, verifying some previously challenging aspects of quantum mechanics.

Neither a wave nor a particle description can describe all experimental results obtained by physicists. Photons interfere with each other and themselves like waves when they pass through openings in a barrier, yet they show up as individual points of light on a phosphorescent screen. Electrons create orbital patterns inside atoms described by three-dimensional waves, yet they undergo collisions as if they were particles. Certain experiments are able to reconstruct the distribution of electric charge inside materials, which appears very wave-like, yet the atoms look like discrete bodies in those same experiments.

The wave functions in the Stark effect have a peculiar mathematical property, one which Stodolna and colleagues recreated in the lab. They separated individual hydrogen atoms from hydrogen sulfide (H2S) molecules, then subjected them to a series of laser pulses to induce specific energy transitions inside the atoms. By measuring the ways the light scattered, the researchers were able to recreate the predicted wave functions—the first time this has been accomplished. The authors also argued that this method, known as photoionization microscopy, could be used to reconstruct wavefunctions for other atoms and molecules.

Lüftner and colleagues took a different approach and examined the wave functions of organic molecules chemically attached (adsorbed) on a silver surface. Specifically, they looked at pentacene (C22H14) and the easy-to-remember compound perylene-3,4,9,10-tetracboxylic dianhydride (or PTCDA, C24H8O6). Unlike hydrogen, the wave functions for these molecules cannot be calculated exactly. They usually require using "ab initio" computer models.

The researchers were particularly interested in finding the phase, that bit of the wave function that can't be measured directly. They determined that they could reconstruct it by using the particular way the molecules bonded to the surface, which enhanced their response to photons of a specific wavelength. The experiment involved taking successive iterative measurements by exciting the molecules using light, then measuring the angles at which the photons were scattered away.

Reconstructing the phase of the wave function required exploiting the particular mathematical form it took in this system. Specifically, the waves had a relatively sharp edge, allowing the researchers to make an initial guess and then refine the value as they took successive measurements. Even with this sophisticated process, they were only able to determine the phase to an arbitrary precision—something entirely to be expected from fundamental quantum principles. However, they were able to experimentally reconstruct the entire wave function of a molecule. There was previously no way to check whether our calculated wave functions were accurate or not.


Physical Review Letters, 2013. DOI: 10.1103/PhysRevLett.110.213001 and
PNAS, 2013. DOI: 10.1073/pnas.1315716110  (About DOIs).

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How to Survive a Nuclear Explosion

How to Survive a Nuclear Explosion | Amazing Science |
New mathematical model tells you whether to stay put—or run like hell

It begins with a flash brighter than the sun. Trees, fences, and people immediately catch fire. The only reason you survive is because you run inside and dive into the cast-iron tub just as the shock wave arrives. You stumble to your lopsided front door and look out on the burning ruin of your neighborhood. The deadly radioactive fallout is on its way. Should you stay in your wobbling house or run across town to the public library to shelter in its basement? A new mathematical model may have the answer.

The model is the brainchild of Michael Dillon, an atmospheric scientist at Lawrence Livermore National Laboratory in California. He started exploring the topic about 5 years ago after the U.S. government called for more research on nuclear shelters. During the Cold War, scientists modeled almost every imaginable consequence of a nuclear explosion. But Dillon found a gap in the sheltering strategies for people far enough from ground zero to survive the initial blast but close enough to face deadly fallout. He focused on a single low-yield nuclear detonation like those that destroyed Hiroshima and Nagasaki. The world’s nuclear arsenal has grown far more powerful—today’s warheads can inflict thousands of times more damage—but security experts believe that low-yield bombs are the kind most likely to be used by terrorists.

Dillon simplified the calculation by assuming that you are totally exposed while running to safer shelter; he also ignored complexities such as limited shelter capacities. In the end, the math boiled down to a single critical number: the ratio of the time you spend hunkering down in your first shelter to the time you spend moving to the high-quality shelter. Then Dillon worked out what would happen with a variety of shelter options and transit times.

The results surprised him. For low-yield nuclear detonations, you can do far better than just sheltering in place, but you’ll need a watch and good knowledge of your surroundings. If your current shelter is poor and higher quality shelter is less than 5 minutes away, the model suggests that you should run there as soon as you can. If you have poor shelter but higher quality shelter is available farther away, you should get to that high-quality shelter no later than 30 minutes after detonation. Depending on the size of the city, if everyone follows this advice, it could save between 10,000 and 100,000 lives, Dillon reports online today in the Proceedings of the Royal Society A.

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Why Einstein will never be wrong?

Why Einstein will never be wrong? | Amazing Science |
One of the benefits of being an astrophysicist is your weekly email from someone who claims to have 'proven Einstein wrong'.

These either contain no mathematical equations and use phrases such as "it is obvious that..", or they are page after page of complex equations with dozens of scientific terms used in non-traditional ways. They all get deleted pretty quickly, not because astrophysicists are too indoctrinated in established theories, but because none of them acknowledge how theories get replaced.

Then in the early 1900s Einstein proposed a different model known as general relativity. The basic premise of this theory is that gravity is due to the curvature of space and time by masses. Even though Einstein's gravity model is radically different from Newton's, the mathematics of the theory shows that Newton's equations are approximate solutions to Einstein's equations. Everything Newton's gravity predicts, Einstein's does as well. But Einstein also allows us to correctly model black holes, the big bang, the precession of Mercury's orbit, time dilation, and more, all of which have been experimentally validated.

So Einstein trumps Newton. But Einstein's theory is much more difficult to work with than Newton's, so often we just use Newton's equations to calculate things. For example, the motion of satellites, or exoplanets. If we don't need the precision of Einstein's theory, we simply use Newton to get an answer that is "good enough." We may have proven Newton's theory "wrong", but the theory is still as useful and accurate as it ever was.

To begin with, Einstein's gravity will never be proven wrong by a theory. It will be proven wrong by experimental evidence showing that the predictions of general relativity don't work. Einstein's theory didn't supplant Newton's until we had experimental evidence that agreed with Einstein and didn't agree with Newton. So unless you have experimental evidence that clearly contradicts general relativity, claims of "disproving Einstein" will fall on deaf ears.

The other way to trump Einstein would be to develop a theory that clearly shows how Einstein's theory is an approximation of your new theory, or how the experimental tests general relativity has passed are also passed by your theory. Ideally, your new theory will also make new predictions that can be tested in a reasonable way. If you can do that, and can present your ideas clearly, you will be listened to. String theory and entropic gravity are examples of models that try to do just that.

But even if someone succeeds in creating a theory better than Einstein's (and someone almost certainly will), Einstein's theory will still be as valid as it ever was. Einstein won't have been proven wrong, we'll simply understand the limits of his theory.

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Magnetic metamaterial superlens extends range of wireless power transfer

Magnetic metamaterial superlens extends range of wireless power transfer | Amazing Science |

Inventor Nikola Tesla imagined the technology to transmit energy through thin air almost a century ago, but experimental attempts at the feat have so far resulted in cumbersome devices that only work over very small distances. But now, Duke University researchers have demonstrated the feasibility of wireless power transfer using low-frequency magnetic fields over distances much larger than the size of the transmitter and receiver.

The advance comes from a team of researchers in Duke's Pratt School of Engineering, who used metamaterials to create a "superlens" that focuses magnetic fields. The superlens translates the magnetic field emanating from one power coil onto its twin nearly a foot away, inducing an electric current in the receiving coil.

The experiment was the first time such a scheme has successfully sent power through the air with an efficiency many times greater than what could be achieved with the same setup minus the superlens. "For the first time we have demonstrated that the efficiency of magneto-inductive wireless power transfer can be enhanced over distances many times larger than the size of the receiver and transmitter," said Yaroslav Urzhumov, assistant research professor of electrical and computer engineering at Duke University. "This is important because if this technology is to become a part of everyday life, it must conform to the dimensions of today's pocket-sized mobile electronics."

In the experiment, Yaroslav and the joint Duke-Toyota team created a square superlens, which looks like a few dozen giant Rubik's cubes stacked together. Both the exterior and interior walls of the hollow blocks are intricately etched with a spiraling copper wire reminiscent of a microchip. The geometry of the coils and their repetitive nature form a metamaterial that interacts with magnetic fields in such a way that the fields are transmitted and confined into a narrow cone in which the power intensity is much higher.

"If your electromagnet is one inch in diameter, you get almost no power just three inches away," said Urzhumov. "You only get about 0.1 percent of what's inside the coil." But with the superlens in place, he explained, the magnetic field is focused nearly a foot away with enough strength to induce noticeable electric current in an identically sized receiver coil.

Urzhumov noted that metamaterial-enhanced wireless power demonstrations have been made before at a research laboratory of Mitsubishi Electric, but with one important caveat: the distance the power was transmitted was roughly the same as the diameter of the power coils. In such a setup, the coils would have to be quite large to work over any appreciable distance.

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Rice University builds RAMBO — a small but powerful magnet

Rice University builds RAMBO — a small but powerful magnet | Amazing Science |

RAMBO (Rice Advanced Magnet with Broadband Optics) — a tabletop magnetic pulse generator that does the work of a room-sized machine — has been developed by Rice University scientists. The device will allow researchers who visit the university to run spectroscopy-based experiments on materials in pulsed magnetic fields of up to 30 tesla. A typical high-resolution magnetic resonance imaging system used in hospitals is in the 0.5-tesla to 3.0-tesla range in strength.

The Rice lab of physicist Junichiro Kono created RAMBO in collaboration with Hiroyuki Nojiri at the Institute for Materials Research at Tohoku University in Sendai, Japan.

Aside from its size and powerful performance, RAMBO has windows that allow researchers to directly send a laser beam to the sample and collect data at close range, instead of via an optical fiber.

“RAMBO finally gives us the ability to combine ultrastrong magnetic fields and very short and intense optical pulses; it’s a combination of two extreme conditions,” said Kono.

RAMBO is possible, Kono said, because of Nojiri’s development of a small and light mini-coil magnet. A little bigger than a spool of thread, the magnet allows Rice researchers to perform on campus many of the experiments they once carried out at the National High Magnetic Field Laboratory at Florida State University or at Los Alamos National LaboratoryThe Florida State facility has produced continuous magnetic fields of 45 tesla; Los Alamos has produced pulses over 100 tesla.

“I would say we’ve been able to do 80 percent of the experiments here that we used to have to do elsewhere,” Kono said. “And that’s not all. There are things that only we can do here. This is a unique system that doesn’t exist anywhere else in the world.

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Scientists find a practical test for string theory

Scientists find a practical test for string theory | Amazing Science |

Scientists at Towson University in Towson, Maryland, have identified a practical, yet overlooked, test of string theory based on the motions of planets, moons and asteroids, reminiscent of Galileo's famed test of gravity by dropping balls from the Tower of Pisa.

String theory is infamous as an eloquent theoretical framework to understand all forces in the universe —- a so-called "theory of everything" —- that can't be tested with current instrumentation because the energy level and size scale to see the effects of string theory are too extreme.

Yet inspired by Galileo Galilei and Isaac Newton, Towson University scientists say that precise measurements of the positions of solar-system bodies could reveal very slight discrepancies in what is predicted by the theory of general relativity and the equivalence principle, or establish new upper limits for measuring the effects of string theory. String theory hopes to provide a bridge between two well-tested yet incompatible theories that describe all known physics: Einstein's general relativity, our reigning theory of gravity; and the standard model of particle physics, or quantum field theory, which explains all the forces other than gravity.

Building on work done by Kenneth Nordtvedt and others beginning in the 1970s, Overduin and his collaborators consider three possible signatures of equivalence principle violation in the solar system: departures from Kepler's Third Law of planetary motion; drift of the stable Lagrange points; and orbital polarization (also known as the Nordtvedt effect), whereby the distance between two bodies like the Earth and Moon oscillates due to differences in acceleration toward a third body like the Sun.

To date, there is no evidence for any of these effects. Indeed, the standard astronomical ephemeris assumes the validity of Kepler's Third Law in deriving such fundamental quantities as the length of the Astronomical Unit. But all observations in science involve some degree of experimental uncertainty. The approach of Overduin's team is to use these experimental uncertainties themselves to obtain upper limits on possible violations of the equivalence principle by the planets, moons and Trojan asteroids in the solar system.

"The Saturnian satellites Tethys and Dione make a particularly fascinating test case," said Warecki, who is presenting this work at Session 109 at the AAS meeting today. "Tethys is made almost entirely of ice, while Dione possesses a significantly rocky core. And both have Trojan companions."

"The limits obtained in this way are not as sensitive as those from dedicated torsion-balance or laser-ranging tests," said Mitcham. "But they are uniquely valuable as potential tests of string theory nonetheless because they cover a much wider range of test-body materials."

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Toshiba invents quantum cryptography network that even the NSA can’t hack

Toshiba invents quantum cryptography network that even the NSA can’t hack | Amazing Science |
If you've got communications that absolutely cannot be intercepted—whether you're a NSA whistleblower, the president of Mexico, or Coca-Cola—quantum cryptography is the way to go.

new research paper from scientists at Toshiba brings quantum cryptography a baby-step closer to the masses. The paper, published today in Nature, explains how to expand a point-to-point quantum network with only two users into a “quantum access network” with up to 64 users.

“This kind of communication cannot be defeated by future advances in computing power, nor new mathematical algorithms, nor fancy new engineering,” said co-author Andrew Shields, head of the Quantum Information Group of Toshiba Research Europe. “As long as the laws of physics hold true, it will ensure that your communications are fully secured.”

A quantum network uses specially polarized photons to encode an encryption key—a very long series of numbers and letters that can unlock a digital file. The photons are then sent down a fiber optic cable until they reach their destination, a photon detector, which counts them, and delivers the key to the intended recipient. If the photons are interfered with, the individual packets of information are forever altered and the recipient can see the telltale signs of tampering.

The Toshiba team focused its efforts on improving the photon detector, and created a system that counts up to 1 billion photons per second, which makes it feasible to add more people to the network. “Our breakthrough is we’ve developed an architecture that is point-to-multipoint. This greatly increase the number of potential users in the network, and reduces costs,” Shields said.

Current quantum cryptography systems from companies like ID Quantique start at around $50,000, and only connect two parties at a time. “If up to 64 people can share a single photon detector than you can spread out those costs,” Shields said.

The next step toward mainstreaming quantum crypto is increasing the distance that photons can travel before they degrade—currently the record is 200 km (124 miles) using a dedicated fiber optic cable. But researchers are working on ways to transmit quantum bits on so-called “noisy” fiber that carries other information, which means that the day may not be far away when your Gmail may have a quantum key.

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Is time travel allowed by the laws of physics?

Is time travel allowed by the laws of physics? | Amazing Science |

Albert Einstein's relativistic laws of physics tell us that passing of time is "relative". If you and I move differently or are at different locations in a gravitational field, then the rate of flow of time that you experience (the rate that governs the ticking of any very good clock you carry with you and that governs the aging of your body) is different from the rate of time flow that I experience.

This personal character of time allows one person to travel forward in time much faster than another, a phenomenon embodied in the so-called twins paradox. One twin (call him Methuselah) stays at home on Earth, the other (Florence) travels out into the Universe at high speed and then returns. When they meet at the end of the trip, Florence will have aged far less than Methuselah; for example, Florence may have aged 30 years and Methuselah 4,500 years. The twin that ages least is the one who undergoes huge accelerations, to get up to high speed, slow down, reverse direction, then accelerate back and slow to a halt on Earth. The twin who leads the sedate life ages the most.

A massive black hole is another vehicle for rapid forward time travel: If Methuselah remains in orbit high above the event horizon of a massive black hole (say, one whose gravitational pull is that of a billion suns) and Florence travels down to near the event horizon and hovers just above it for, say, 30 years and then returns, Methuselah can have aged thousands or millions of years. This is because time flows much more slowly near a black hole's event horizon (where the acceleration of gravity is huge) than far above it (where one can live sedately). These time travel phenomena have been tested in the laboratory. Muons — short-lived elementary particles — travelling around and around in a storage ring at 0.9994 of the speed of light, at the Brookhaven National Laboratory on Long Island, New York, have been seen to age 29 times more slowly than muons at rest in the laboratory. And atomic clocks on the surface of the Earth have been seen to run more slowly than atomic clocks high above the Earth's surface — more slowly by about 4 parts in 10 billion.

Physicists have been working hard since the late 1980s to understand whether the laws of physics allow backward time travel. We do not have a definitive answer yet, but the likely answer has been summarised by Stephen Hawking, in his Chronology Protection Conjecture (see [1]): The laws of physics always conspire to prevent anything from travelling backward in time, thereby keeping the Universe safe for historians.

Two mechanisms might protect chronology: (1) Exotic material that is required for manufacturing of any time machine might be forbidden to exist — by the laws of physics. (2) Time machines might always self-destruct, explosively, when one tries to activate them. These mechanisms (1) and (2) are descriptive translations of mathematical results that we physicists have derived using the laws of physics expressed in their own natural language: mathematics. The sentences (1) and (2) capture the essence of our calculations, but crucial details are lost in translation. For anyone who wishes to struggle to understand those details, good places to start are a recent beautiful but highly technical review article by John Friedman (see [2]), and a much less technical but older and slightly outdated article by Matt Visser (see [3]).

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Nuclear power and nuclear weapons: what's the difference?

Nuclear power and nuclear weapons: what's the difference? | Amazing Science |
It is the received wisdom that nuclear weapons and nuclear power are inseparable. Consequently, any country that builds a civilian nuclear power station is able to build an atomic bomb within a couple of years.

Clearly there are overlaps in knowledge and technology between the civil and military nuclear industries. There are five declared and four other nuclear-armed countries (assuming Israel's warheads detonate). There are 31 nations with nuclear power stations and 58 with research reactors. Only seven of the nine nuclear-armed countries have civilian power programs.

All of the technical factors can be circumvented with sufficient time and money. Uneconomic fuel cycles can be run and warheads built with high levels of radioactivity. However, no country has developed indigenous nuclear weapons after deploying civilian nuclear power stations. Historically, if a country wants to produce a nuclear bomb, they build reactors especially for the job of making plutonium, and ignore civilian power stations.

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Graphene Effectively Filters Electrons According to the Direction of Their Spin

Graphene Effectively Filters Electrons According to the Direction of Their Spin | Amazing Science |
New research from MIT shows that graphene can effectively filter electrons according to the direction of their spin, something that cannot be done by any conventional electronic system.

Graphene has become an all-purpose wonder material, spurring armies of researchers to explore new possibilities for this two-dimensional lattice of pure carbon. But new research at MIT has found additional potential for the material by uncovering unexpected features that show up under some extreme conditions — features that could render graphene suitable for exotic uses such as quantum computing.

The research is published in Nature in a paper by professors Pablo Jarillo-Herrero and Ray Ashoori, postdocs Andrea Young and Ben Hunt, graduate student Javier Sanchez-Yamaguchi, and three others. Under an extremely powerful magnetic field and at extremely low temperature, the researchers found, graphene can effectively filter electrons according to the direction of their spin, something that cannot be done by any conventional electronic system.

Under typical conditions, sheets of graphene behave as normal conductors: Apply a voltage, and current flows throughout the two-dimensional flake. If you turn on a magnetic field perpendicular to the graphene flake, however, the behavior changes: Current flows only along the edge, while the bulk remains insulating. Moreover, this current flows only in one direction — clockwise or counterclockwise, depending on the orientation of the magnetic field — in a phenomenon known as the quantum Hall effect.

In the new work, the researchers found that if they applied a second powerful magnetic field — this time in the same plane as the graphene flake — the material’s behavior changes yet again: Electrons can move around the conducting edge in either direction, with electrons that have one kind of spin moving clockwise while those with the opposite spin move counterclockwise.

“We created an unusual kind of conductor along the edge,” says Young, a Pappalardo Postdoctoral Fellow in MIT’s physics department and the paper’s lead author, “virtually a one-dimensional wire.” The segregation of electrons according to spin is “a normal feature of topological insulators,” he says, “but graphene is not normally a topological insulator. We’re getting the same effect in a very different material system.”

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Method for mass production of graphene-based field-effect transistors (FETs) developed

Method for mass production of graphene-based field-effect transistors (FETs) developed | Amazing Science |

Ulsan National Institute of Science and Technology(UNIST) researchers in Korea have announced a method for mass production of graphene-based field-effect transistors (FETs).

The design creates boron/nitrogen co-doped graphene nanoplatelets (BCN-graphene) via a simple solvothermalreaction of BBr3/CCl4/N2 in the presence of potassium.

Various methods of making graphene-based FETs have been exploited, including doping graphene, tailoring graphene like a nanoribbon, and using boron nitride as a support, the researchers said. Among the methods of controlling the bandgap* of graphene, doping methods show the most promise in terms of industrial-scale feasibility, they suggest.

Researchers have previously tried to add boron to graphene to open its bandgap to achieve semiconductor performance, without success, because the atomic size of boron, 85 pm (atomic radius) is larger than that of carbon (77 pm).

Now, the UNIST researcher team, led by Prof. Jong-Beom Baek, has found that boron/nitrogen co-doping is only feasible when carbon tetrachloride (CCl4 ) is treated with boron tribromide (BBr3 ) and nitrogen (N2) gas, which at 70 pm is a bit smaller than carbon and boron.

Pairing two nitrogen atoms and two boron atoms can compensate for the atomic size mismatch, so boron and nitrogen pairs can be easily introduced into the graphitic network, the researchers say. The resultant BCN-graphene generates a bandgap appropriate for FETs.

“Although the performance of the FET is not in the range of commercial silicon-based semiconductors, this initiative work should be the proof of a new concept and a great leap forward for studying graphene with bandgap opening,” said Baek. “Now, the remaining challenge is fine-tuning a bandgap to improve the on/off current ratio for real device applications.”

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Massive galaxy cluster verifies kinetic Sunyaev-Zel'dovich effect

Massive galaxy cluster verifies kinetic Sunyaev-Zel'dovich effect | Amazing Science |

By observing a high-speed component of a massive galaxy cluster, Caltech/JPL scientists and collaborators have detected for the first time in an individual object the kinetic Sunyaev-Zel'dovich effect, a change in the cosmic microwave background caused by its interaction with massive moving objects.

MACS J0717.5+3745 is an extraordinarily dynamic galaxy cluster with a total mass greater than 1015 (a million billion) times the mass of the sun or more than 1,000 times the mass of our own galaxy. It appears to contain three relatively stationary subclusters (A, C, and D) and one subcluster (B) that is being drawn into the larger galaxy cluster, moving at a speed of 3,000 kilometers per second.

The galaxy cluster was observed by a team led by Sunil Golwala, professor of physics at Caltech and director of the Caltech Submillimeter Observatory (CSO) in Hawaii. Subcluster B was observed during what appears to be its first fall into MACS J0717.5+3745. Its momentum will carry it through the center of the galaxy cluster temporarily, but the strong gravitational pull of MACS J0717.5+3745 will pull subcluster B back again. Eventually, subcluster B should settle in with its stationary counterparts, subclusters A, C, and D.

Though subcluster B's behavior is dramatic, it fits neatly within the standard cosmological model. But the details of the observations of MACS J0717.5+3745 at different wavelengths were puzzling until they were analyzed in terms of a theory called the kinetic Sunyaev-Zel'dovich (SZ) effect.

In 1972, two Russian physicists, Rashid Sunyaev and Yakov Zel'dovich, predicted that we should be able to see distortions in the cosmic microwave background (CMB)—the afterglow of the Big Bang—whenever it interacts with a collection of free electrons. These free electrons are present in the intracluster medium, which is made up primarily of gas. Gas within dense clusters of galaxies is heated to such an extreme temperature, around 100 million degrees, that it no longer coheres into atoms. According to Sunyaev and Zel'dovich, the photons of the CMB should be scattered by the high-energy electrons in the intracluster medium and take on a measurable energy boost as they pass through the galaxy cluster.

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Simulations back up theory that Universe is a hologram

Simulations back up theory that Universe is a hologram | Amazing Science |
A ten-dimensional theory of gravity makes the same predictions as standard quantum physics in fewer dimensions.

At a black hole, Albert Einstein's theory of gravity apparently clashes with quantum physics, but that conflict could be solved if the Universe were a holographic projection. A team of physicists has provided some of the clearest evidence yet that our Universe could be just one big projection. 

In 1997, theoretical physicist Juan Maldacena proposed1 that an audacious model of the Universe in which gravity arises from infinitesimally thin, vibrating strings could be reinterpreted in terms of well-established physics. The mathematically intricate world of strings, which exist in nine dimensions of space plus one of time, would be merely a hologram: the real action would play out in a simpler, flatter cosmos where there is no gravity.

Maldacena's idea thrilled physicists because it offered a way to put the popular but still unproven theory of strings on solid footing — and because it solved apparent inconsistencies between quantum physics and Einstein's theory of gravity. It provided physicists with a mathematical Rosetta stone, a 'duality', that allowed them to translate back and forth between the two languages, and solve problems in one model that seemed intractable in the other and vice versa. But although the validity of Maldacena's ideas has pretty much been taken for granted ever since, a rigorous proof has been elusive.

In two papers posted on the arXiv repository, Yoshifumi Hyakutake of Ibaraki University in Japan and his colleagues now provide, if not an actual proof, at least compelling evidence that Maldacena’s conjecture is true. In one paper2, Hyakutake computes the internal energy of a black hole, the position of its event horizon (the boundary between the black hole and the rest of the Universe), its entropy and other properties based on the predictions of string theory as well as the effects of so-called virtual particles that continuously pop into and out of existence. In the other3, he and his collaborators calculate the internal energy of the corresponding lower-dimensional cosmos with no gravity. The two computer calculations match. “It seems to be a correct computation,” says Maldacena, who is now at the Institute for Advanced Study in Princeton, New Jersey and who did not contribute to the team's work.

The findings “are an interesting way to test many ideas in quantum gravity and string theory”, Maldacena adds. The two papers, he notes, are the culmination of a series of articles contributed by the Japanese team over the past few years. “The whole sequence of papers is very nice because it tests the dual [nature of the universes] in regimes where there are no analytic tests.”

“They have numerically confirmed, perhaps for the first time, something we were fairly sure had to be true, but was still a conjecture — namely that the thermodynamics of certain black holes can be reproduced from a lower-dimensional universe,” says Leonard Susskind, a theoretical physicist at Stanford University in California who was among the first theoreticians to explore the idea of holographic universes.

Neither of the model universes explored by the Japanese team resembles our own, Maldacena notes. The cosmos with a black hole has ten dimensions, with eight of them forming an eight-dimensional sphere. The lower-dimensional, gravity-free one has but a single dimension, and its menagerie of quantum particles resembles a group of idealized springs, or harmonic oscillators, attached to one another.

Nevertheless, says Maldacena, the numerical proof that these two seemingly disparate worlds are actually identical gives hope that the gravitational properties of our Universe can one day be explained by a simpler cosmos purely in terms of quantum theory.


  1. Hyakutake, Y. (2013).

  2. Hanada, M., Hyakutake, Y., Ishiki, G. & Nishimura, J. (2013).

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CERN experiment produces first beam of antihydrogen atoms for hyperfine study

CERN experiment produces first beam of antihydrogen atoms for hyperfine study | Amazing Science |

The ASACUSA experiment at CERN has succeeded for the first time in producing a beam of antihydrogen atoms. In a paper published today in Nature Communications, the ASACUSA collaboration reports the unambiguous detection of 80 antihydrogen atoms 2.7 metres downstream of their production, where the perturbing influence of the magnetic fields used initially to produce the antiatoms is small. This result is a significant step towards precise hyperfine spectroscopy of antihydrogen atoms.

Primordial antimatter has so far never been observed in the Universe, and its absence remains a major scientific enigma. Nevertheless, it is possible to produce significant amounts of antihydrogen in experiments at CERN by mixing antielectrons (positrons) and low energy antiprotons produced by the Antiproton Decelerator.

The spectra of hydrogen and antihydrogen are predicted to be identical, so any tiny difference between them would immediately open a window to new physics, and could help in solving the antimatter mystery. With its single proton accompanied by just one electron, hydrogen is the simplest existing atom, and one of the most precisely investigated and best understood systems in modern physics. Thus comparisons of hydrogen and antihydrogen atoms constitute one of the best ways to perform highly precise tests of matter/antimatter symmetry.

Matter and antimatter annihilate immediately when they meet, so aside from creating antihydrogen, one of the key challenges for physicists is to keep antiatoms away from ordinary matter. To do so, experiments take advantage of antihydrogen's magnetic properties (which are similar to hydrogen's) and use very strong non-uniform magnetic fields to trap antiatoms long enough to study them. However, the strong magnetic field gradients degrade the spectroscopic properties of the (anti)atoms. To allow for clean high-resolution spectroscopy, the ASACUSA collaboration developed an innovative set-up to transfer antihydrogen atoms to a region where they can be studied in flight, far from the strong magnetic field.

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Acoustic lens generates tunable 'sound bullets' for ultrasound applications

Acoustic lens generates tunable 'sound bullets' for ultrasound applications | Amazing Science |

Scientists have developed an acoustic lens that produces pressure pulses that are so intense they're called "sound bullets." Although they are too high-pitched to be audible to the human ear, the sound bullets could have a variety of uses such as in medical ultrasound, underwater mapping, and other high-intensity acoustic applications.

An acoustic lens that could generate sound bullets was first demonstrated in 2009 by Professor Chiara Daraio and postdoctoral researcher Alessandro Spadoni at the California Institute of Technology in Pasadena, California. In that study, the researchers developed a 1D array of stainless steel spheres that struck each other similar to the way in which the metal balls in a Newton's Cradle toy strike each other. An impact at one end of the chain of spheres generates solitary waves whose speed and focal points can be controlled by controlling the properties of the device.

Now in a recent paper published in Applied Physics Letters, Daraio and a new team of researchers have expanded this 1D acoustic lens into a 2D version consisting of 13 vertical chains of 30 stainless steel spheres arranged in a square lattice. In addition, they experimentally demonstrated the ability to create sound bullets in water, which moves the technology a step closer to biomedical and naval applications. A 2D acoustic lens has two main advantages over the 1D version: the ability to control the focus in three dimensions and the potential for larger pressure gains due to the more compact arrangement.

"This work was started to move a step closer to applications," Daraio told "A 2D array of 'acoustic sources' (i.e., chains of particles) allow us to focus the 'sound bullets' in 3D, creating a more compact and controllable acoustic signal. This focused pressure field can then be moved (or even scanned) in a 3D volume. This is a very desirable feature in acoustic imaging and surgery, for example. Most importantly, we demonstrated the ability to produce sound bullets in water, which was something we had predicted earlier with numerical simulations, but that was never validated experimentally. Given that most acoustic imaging methods are used in a water setting (think sonars, or ultrasonic images of the human body), this is a big step forward towards a practical implementation."

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For the first time, astronomers discover a black hole orbiting a spinning star

For the first time, astronomers discover a black hole orbiting a spinning star | Amazing Science |
There's a star about 8,500 light-years away that's spinning so fast its surface speed exceeds 620,000 mph. Astronomers are familiar with these kinds of stars, but this one's wholly unique in that it has a rather strange companion: a black hole.

To date, astronomers have catalogued more than 80 of these Be type stars. They're typically members of a binary system, with the companion being a neutron star (collapsed stars that aren't big enough to form black holes). Amazingly, Be stars can spin at these horrendous speeds without breaking-up, producing huge centrifugal forces. The Be star in question, MWC 656, was first discovered in 2010. But Spanish researchers now say there's a black hole spinning around it.

A detailed analysis of its spectrum allowed scientists to infer the characteristics of its companion. "It turned out to be an object with a mass between 3.8 and 6.9 solar masses," said Ignasi Ribas of CSIC at the Institute of Space Sciences. "An object like that, invisible to telescopes and with such large mass, can only be a black hole because no neutron star with more than three solar masses can exist."

The black hole orbits the more massive Be star and is fed by matter ejected from the latter. "The high rotation speed of the Be star causes matter to be ejected into an equatorial disk," said Ignacio Negueruela at the University of Alicante. "This matter is attracted by the black hole and falls on to it, forming another disk, called an accretion disk. By studying the emission from the accretion disk, we could analyze the motion of the black hole and measure its mass."

The astronomers think it's a member of a hidden population of Be stars paired with black holes and that they're more common than previous thought. Unfortunately, they're hard to detect because their black holes are fed from gas ejected by the Be stars without producing much radiation.


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Quantum mechanics explains efficiency of photosynthesis

Quantum mechanics explains efficiency of photosynthesis | Amazing Science |

Light-gathering macromolecules in plant cells transfer energy by taking advantage of molecular vibrations whose physical descriptions have no equivalents in classical physics, according to the first unambiguous theoretical evidence of quantum effects in photosynthesis published today in the journal Nature CommunicationsScientists have observed previously the quantum character of light transport through the molecular machines at work in natural photosynthesis.

The majority of light-gathering macromolecules are composed of chromophores (responsible for the colour of molecules) attached to proteins, which carry out the first step of photosynthesis, capturing sunlight and transferring the associated energy highly efficiently. Previous experiments suggest that energy is transferred in a wave-like manner, exploiting quantum phenomena, but crucially, a non-classical explanation could not be conclusively proved as the phenomena identified could equally be described using classical physics.

Often, to observe or exploit quantum mechanical phenomena systems need to be cooled to very low temperatures. This however does not seem to be the case in some biological systems, which display quantum properties even at ambient temperatures.

Now, a team at UCL have attempted to identify features in these biological systems which can only be predicted by quantum physics, and for which no classical analogues exist.

"Energy transfer in light-harvesting macromolecules is assisted by specific vibrational motions of the chromophores," said Alexandra Olaya-Castro (UCL Physics & Astronomy), supervisor and co-author of the research. "We found that the properties of some of the chromophore vibrations that assist energy transfer during photosynthesis can never be described with classical laws, and moreover, this non-classical behaviour enhances the efficiency of the energy transfer."

Molecular vibrations are periodic motions of the atoms in a molecule, like the motion of a mass attached to a spring. When the energy of a collective vibration of two chromphores matches the energy difference between the electronic transitions of these chromophores a resonance occurs and efficient energy exchange between electronic and vibrational degrees of freedom takes place.

Providing that the energy associated to the vibration is higher than the temperature scale, only a discrete unit or quantum of energy is exchanged. Consequently, as energy is transferred from one chromophore to the other, the collective vibration displays properties that have no classical counterpart.

The UCL team found the unambiguous signature of non-classicality is given by a negative joint probability of finding the chromophores with certain relative positions and momenta. In classical physics, probability distributions are always positive.

"The negative values in these probability distributions are a manifestation of a truly quantum feature, that is, the coherent exchange of a single quantum of energy," explained Edward O'Reilly (UCL Physics & Astronomy), first author of the study. "When this happens electronic and vibrational degrees of freedom are jointly and transiently in a superposition of quantum states, a feature that can never be predicted with classical physics."

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Cloning quantum information from the past

Cloning quantum information from the past | Amazing Science |

It is theoretically possible for time travelers to copy quantum data from the past, according to three scientists in a recent paper in Physical Review LettersIt all started when David Deutsch, a pioneer of quantum computing and a physicist at Oxford, came up with a simplified model of time travel to deal with the Grandfather paradox*.  He solved the paradox originally using a slight change to quantum theory, proposing that you could change the past as long as you did so in a self-consistent manner.

“Meaning that, if you kill your grandfather, you do it with only probability one-half,” said PRL co-author Mark Wilde, an LSU assistant professor with a joint appointment in the Department of Physics and Astronomy and with the Center for Computation and Technology. “Then, he’s dead with probability one-half, and you are not born with probability one-half, but the opposite is a fair chance. You could have existed with probability one-half to go back and kill your grandfather.”

No-cloning theorem

But the Grandfather paradox is not the only complication with time travel. Another problem is the “no-cloning theorem,” or the no “subatomic Xerox-machine” theorem, known since 1982. This theorem, which is related to the fact that one cannot copy quantum data at will, is a consequence of Heisenberg’s  Uncertainty Principle, by which one can measure either the position of a particle or its momentum, but not both with unlimited accuracy.

According to the Uncertainty Principle, it is thus impossible to have a subatomic Xerox-machine that would take one particle and spit out two particles with the same position and momentum — because then you would know too much about both particles at once.

“We can always look at a paper, and then copy the words on it. That’s what we call copying classical data,” Wilde said. “But you can’t arbitrarily copy quantum data, unless it takes the special form of classical data. This no-cloning theorem is a fundamental part of quantum mechanics — it helps us reason how to process quantum data. If you can’t copy data, then you have to think of everything in a very different way.”

Consequences of being able to copy quantum data from the past

But whether or not the no-cloning theorem can truly be violated as Wilde’s new approach suggests, the consequences of being able to copy quantum data from the past are significant. Systems for secure Internet communications, for example, will likely soon rely on quantum security protocols that could be broken or “hacked” if Wilde’s looping time travel methods were correct.

“If an adversary, if a malicious person, were to have access to these time loops, then they could break the security of quantum key distribution,” Wilde said. “That’s one way of interpreting it. But it’s a very strong practical implication because the big push of quantum communication is this secure way of communicating. We believe that this is the strongest form of encryption that is out there because it’s based on physical principles.”

Physicists and computer scientists are working on securing critical and sensitive communications using the principles of quantum mechanics. Such encryption is believed to be unbreakable — that is, as long as hackers don’t have access to Wilde’s looping closed timelike curves.

“This ability to copy quantum information freely would turn quantum theory into an effectively classical theory in which, for example, classical data thought to be secured by quantum cryptography would no longer be safe,” Wilde said. “It seems like there should be a revision to Deutsch’s model which would simultaneously resolve the various time travel paradoxes but not lead to such striking consequences for quantum information processing. However, no one yet has offered a model that meets these two requirements. This is the subject of open research.”

* In the Grandfather paradox, a time traveler faces the problem that if he kills his grandfather back in time, then he himself is never born, and consequently is unable to travel through time to kill his grandfather, and so on. Some theorists have used this paradox to argue that it is actually impossible to change the past. The question is, how would you have existed in the first place to go back in time and kill your grandfather?”

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It’s a Good Time for Time-Bin Qubits

It’s a Good Time for Time-Bin Qubits | Amazing Science |
Qubits encoded in time advance the prospects for quantum computing with single photons.

In contrast to classical bits of information that are either 0 or 1, quantum bits—or “qubits”—can be in superposition states of 0 and 1. Just like classical bits, however, qubits are physical objects that have to be implemented in real physical systems. Researchers have used single photons as physical qubits, with the quantum information encoded in terms of polarization, angular momentum, and many other degrees of freedom. The time-bin degree of freedom (that is, encoding quantum information in terms of relative arrival times of light pulses) offers a particularly robust kind of single-photon qubits, and two recent papers have advanced the use of time-bin qubits in dramatic ways.

Writing in Physical Review Letters, Peter Humphreys and colleagues at the University of Oxford, UK, have developed a technique for optical quantum computing using time-bin qubits [1]. In principle, their concept allows photonic quantum computing using a single optical path (or fiber) rather than a maze of multiple paths, thereby drastically reducing the overall complexity of these kinds of systems. Also inPhysical Review Letters, John Donohue and colleagues at the Institute for Quantum Computing, University of Waterloo, Canada, have demonstrated an ultrafast measurement technique for time-bin qubits that could enable higher data rates and fewer errors in photonic systems [2]. These two developments represent a huge step towards the realization of practical quantum information processing devices using single-photon qubits.

Time-bin qubits were originally developed by a group at the University of Geneva, Switzerland [3]. To understand the basic form of these qubits,

consider a single-photon wave packet passing through a two-path Mach-Zehnder interferometer: if the two paths have different lengths, the photon wave packet will exit the interferometer in a quantum-mechanical superposition of an “early time bin” and “later time bin.” By adjusting the parameters of the interferometer to control relative phase and amplitude, one can accurately produce arbitrary time-bin qubits. The Geneva group famously showed that these time-bin qubits could propagate over long distances in optical fibers with very little decoherence, allowing much more robust quantum communication systems than those based on polarization-encoded qubits [45].

Extending these ideas from the realm of quantum communication, Humphreys et al. have now shown that it is possible to use time-bin qubits for quantum computing [1]. Their approach is based on the well-known linear optics quantum computing (LOQC) paradigm that uses large numbers of ancilla photons and measurement-based nonlinearities to realize near-deterministic quantum logic gates [6]. Previous work on the LOQC approach has primarily been based on polarization qubits and spatial modes that can quickly escalate into extremely unwieldy nested interferometers with very large numbers of paths that need to be stabilized to subwavelength precision [678]. In contrast, Humphreys et al. have now shown that the use of time-bin qubits enables the LOQC approach in a single spatial mode, offering the possibility of far less experimental complexity and a potential for reduced decoherence mechanisms.

As shown in the figure above, their approach involves a large string of time-bin qubits propagating along a single waveguide (such as an optical fiber), with the available polarization degree of freedom used to define a “register” mode for propagation and storage, and a “processing” mode for qubit manipulations. As the qubits propagate along the waveguide, Humphreys et al. pull out various time bins from the register mode, process them with phase shifts, bit flips, and couplings, and then return them to the register mode in a coherent way. The authors used these ideas to propose the full suite of single-qubit operations and two-qubit entangling gates needed for universal quantum computation. The validity of their basic method was demonstrated in a very convincing experiment that used single-photon qubits and linear optical elements for time-bin creation and manipulation [1].

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Triple star system might reveal secrets of gravity

Triple star system might reveal secrets of gravity | Amazing Science |

Astronomers have discovered a unique triple star system which could reveal the true nature of gravity. They found a pulsar with two white dwarfs all packed in a space smaller than Earth's orbit of the Sun.

The trio's unusually close orbits allow precise measurements of gravity and could resolve difficulties with Einstein's theories. The results appear in Nature journal and will be presented at the 223rd American Astronomical Society meeting.

"This triple system gives us a natural cosmic laboratory far better than anything found before for learning exactly how such three-body systems work and potentially for detecting problems with general relativity that physicists expect to see under extreme conditions," said Scott Ransom of the US National Radio Astronomy Observatory (NRAO) in Charlottesville, VA.

"This is a fascinating system in many ways, including what must have been a completely crazy formation history, and we have much work to do to fully understand it."

Pulsars emit lighthouse-like beams of radio waves that rapidly sweep through space as the stars spin on their axes. They are formed after a supernova collapses a burnt-out star to a dense, highly magnetised ball of neutrons. Using the Green Bank Telescope, the astronomers discovered a pulsar 4,200 light-years from Earth, spinning nearly 366 times per second.

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Midair levitation of objects using sound waves

The essence of levitation technology is the countervailing of gravity. It is known that an ultrasound standing wave is capable of suspending small particles at its sound pressure nodes and, so far, this method has been used to levitate lightweight particles, small creatures, and water droplets.
The acoustic axis of the ultrasound beam in these previous studies was parallel to the gravitational force, and the levitated objects were manipulated along the fixed axis (i.e. one-dimensionally) by controlling the phases or frequencies of bolted Langevin-type transducers. In the present study, we considered extended acoustic manipulation whereby millimetre-sized particles were levitated and moved three-dimensionally by localised ultrasonic standing waves, which were generated by ultrasonic phased arrays. Our manipulation system has two original features. One is the direction of the ultrasound beam, which is arbitrary because the force acting toward its centre is also utilised. The other is the manipulation principle by which a localised standing wave is generated at an arbitrary position and moved three-dimensionally by opposed and ultrasonic phased arrays. We experimentally confirmed that various materials could be manipulated by our proposed method.

Yoichi Ochiai, Takayuki Hoshi, Jun Rekimoto: Three-dimensional Mid-air Acoustic Manipulation by Ultrasonic Phased Arrays arXiv:1312.4006

Yoichi Ochiai (The University of Tokyo)
Takayuki Hoshi (Nagoya Institute of Technology)
Jun Rekimoto (The University of Tokyo / Sony CSL) 

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Sharing Entanglement without Sending It

Sharing Entanglement without Sending It | Amazing Science |

To challenge the limited understanding of the then-young quantum theory, Einstein, Podolsky, and Rosen constructed, in 1935, their EPR Gedankenexperiment, in which they introduced entangled states that exhibit strange correlations over macroscopic distances. By now we have learned that entangled states are an element of physical reality. They lie at the heart of quantum physics and can, in fact, be used as a powerful resource in emerging quantum technologies. Yet we find out in amazement that we have still not completely captured the full scope of the fascinating nature of entanglement.

Three different international groups have now reported in Physical Review Letters experiments of distributing entanglement between two distant parties by sending a nonentangled carrier. These arrangements instead place the carrier in a “cheaper,” so-called separable state, which exhibit correlations that can be established remotely between separated parties.

Entanglement is typically characterized by anomalously strong correlations between presently noninteracting parties, typically called Alice and Bob, which have normally interacted in the past. A common setup uses a nonlinear crystal to create an entangled pair of orthogonally polarized photons that are then sent separately, one to Alice and the other to Bob. In the field of quantum information science, the remote establishment of entanglement is key for most applications because it introduces purely nonclassical correlations and the counterintuitive nature of quantum physics. It enables such remarkable tasks as quantum teleportation, efficient quantum communication, fundamental tests of quantum physics, and long-distance quantum cryptography.

  1. A. Einstein, B. Podolsky, and N. Rosen, “Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?” Phys. Rev. 47, 777 (1935).
  2. A. Fedrizzi, M. Zuppardo, G. G. Gillett, M. A. Broome, M. P. Almeida, M. Paternostro, A. G. White, and T. Paterek, “Experimental Distribution of Entanglement with Separable Carriers,” Phys. Rev. Lett. 111, 230504 (2013).
  3. C. Peuntinger, V. Chille, L. Mišta, N. Korolkova, M. Förtsch, J. Korger, C. Marquardt, and G. Leuchs, “Distributing Entanglement with Separable States,” Phys. Rev. Lett. 111, 230506 (2013).
  4. C. E. Vollmer, D. Schulze, T. Eberle, V. Händchen, J. Fiurášek, and R. Schnabel, “Experimental Entanglement Distribution by Separable States,” Phys. Rev. Lett. 111, 230505 (2013).
  5. R. F. Werner, “Quantum States with Einstein-Podolsky-Rosen Correlations Admitting a Hidden-Variable Model,” Phys. Rev. A 40, 4277 (1989).
  6. C. H. Bennett, D. P. DiVincenzo, J. A. Smolin, and W. K. Wootters, “Mixed-state Entanglement And Quantum Error Correction,” Phys. Rev. A 54, 3824 (1996).
  7. T. S. Cubitt, F. Verstraete, W. Dür, and J. I. Cirac, “Separable States Can Be Used To Distribute Entanglement,” Phys. Rev. Lett. 91, 037902 (2003).
  8. A. Steltsov, H. Kampermann, and D. Bruß, “Quantum Cost for Sending Entanglement,” Phys. Rev. Lett. 108, 250501 (2012).
  9. T. K. Chuan, J. Maillard, K. Modi, T. Paterek, M. Paternostro, and M. Piani, “Quantum Discord Bounds the Amount of Distributed Entanglement,” Phys. Rev. Lett. 109, 070501 (2012).
  10. L. Mišta, Jr. and N. Korolkova, “Distribution of Continuous-Variable Entanglement by Separable Gaussian States,” Phys. Rev A 77, 050302 (2008).

Via Alin Velea, Ben van Lier
Miro Svetlik's curator insight, January 4, 2014 6:32 AM

Again a step closer to Quantum Cryptography. It is a time that we will see the commercial implementation of quantum encryption. It will also have quite an impact on Digital currencies which are based on current cryptography. We are living in brave new world.

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Chasing the Higgs: How 2 Teams of Rivals Searched for Physics’ Most Elusive Particle

Chasing the Higgs: How 2 Teams of Rivals Searched for Physics’ Most Elusive Particle | Amazing Science |
At the Large Hadron Collider near Geneva, two armies of physicists struggled to close in on the Higgs boson, the Great White Whale of modern science.

Last year, the discovery of the particle credited with giving others mass was cheerfully announced to a packed and jubilant auditorium at CERN near Geneva, Switzerland. The moment marked the end of a 50-year hunt. But although the boson has been found, there is still plenty we do not know about the celebrated particle.

When the particle's discovery was announced, researchers working with the Large Hadron Collider (LHC) at CERN resisted calling their quarry the Higgs boson outright, preferring the vaguer "Higgs-like boson", or "particle resembling the Higgs". They knew the particle they had glimpsed was a brand new boson, one of two types of elementary particle. But it was not clear if its properties corresponded exactly to those laid out for the Higgs in the standard model of particle physics, which describes all known particles and the forces acting on them.

In fact, many physicists were hoping the boson would prove to be something more exotic, because this would suggest ways to extend the standard model, which currently cannot explain dark matter or gravity, for example.

A year on, key properties known as spin and parity, as well as the exact particles the boson decays into, are gradually being pinned down, and the boson seems to be behaving as expected, leading to the award of official Higgs status in March. "We have made enough property measurements to start to convince ourselves that what we are looking at is a Higgs boson," says Oliver Buchmueller of Imperial College London, a member of the LHC's CMS collaboration, one of the two teams that announced evidence for the Higgs.

But even though it fulfils the minimum requirements of a Higgs boson, that doesn't mean it is vanilla, says Buchmueller. "The precision with which we are measuring these properties today is not sufficient to say whether this is the minimal realisation of the Higgs mechanism – or something more." One mystery that remains is why the Higgs boson decays into more photons than expected. This excess was initially reported last July. In the latest analyses, ATLAS still sees the Higgs decaying into too many photons, while in data collected by CMS there is no excess.

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Beam of darkness makes objects invisible from a distance

Beam of darkness makes objects invisible from a distance | Amazing Science |

A research team from the University of Singapore has developed a device that can make objects invisible by bathing them in a beam of darkness.

The system takes the conventional approach to optics -- which generally aims to make images as sharp and clear as possible -- and turns it completely on its head. Usually imaging systems focus light into a pattern known as a point spreading function, which consists of a spiked central region of high intensity (the main lobe) surrounded by a concentric region of lower intensity light and a higher intensity lobe after this. In order to achieve the best resolution, the central region should be narrowed and intensified, while the outer lobe is supressed. This makes sure that the image is very bright and sharp with well-defined edges.

The researchers' beam can hide macroscopic objects by taking the opposite approach: intensifying the outer lobes suppressing the central region. This means that the central region has a field intensity of light that is pretty much zero. They did this using special lenses that could smear out the central spike while increasing the intensity of the concentric lobes. Objects in this 3D region cannot be resolved and so are hidden from sight. The effect has been named "anti-resolution".

The research team managed to hide a three-dimensional object (the letter N) that was 40-micrometers in size from a single frequency of light (red laser light). "This new scheme of manoeuvring light creates a plethora of possibilities for optical imaging systems, superb surveillance by seeing things behind for the military use, or cloaking the object surrounded by high field intensity," explains lead author Chao Wan, from the Department of Electrical and Computer Engineering at the National University of Singapore.

The technology could one day pave the way for a sort of "invisibility gun" that could be aimed at an object. In order to do this, the researchers would have to extend the effect to the wider spectrum of light.

You can read the full study online.

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World's First Macroscopic Invisibility Cloak Based On Ordinary Calcite

World's First Macroscopic Invisibility Cloak Based On Ordinary Calcite | Amazing Science |

Baile Zhang, an assistant professor of physics at Nanyang Technological University in Singapore, has used the light-bending qualities of calcite - a cheap and abundant mineral that is a form of calcium carbonate - to create the first macroscopic invisibility cloak. Zhang originally came up with the technology in 2010. This short video clip is similar to what he recently demonstrated on stage at TED2013. He is placing a piece of calcite over a rolled-up Post-it note submerged in oil, making the pink tube appear to disappear. This research has applications in imaging, communication, and defense.

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