Amazing Science
770.7K views | +50 today
Follow
Amazing Science
Amazing science facts - 3D_printing • aging • AI • anthropology • art • astronomy • bigdata • bioinformatics • biology • biotech • chemistry • computers • cosmology • education • environment • evolution • future • genetics • genomics • geosciences • green_energy • history • language • map • material_science • math • med • medicine • microscopy • nanotech • neuroscience • paleontology • photography • photonics • physics • postings • robotics • science • technology • video
Your new post is loading...
Scooped by Dr. Stefan Gruenwald
Scoop.it!

D-Wave Systems Breaks the 1000 Qubit Quantum Computing Barrier

D-Wave Systems Breaks the 1000 Qubit Quantum Computing Barrier | Amazing Science | Scoop.it

New Milestone Will Enable System to Address Larger and More Complex Problems


D-Wave Systems Inc., the world's first quantum computing company, today announced that it has broken the 1000 qubit barrier, developing a processor about double the size of D-Wave’s previous generation and far exceeding the number of qubits ever developed by D-Wave or any other quantum effort.


This is a major technological and scientific achievement that will allow significantly more complex computational problems to be solved than was possible on any previous quantum computer.


D-Wave’s quantum computer runs a quantum annealing algorithm to find the lowest points, corresponding to optimal or near optimal solutions, in a virtual “energy landscape.” Every additional qubit doubles the search space of the processor. At 1000 qubits, the new processor considers 21000possibilities simultaneously, a search space which dwarfs the 2512 possibilities available to the 512-qubit D-Wave Two. ‪In fact, the new search space contains far more possibilities than there are ‪particles in the observable universe.


“For the high-performance computing industry, the promise of quantum computing is very exciting. It offers the potential to solve important problems that either can’t be solved today or would take an unreasonable amount of time to solve,” said Earl Joseph, IDC program vice president for HPC. “D-Wave is at the forefront of this space today with customers like NASA and Google, and this latest advancement will contribute significantly to the evolution of the Quantum Computing industry.”


As the only manufacturer of scalable quantum processors, D-Wave breaks new ground with every succeeding generation it develops. The new processors, comprising over 128,000 Josephson tunnel junctions, are believed to be the most complex superconductor integrated circuits ever successfully yielded. They are fabricated in part at D-Wave’s facilities in Palo Alto, CA and at Cypress Semiconductor’s wafer foundry located in Bloomington, Minnesota.


“Temperature, noise, and precision all play a profound role in how well quantum processors solve problems.  Beyond scaling up the technology by doubling the number of qubits, we also achieved key technology advances prioritized around their impact on performance,” said Jeremy Hilton, D-Wave vice president, processor development. “We expect to release benchmarking data that demonstrate new levels of performance later this year.”


The 1000-qubit milestone is the result of intensive research and development by D-Wave and reflects a triumph over a variety of design challenges aimed at enhancing performance and boosting solution quality. Beyond the much larger number of qubits, other significant innovations include:


  •  Lower Operating Temperature: While the previous generation processor ran at a temperature close to absolute zero, the new processor runs 40% colder. The lower operating temperature enhances the importance of quantum effects, which increases the ability to discriminate the best result from a collection of good candidates.
  • Reduced Noise: Through a combination of improved design, architectural enhancements and materials changes, noise levels have been reduced by 50% in comparison to the previous generation. The lower noise environment enhances problem-solving performance while boosting reliability and stability.
  • Increased Control Circuitry Precision: In the testing to date, the increased precision coupled with the noise reduction has demonstrated improved precision by up to 40%. To accomplish both while also improving manufacturing yield is a significant achievement.
  • Advanced Fabrication:  The new processors comprise over 128,000 Josephson junctions (tunnel junctions with superconducting electrodes) in a 6-metal layer planar process with 0.25μm features, believed to be the most complex superconductor integrated circuits ever built.
  • New Modes of Use: The new technology expands the boundaries of ways to exploit quantum resources.  In addition to performing discrete optimization like its predecessor, firmware and software upgrades will make it easier to use the system for sampling applications.
more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Physicists Create Microscope for Fermions

Physicists Create Microscope for Fermions | Amazing Science | Scoop.it

For the past twenty years, physicists have studied ultracold atomic gases of the two classes of particles: fermions (electrons, protons, neutrons, quarks, atoms) and bosons.


In 2009, physicists at Harvard University devised a microscope that successfully imaged individual bosons in a tightly spaced optical lattice.

The second boson microscope was created by scientists at the Max Planck Institute of Quantum Optics in Germany in 2010. These microscopes revealed, in unprecedented detail, the behavior of bosons under strong interactions. However, no one had yet developed a comparable microscope for fermions.


The new technique developed by Prof Martin Zwierlein and his colleagues at MIT uses two laser beams trained on a cloud of fermionic atoms in an optical lattice. The two beams, each of a different wavelength, cool the cloud, causing individual fermions to drop down an energy level, eventually bringing them to their lowest energy states – cool and stable enough to stay in place. At the same time, each fermion releases light, which is captured by the microscope and used to image the fermion’s exact position in the lattice – to an accuracy better than the wavelength of light.


With the new technique, Prof Zwierlein’s team was able to cool and image over 95% of the fermionic atoms making up a cloud of potassium gas. "An intriguing result from the technique appears to be that it can keep fermions cold even after imaging. That means I know where they are, and I can maybe move them around with a little tweezer to any location, and arrange them in any pattern I’d like,” said Prof Zwierlein, who is the senior author on the study published in the journal Physical Review Letters.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Quantum mechanical transport demonstrated for the first time in synthetic material at room temperature

Quantum mechanical transport demonstrated for the first time in synthetic material at room temperature | Amazing Science | Scoop.it
A diode a few atoms thick shows surprising quantum effect.

A quantum mechanical transport phenomenon demonstrated for the first time in synthetic, atomically-thin layered material at room temperature could lead to novel nanoelectronic circuits and devices, according to researchers at Penn State and three other U.S. and international universities.


The quantum transport effect, called negative differential resistance (NDR), was observed when a voltage was applied to structures made of one-atom-thick layers of several layered materials known as van der Waals materials. The three-part structures consist of a base of graphene followed by atomic layers of either molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2), or tungsten diselenide (WSe2).


NDR is a phenomenon in which the wave nature of electrons allows them to tunnel through any material with varying resistance. The potential of NDR lies in low voltage electronic circuits that could be operated at high frequency.


"Theory suggests that stacking two-dimensional layers of different materials one atop the other can lead to new materials with new phenomena," says Joshua Robinson, a Penn State assistant professor of materials science and engineering whose student, Yu-Chuan Lin, is first author on a paper appearing online today, June 19, in the journal Nature Communications. The paper is titled "Atomically Thin Resonant Tunnel Diodes Built from Synthetic van der Waals Heterostructures."


Achieving NDR in a resonant tunneling diode at room temperature requires nearly perfect interfaces, which are possible using direct growth techniques, in this case oxide vaporization of molybdenum oxide in the presence of sulfur vapor to make the MoS2 layer, and metal organic chemical vapor deposition to make the WSe2 and MoSe2.


"This is the first time these vertical heterostructures have been grown like this," Robinson says. "People typically use exfoliated materials that they stack, but it has been extremely difficult to see this phenomenon with exfoliated layers, because the interfaces are not clean. With direct growth we get pristine interfaces where we see this phenomenon every time."

What caught Lin and Robinson's attention was a sharp peak and valley in their electrical measurements where there would normally be a regular upward slope. Any unexpected phenomenon, if it is repeatable, is of interest, Robinson says. To explain their results, they consulted an expert in nanoscale electronic devices, Suman Datta, who told them they were seeing a 2D version of a resonant tunneling diode, a quantum mechanical device that operates at low power.


"Resonant tunnel diodes are important circuit components," says Datta, a coauthor on the paper and Penn State professor of electrical engineering. "Resonant tunneling diodes with NDR can be used to build high frequency oscillators. What this means is we have built the world's thinnest resonant tunneling diode, and it operates at room temperature!"

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Transient excitons observed in metals for the first time – the primary response of free electrons to light

Transient excitons observed in metals for the first time – the primary response of free electrons to light | Amazing Science | Scoop.it

Researchers have observed, in metals for the first time, transient excitons – the primary response of free electrons to light. Here, the researchers discovered that the surface electrons of silver crystals can maintain the excitonic state more than 100 times longer than for the bulk metal, enabling the excitons to be experimentally visualized by a newly developed multidimensional coherent spectroscopic technique.


Detecting excitons in metals could provide clues on how light is converted into electrical and chemical energy in solar cells and plants. This research may also provide ways to alter the function of metals in order to develop active elements for technologies such as optical communications by controlling how light is reflected from a metal.


The act of looking in a mirror is an everyday experience, but the quantum mechanical description behind this familiar phenomenon is still unknown. When light reflects from a mirror, the light “shakes” the metal’s free electrons and the resulting acceleration of electrons creates a nearly perfect replica of the incident light – providing a reflection. Excitons, or particles of the light-matter interaction where light photons become temporarily entangled with electrons in molecules and semiconductors, are known to be important to this process and others such as photosynthesis and optical communications.


Unfortunately, studying and proving how excitons function in metals is difficult because they are extremely short-lived, lasting for approximately 100 attoseconds, or less than a 0.1 quadrillionth of a second. For the first time researchers have observed excitons at metallic surfaces that maintain the excitonic state 100 times longer than in the bulk metal, enabling the excitons to be experimentally captured by a newly developed multidimensional multiphoton photoemission spectroscopic technique.


This discovery sheds light on the primary excitonic response of solids which could allow quantum control of electrons in metals, semiconductors, and organic materials. It also potentially allows for the generation of intense femotosecond electron pulses that could increase resolution for time-resolved electron microscopes that follow the motion of individual atoms and molecules as they rearrange themselves during structural transitions or chemical reactions.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

MIT Physicists Create Ultracold Gas of Na-K Alloy at 500 Nano Kelvin

MIT Physicists Create Ultracold Gas of Na-K Alloy at 500 Nano Kelvin | Amazing Science | Scoop.it

A team of physicists from MIT has successfully cooled molecules in a gas of sodium potassium (NaK) to a temperature of 500 nanokelvins, creating ultracold molecules.


The air around us is a chaotic superhighway of molecules whizzing through space and constantly colliding with each other at speeds of hundreds of miles per hour. Such erratic molecular behavior is normal at ambient temperatures.


But scientists have long suspected that if temperatures were to plunge to near absolute zero, molecules would come to a screeching halt, ceasing their individual chaotic motion and behaving as one collective body. This more orderly molecular behavior would begin to form very strange, exotic states of matter — states that have never been observed in the physical world.


Now experimental physicists at MIT have successfully cooled molecules in a gas of sodium potassium (NaK) to a temperature of 500 nanokelvins — just a hair above absolute zero, and over a million times colder than interstellar space. The researchers found that the ultracold molecules were relatively long-lived and stable, resisting reactive collisions with other molecules. The molecules also exhibited very strong dipole moments — strong imbalances in electric charge within molecules that mediate magnet-like forces between molecules over large distances.


Martin Zwierlein, professor of physics at MIT and a principal investigator in MIT’s Research Laboratory of Electronics, says that while molecules are normally full of energy, vibrating and rotating and moving through space at a frenetic pace, the group’s ultracold molecules have been effectively stilled — cooled to average speeds of centimeters per second and prepared in their absolute lowest vibrational and rotational states.


“We are very close to the temperature at which quantum mechanics plays a big role in the motion of molecules,” Zwierlein says. “So these molecules would no longer run around like billiard balls, but move as quantum mechanical matter waves. And with ultracold molecules, you can get a huge variety of different states of matter, like superfluid crystals, which are crystalline, yet feel no friction, which is totally bizarre.


This has not been observed so far, but predicted. We might not be far from seeing these effects, so we’re all excited.”

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Quantum hard drive breakthrough - prototype developed

Quantum hard drive breakthrough - prototype developed | Amazing Science | Scoop.it

Physicists developing a prototype quantum hard drive have improved storage time by a factor of more than 100


The team’s record storage time of six hours is a major step towards a secure worldwide data encryption network based on quantum information, which could be used for banking transactions and personal emails.


“We believe it will soon be possible to distribute quantum information between any two points on the globe,” said lead author Manjin Zhong, from the Research School of Physics and Engineering (RSPE).


Quantum states are very fragile and normally collapse in milliseconds. Our long storage times have the potential to revolutionise the transmission of quantum information.” Quantum information promises unbreakable encryption because quantum particles such as photons of light can be created in a way that intrinsically links them. Interactions with either of these entangled particles affect the other, no matter how far they are separated.


The team of physicists at ANU and the University of Otago stored quantum information in atoms of the rare earth element europium embedded in a crystal. Their solid-state technique is a promising alternative to using laser beams in optical fibers, an approach which is currently used to create quantum networks around 100 kilometers long.

“Our storage times are now so long that it means people need to rethink what is the best way to distribute quantum data,” Ms Zhong said.  “Even transporting our crystals at pedestrian speeds we have less loss than laser systems for a given distance.”


“We can now imagine storing entangled light in separate crystals and then transporting them to different parts of the network thousands of kilometers apart. So, we are thinking of our crystals as portable optical hard drives for quantum entanglement.” After writing a quantum state onto the nuclear spin of the europium using laser light, the team subjected the crystal to a combination of a fixed and oscillating magnetic fields to preserve the fragile quantum information.


“The two fields isolate the europium spins and prevent the quantum information leaking away,” said Dr Jevon Longdell of the University of Otago. The ANU group is also excited about the fundamental tests of quantum mechanics that a quantum optical hard drive will enable.

"We have never before had the possibility to explore quantum entanglement over such long distances," said Associate Professor Matthew Sellars, leader of the research team.


“We should always be looking to test whether our theories match up with reality. Maybe in this new regime our theory of quantum mechanics breaks.” Their research is published in Nature.

more...
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Donuts, math, and superdense teleportation of quantum information

Donuts, math, and superdense teleportation of quantum information | Amazing Science | Scoop.it

Putting a hole in the center of the donut—a mid-nineteenth-century invention—allows the deep-fried pastry to cook evenly, inside and out. As it turns out, the hole in the center of the donut also holds answers for a type of more efficient and reliable quantum information teleportation, a critical goal for quantum information science.


Quantum teleportation is a method of communicating information from one location to another without moving the physical matter to which the information is attached. Instead, the sender (Alice) and the receiver (Bob) share a pair of entangled elementary particles—in this experiment, photons, the smallest units of light—that transmit information through their shared quantum state. In simplified terms, Alice encodes information in the form of the quantum state of her photon. She then sends a key to Bob over traditional communication channels, indicating what operation he must perform on his photon to prepare the same quantum state, thus teleporting the information.


Quantum teleportation has been achieved by a number of research teams around the globe since it was first theorized in 1993, but current experimental methods require extensive resources and/or only work successfully a fraction of the time.


Now, by taking advantage of the mathematical properties intrinsic to the shape of a donut—or torus, in mathematical terminology—a research team led by physicist Paul Kwiat of the University of Illinois at Urbana-Champaign has made great strides by realizing “superdense teleportation”. This new protocol, developed by coauthor physicist Herbert Bernstein of Hampshire College in Amherst, MA, effectively reduces the resources and effort required to teleport quantum information, while at the same time improving the reliability of the information transfer.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Wheeler's delayed-choice gedanken experiment confirmed with a single atom

Wheeler's delayed-choice gedanken experiment confirmed with a single atom | Amazing Science | Scoop.it

The bizarre nature of reality as laid out by quantum theory has survived another test, with scientists performing a famous experiment and proving that reality does not exist until it is measured.


Physicists at The Australian National University (ANU) have conducted John Wheeler's delayed-choice thought experiment, which involves a moving object that is given the choice to act like a particle or a wave. Wheeler's experiment then asks - at which point does the object decide? Common sense says the object is either wave-like or particle-like, independent of how we measure it. But quantum physics predicts that whether you observe wave like behavior (interference) or particle behavior (no interference) depends only on how it is actually measured at the end of its journey. This is exactly what the ANU team found.

"It proves that measurement is everything. At the quantum level, reality does not exist if you are not looking at it," said Associate Professor Andrew Truscott from the ANU Research School of Physics and Engineering.


Despite the apparent weirdness, the results confirm the validity of quantum theory, which governs the world of the very small, and has enabled the development of many technologies such as LEDs, lasers and computer chips. The ANU team not only succeeded in building the experiment, which seemed nearly impossible when it was proposed in 1978, but reversed Wheeler's original concept of light beams being bounced by mirrors, and instead used atoms scattered by laser light.


"Quantum physics' predictions about interference seem odd enough when applied to light, which seems more like a wave, but to have done the experiment with atoms, which are complicated things that have mass and interact with electric fields and so on, adds to the weirdness," said Roman Khakimov, PhD student at the Research School of Physics and Engineering.


Professor Truscott's team first trapped a collection of helium atoms in a suspended state known as a Bose-Einstein condensate, and then ejected them until there was only a single atom left. The single atom was then dropped through a pair of counter-propagating laser beams, which formed a grating pattern that acted as crossroads in the same way a solid grating would scatter light. A second light grating to recombine the paths was randomly added, which led to constructive or destructive interference as if the atom had travelled both paths. When the second light grating was not added, no interference was observed as if the atom chose only one path.


However, the random number determining whether the grating was added was only generated after the atom had passed through the crossroads. If one chooses to believe that the atom really did take a particular path or paths then one has to accept that a future measurement is affecting the atom's past, said Truscott.


"The atoms did not travel from A to B. It was only when they were measured at the end of the journey that their wave-like or particle-like behavior was brought into existence," he said.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Single-electron fractionalization (dividing the electron into smaller "charge pulses") observed on picosecond scale

Single-electron fractionalization (dividing the electron into smaller "charge pulses") observed on picosecond scale | Amazing Science | Scoop.it

Coulomb interaction has a striking effect on electronic propagation in one-dimensional conductors. The interaction of an elementary excitation with neighboring conductors favors the emergence of collective modes, which eventually leads to the destruction of the Landau quasiparticle. In this process, an injected electron tends to fractionalize into separated pulses carrying a fraction of the electron charge. Here, a team of physicists now use two-particle interferences in the electronic analog of the Hong-Ou-Mandel experiment in a quantum Hall conductor at filling factor 2 to probe the fate of a single electron emitted in the outer edge channel and interacting with the inner one. By studying both channels, they analyze the propagation of the single electron and the generation of interaction-induced collective excitations in the inner channel. These complementary pieces of information reveal the fractionalization process in the time domain and establish its relevance for the destruction of the quasiparticle, which degrades into the collective modes.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Electrons move like light in three-dimensional bulk material

Electrons move like light in three-dimensional bulk material | Amazing Science | Scoop.it

Electrons were observed to travel in a solid at an unusually high velocity, which remained the same independent of the electron energy. This anomalous light-like behavior is found in special two-dimensional materials, such as graphene, but is now realized in a three-dimensional bulk material. High-resolution angle-resolved electron spectroscopy, stimulated by synchrotron x-ray radiation, was used to substantiate the theoretically predicted exotic electron structure.


A stable bulk material has been discovered that shows the same physics found in graphene, which illuminated the detailed interactions of electron's orbital motion and its intrinsic magnetic orientation. The new material will be a test ground for theories on how electron interactions in solids shape exotic electron behavior, including the highest electron mobility in bulk materials.


Investigations of electronic behavior have expanded beyond familiar systems of metals, insulators, and semi-conductors into the realm of strongly interacting electrons, which exhibit exotic relationships between the allowed electron velocities and their energy states. A key feature for the new materials is behavior in which the electron velocity does not depend on its energy. Such a relationship is a hallmark of photons, the energetic particles that make up a beam of light. This property is found in the new class of materials exhibiting a strong interaction between the electron trajectory and the electron spin alignment (called "spin-orbit coupling"). Two-dimensional versions of such systems (for example, grapheme) have been recently explored, but the systems are hard to work with because of their ultra-thin film nature.


This work establishes graphene-like electronic behavior in the bulk three-dimensional materials Na3Bi and Cd3As2 and explains their exceptionally high electronic mobility. The required advances in electron spectroscopy techniques, used to investigate the electronic structure, employed an energy tunable bright x-ray source and a high-resolution spectrometer.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Scientists tune X-rays with tiny mirrors

Scientists tune X-rays with tiny mirrors | Amazing Science | Scoop.it

The secret of X-ray science – like so much else – is in the timing. Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have created a new way of manipulating high-intensity X-rays, which will allow researchers to select extremely brief but precise X-ray bursts for their experiments.


The new technology, developed by a team of scientists from Argonne’s Center for Nanoscale Materials (CNM) and the Advanced Photon Source (APS), involves a small microelectromechanical system (MEMS) mirror only as wide as a few hairs.


MEMS are microscale devices fabricated using silicon wafers in facilities that make integrated circuits. The MEMS device acts as an ultrafast mirror reflecting X-rays at precise times and specific angles.


“Extremely compact devices such as this promise a revolution in our ability to manipulate photons coming from synchrotron light sources, not only providing an on-off switch enabling ultrahigh time-resolution studies, but ultimately promising new ways to steer, filter, and shape X-ray pulses as well,” said Stephen Streiffer, Associate Laboratory Director for Photon Sciences and Director of the Advanced Photon Source. “This is a premier example of the innovation that results from collaboration between nanoscientists and X-ray scientists.”


The device that the Argonne researchers developed essentially consists of a tiny diffracting mirror that oscillates at high speeds. As the mirror tilts rapidly back and forth, it creates an optical filter that selects only the X-ray pulses desired for the experiment. Only the light that is diffracted from the mirror goes on to hit the sample, and by adjusting the speed at which the MEMS mirror oscillates, researchers can control the timing of the X-ray pulses.


According to Argonne nanoscientist Daniel Lopez, one of the lead authors on the paper, the device works because of the relationship between the frequency of the mirror’s oscillation and the timing of the positioning of the perfect angle for the incoming X-ray. “If you sit on a Ferris wheel holding a mirror, you will see flashes of light every time the wheel is at the perfect spot for sunlight to hit it. The speed of the Ferris wheel determines the frequency of the flashes you see,” he said.


“The Argonne team’s work is incredibly exciting because it creates a new class of devices for controlling X-rays,” added Paul Evans, a professor of materials science at the University of Wisconsin-Madison. “They have found a way to significantly shrink the optics, which is great because smaller means faster, cheaper to make, and much more versatile.”

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Is the universe a hologram? New calculations show that this may be fundamental feature of space itself

Is the universe a hologram? New calculations show that this may be fundamental feature of space itself | Amazing Science | Scoop.it

At first glance, there is not the slightest doubt: to us, the universe looks three dimensional. But one of the most fruitful theories of theoretical physics in the last two decades is challenging this assumption. The "holographic principle" asserts that a mathematical description of the universe actually requires one fewer dimension than it seems. What we perceive as three dimensional may just be the image of two dimensional processes on a huge cosmic horizon.


Up until now, this principle has only been studied in exotic spaces with negative curvature. This is interesting from a theoretical point of view, but such spaces are quite different from the space in our own universe. Results obtained by scientists at TU Wien (Vienna) now suggest that the holographic principle even holds in a flat spacetime.


Gravitational phenomena are described in a theory with three spatial dimensions, the behavior of quantum particles is calculated in a theory with just two spatial dimensions - and the results of both calculations can be mapped onto each other. Such a correspondence is quite surprising. It is like finding out that equations from an astronomy textbook can also be used to repair a CD-player. But this method has proven to be very successful. More than ten thousand scientific papers about Maldacena's "AdS-CFT-correspondence" have been published to date.


For theoretical physics, this is extremely important, but it does not seem to have much to do with our own universe. Apparently, we do not live in such an anti-de-sitter-space. These spaces have quite peculiar properties. They are negatively curved, any object thrown away on a straight line will eventually return. "Our universe, in contrast, is quite flat - and on astronomic distances, it has positive curvature", says Daniel Grumiller.


However, Grumiller has suspected for quite some time that a correspondence principle could also hold true for our real universe. To test this hypothesis, gravitational theories have to be constructed, which do not require exotic anti-de-sitter spaces, but live in a flat space. For three years, he and his team at TU Wien (Vienna) have been working on that, in cooperation with the University of Edinburgh, Harvard, IISER Pune, the MIT and the University of Kyoto. Now Grumiller and colleagues from India and Japan have published an article in the journal Physical Review Letters, confirming the validity of the correspondence principle in a flat universe.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Photon afterglow could transmit information without transmitting energy

Photon afterglow could transmit information without transmitting energy | Amazing Science | Scoop.it

Physicists have theoretically shown that it is possible to transmit information from one location to another without transmitting energy. Instead of using real photons, which always carry energy, the technique uses a small, newly predicted quantum afterglow of virtual photons that do not need to carry energy. Although no energy is transmitted, the receiver must provide the energy needed to detect the incoming signal—similar to the way that an individual must pay to receive a collect call.


The physicists, Robert H. Jonsson, Eduardo Martín-Martínez, and Achim Kempf, at the University of Waterloo (Martín-Martínez and Kempf are also with the Perimeter Institute), have published a paper on the concept in a recent issue of Physical Review LettersCurrently, any information transmission protocol also involves energy transmission. This is because these protocols use real photons to transmit information, and all real photons carry energy, so the information and energy are inherently intertwined.


Most of the time when we talk about electromagnetic fields and photons, we are talking about real photons. The light that reaches our eyes, for example, consists only of real photons, which carry both information and energy. However, all electromagnetic fields contain not only real photons, but also virtual photons, which can be thought of as "imprints on the quantum vacuum." The new discovery shows that, in certain circumstances, virtual photons that do not carry energy can be used to transmit information.


The physicists showed how to achieve this energy-less information transmission by doing two things: "First, we use quantum antennas, i.e., antennas that are in a quantum superposition of states," Kempf told Phys.org. "For example, with current quantum optics technology, atoms can be used as such antennas. Secondly, we use the fact that, when real photons are emitted (and propagate at the speed of light), the photons leave a small afterglow of virtual photons that propagate slower than light. This afterglow does not carry energy (in contrast to real photons), but it does carry information about the event that generated the light. Receivers can 'tap' into that afterglow, spending energy to recover information about light that passed by a long time ago."


The proposed protocol has another somewhat unusual requirement: it can only take place in spacetimes with dimensions in which virtual photons can travel slower than the speed of light. For instance, the afterglow would not occur in our 3+1 dimensional spacetime if spacetime were completely flat. However, our spacetime does have some curvature, and that makes the afterglow possible.


These ideas also have implications for cosmology. In a paper to be published in a future issue of Physical Review Letters, Martín-Martínez and collaborators A. Blasco, L. Garay, and M. Martin-Benito have investigated these implications. "In that work, it is shown that the afterglow of events that happened in the early Universe carries more information than the light that reaches us from those events," Martín-Martínez said. "This is surprising because, up until now, it has been believed that real quanta, such as real photons of light, are the only carriers of information from the early Universe."

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Falling into a black hole may convert you into a hologram or you will hit a firewall of doom

Falling into a black hole may convert you into a hologram or you will hit a firewall of doom | Amazing Science | Scoop.it

In the movie Interstellar, the main character Cooper escapes from a black hole in time to see his daughter Murph in her final days. Some have argued that the movie is so scientific that it should be taught in schools. In reality, many scientists believe that anything sent into a black hole would probably be destroyed. But a new study suggests that this might not be the case after all. The research says that, rather than being devoured, a person falling into a black hole would actually be absorbed into a hologram — without even noticing. The paper challenges a rival theory stating that anybody falling into a black hole hits a “firewall” and is immediately destroyed.


Forty years ago, Stephen Hawking shocked the scientific establishment with his discovery that black holes aren’t really black. Classical physics implies that anything falling through the horizon of a black hole can never escape. But Hawking showed that black holes continually emit radiation once quantum effects are taken into account. Unfortunately, for typical astrophysical black holes, the temperature of this radiation is far lower than that of the cosmic microwave background, meaning detecting them is beyond current technology.


Hawking’s calculations are perplexing. If a black hole continually emits radiation, it will continually lose mass—eventually evaporating. Hawking realised that this implied a paradox: if a black hole can evaporate, the information about it will be lost forever. This means that even if we could measure the radiation from a black hole we could never figure out it was originally formed. This violates an important rule of quantum mechanics that states information cannot be lost or created.


Another way to look at this is that Hawking radiation poses a problem with determinism for black holes. Determinism implies that the state of the universe at any given time is uniquely determined from its state at any other time. This is how we can trace its evolution both astronomically and mathematically though quantum mechanics.


This means that the loss of determinism would have to arise from reconciling quantum mechanics with Einstein’s theory of gravity – a notoriously hard problem and ultimate goal for many physicists. Black hole physics provides a test for any potential quantum gravity theory. Whatever your theory is, it must explain what happens to the information recording a black hole’s history.


It took two decades for scientists to come up with a solution. They suggested that the information stored in a black hole is proportional to its surface area (in two dimensions) rather than its volume (in three dimensions). This could be explained by quantum gravity, where the three dimensions of space could be reconstructed from a two-dimensional world without gravity – much like a hologram. Shortly afterwards, string theory, the most studied theory of quantum gravity, was shown to be holographic in this way.


Using holography we can describe the evaporation of the black hole in the two-dimensional world without gravity, for which the usual rules of quantum mechanics apply. This process is deterministic, with small imperfections in the radiation encoding the history of the black hole. So holography tells us that information is not lost in black holes, but tracking down the flaw in Hawking’s original arguments has been surprisingly hard.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Material with superfast electrons exhibits extremely large magnetoresistance - source for new electronics?

Material with superfast electrons exhibits extremely large magnetoresistance - source for new electronics? | Amazing Science | Scoop.it

It may be significantly easier to design electronic components in future. Scientists at the Max Planck Institute for Chemical Physics of Solids have discovered that the electrical resistance of a compound of niobium and phosphorus increases enormously when the material is exposed to a magnetic field. This giant magnetoresistance, which is responsible for the large storage capacity of modern hard discs, was previously known to occur in some complexly structured materials. Niobium phosphide or a material with similar properties which can be manufactured more easily could offer an alternative. The Max Planck researchers, together with colleagues from the High-Field Magnet Laboratories at the Helmholtz-Zentrum Dresden-Rossendorf and at the Radboud University in the Netherlands, published the new findings on niobium phosphide in the journal Nature Physics.


Electronic systems are expected to process and store a steadily increasing amount of data, faster and faster, and in less space. Luckily, physicists discover effects that help engineers to develop better electronic components with surprising regularity, for instance a phenomenon known as giant magnetoresistance. Modern hard discs utilize this phenomenon to significantly alter the resistance of a material by exposing it to a magnetic field. Until now, the computer industry has used various materials stacked on top of each other in a filigree structure to achieve this effect. Now, Max Planck scientists in Dresden have observed a rapid increase in resistance by a factor of 10,000 in a non-complex material, namely niobium phosphide (NbP).


The resistance of niobium phosphide changes so dramatically in a magnetic field, because the charge carriers are deflected by a phenomenon known as the Lorentz force. This force causes an increasing percentage of electrons to start flowing in the "wrong" direction as the magnetic field is ramped up, thus increasing the electric resistance. Consequently, this property is known as magnetoresistance.


"The faster the electrons in the material move, the greater the Lorentz force and thus the effect of a magnetic field," explains Binghai Yan, a researcher at the Max Planck Institute for Chemical Physics of Solids in Dresden. He and his colleagues therefore came up with the idea of investigating a compound consisting of the transition metal niobium (Nb) and phosphorus. This material contains superfast charge carriers, known as relativistic electrons that move at around one thousandth the speed of light, or 300 kilometers per second.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Neutrinos found to switch to the elusive ‘tau’ flavor

Neutrinos found to switch to the elusive ‘tau’ flavor | Amazing Science | Scoop.it

Using a beam shot through the Earth's crust, physicists have found the first direct proof of a metamorphosis between two of the three known types of neutrinos — those known as ‘muon’ and ‘tau’ flavors of the elementary particles.


There are three known types, or flavors, of neutrino: electron, muon and tau. The particles’ names allude to the fact that on the rare occasions, when neutrinos interact with protons or neutrons, they variously produce electrons, muons or tau leptons. Scientists had long suspected that neutrinos can transform from one flavor to another. Several previous experiments that used known sources of particular types of neutrino have detected fewer neutrinos than would be expected if the particles did not change flavor.


In July 2013, the T2K experiment in Japan saw the first direct evidence of the appearance of a different flavor1 — rather than just the disappearance of the original one. It detected electron neutrinos in a beam originally made of muon neutrinos.


Between 2008 and 2012, a beam of muon neutrinos was shot from CERN, Europe's particle physics lab near Geneva, Switzerland, to the base of the Gran Sasso massif, 730 kilometers to the southeast, where the Italian lab is carved inside the rock.


By the time the neutrinos arrived at Gran Sasso, some of the muon neutrinos had turned into tau neutrinos. When these hit the lead targets inside the OPERA detector, they produced tau leptons, the latest results show. The leptons decay in just one-trillionth of a second, says Giovanni De Lellis, a physicist at the University of Naples who is the OPERA spokesperson. “Even though it travels at nearly the speed of light, [the tau lepton] only runs for less than a millimeter,” he says.


OPERA detected the short-lived particles with an array of 150,000 'bricks', each of which weighs about 8 kilograms and contains 57 stacked emulsion plates. This set-up has 110,000 square meters of surface area, so researchers set up an automated system to search the plates for microscopic streaks that would signal the brief presence of tau leptons.


In partial results announced last year2, the OPERA collaboration counted four probable tau lepton sightings, not quite enough to claim a success according to the stringent discovery criteria of particle physics. But the physicists have now found a fifth tau lepton, enough for the experiment to be declared successful. “The result could not be taken for granted,” he says. Once the CERN beam was shut off, De Lellis and his team were limited to searching through existing data, and finding five events took a bit of luck, he admits. “It could have been six — or four, or three.”

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Rayleigh scattering reveals light propagation in optical nanofibers

Rayleigh scattering reveals light propagation in optical nanofibers | Amazing Science | Scoop.it

Optical fibers are hair-like threads of glass used to guide light. Fibers of exceptional purity have proved an excellent way of sending information over long distances and are the foundation of modern telecommunication systems. Transmission relies on what's called total internal reflection, wherein the light propagates by effectively bouncing back and forth off of the fiber's internal surface. Though the word "total" implies light remains entirely trapped in the fiber, the laws of physics dictate that some of the light, in the form of what's called an evanescent field, also exists outside of the fiber. In telecommunications, the fiber core is more than ten times larger than the wavelength of light passing through. In this case, the evanescent fields are weak and vanish rapidly away from the fiber. Nanofibers have a diameter smaller than the wavelength of the guided light. Here, all of the light field cannot fit inside of the nanofiber, yielding a significant enhancement in the evanescent fields outside of the core. This allows the light to trap atoms (or other particles) near the surface of a nanofiber.


JQI researchers in collaboration with scientists from the Naval Research Laboratory have developed a new technique for visualizing light propagation through an optical nanofiber, detailed in a recent Optica paper. The result is a non-invasive measurement of the fiber size and shape and a real-time view of how light fields evolve along the nanofiber. Direct measurement of the fields in and around an optical nanofiber offers insight into how light propagates in these systems and paves the way for engineering customized evanescent atom traps.


In this work, researchers use a sensitive camera to collect light from what's known as Rayleigh scattering, demonstrating the first in-situ measurements of light moving through an optical nanofiber. Rayleigh scattering happens when light bounces, or scatters, off of particles much smaller than the wavelength of the light. In fibers, these particles can be impurities or density fluctuations in the glass, and the light scattered from them is ejected from the fiber. This allows one to view the propagating light from the side, in much the same way as one can see a beam of sunlight through fog. Importantly, the amount of light ejected depends on the polarization, or the orientation of oscillation of the light, and intensity of the field at each point, which means that capturing this light is a way to view the field.


The researchers here are interested in understanding the propagation of the field when the light waves are comprised from what are known as higher-order modes. Instead of having a uniform spatial profile, like that of a laser pointer, these modes can look like a doughnut, cloverleaf, or another more complicated pattern. Higher-order modes offer some advantages over the lowest order or "fundamental" mode. Due to their complexity, the evanescent field can have comparatively more light intensity in the region of interest—locally just outside the fiber. These higher order modes can also be used to make different types of optical patterns. Nanofibers aren't yet standardized and thus careful and complete characterization of both the fiber and the light passing through them is a necessary step towards making them a more practical and adaptable tool for research applications.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Superdense Teleportation: Transporting Quantum Information Without Moving Matter

Superdense Teleportation: Transporting Quantum Information Without Moving Matter | Amazing Science | Scoop.it

A team of scientists have taken quantum teleportation – a method of communicating information from one location to another without having to physically move it – to a higher level by using certain high-dimensional states (which they dubbed “donut” states) for teleportation. Stony Brook University physicist Tzu-Chieh Wei, PhD, and colleagues nationally demonstrated that their method works, is more reliable than previous teleportation schemes, and could be a stepping stone toward building a quantum communications network. Their findings appear in Nature Communications.


The researchers developed entangled elementary particles – in this case photons, the smallest units of light – to transmit information through a shared pair of entangled quantum state of photons – both the sender and receiver have one photon, one half of each entangled pair. In simple communication terms, the process of superdense-teleporting would involve one person to encode information in the form of a quantum state on his photon. Then the person would perform measurement on his photon and then use traditional communication channels (phone or email) to let the other person know what operation to perform on her photon in the laboratory to re-create the same quantum state.


“This process of a re-creation is essentially a transport without having any matter move from location A to location B,” said Dr. Wei, an Assistant Professor in Yang Institute for Theoretical Physics at Stony Brook University. “Loosely speaking you could also view teleportation as a miniature version of teletransportation in the ‘Star Trek’ movies.”


Dr. Wei also likened the teleportation method as quantum information created and then stored in a kind of invisible parallel “shared folder” for end users. A broadening and testing of this concept could help to form a quantum communications network that could potentially be used to encode and transmit useful quantities of quantum data for scientific experimentation and communication virtually anywhere on earth or in space.


In “Superdense teleportation using hyper-entangled photons,” the team took advantage of the mathematical properties intrinsic to the shape of a donut – or torus, in mathematical terms to use “superdense teleportation.” The work, led by physicist Paul Kwiat of the University of Illinois, built on this new protocol for teleportation that was developed by co-author physicist Herbert Bernstein of Hampshire College in Amherst, Mass. The method effectively reduces the resources required to teleport quantum information, while at the same time improving the rate and reliability of the information transfer.


With this new method, the researchers experimentally achieved 88 percent transmission fidelity, twice that of 44 percent, the very best that could be achieved by any system that didn’t have access to the entangled quantum resource. To make the whole process more efficient, the protocol uses pairs of photons that are “hyperentangled” – simultaneously entangled in more than one property, in this case in polarization and in orbital angular momentum – with a restricted number of possible states in each variable. Using multiple properties allows each photon to carry more information than the earlier quantum teleportation experiments.

more...
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Researchers prove that magnetism can control heat and sound

Researchers prove that magnetism can control heat and sound | Amazing Science | Scoop.it
Phonons—the elemental particles that transmit both heat and sound—have magnetic properties, according to a landmark study supported by Ohio Supercomputer Center (OSC) services and recently published by a researcher group from The Ohio State University.


In a recent issue of the journal Nature Materials, the researchers describe how a magnetic field, roughly the size of a medical MRI, reduced the amount of heat flowing through a semiconductor by 12 percent. Simulations performed at OSC then identified the reason for it—the magnetic field induces a diamagnetic response in vibrating atoms known as phonons, which changes how they transport heat.


"This adds a new dimension to our understanding of acoustic waves," said Joseph Heremans, Ph.D., Ohio Eminent Scholar in Nanotechnology and a professor of mechanical engineering at Ohio State whose group performed the experiments. "We've shown that we can steer heat magnetically. With a strong enough magnetic field, we should be able to steer sound waves, too."


People might be surprised enough to learn that heat and sound have anything to do with each other, much less that either can be controlled by magnets, Heremans acknowledged. But both are expressions of the same form of energy, quantum mechanically speaking. So any force that controls one should control the other.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Microscopic sonic screwdriver invented

Microscopic sonic screwdriver invented | Amazing Science | Scoop.it

The research by academics from the University of Bristol’s Department of Mechanical Engineering and Northwestern Polytechnical University in China, is published in Physical Review Letters.


The researchers have shown that acoustic vortices act like tornados of sound, causing microparticles to rotate and drawing them to the vortex core. Like a tornado, what happens to the particles depends strongly on their size.


Bruce Drinkwater, Professor of Ultrasonics in the Department of Mechanical Engineering and one of the authors of the study, said: “We have now shown that these vortices can rotate microparticles, which opens up potential applications such as the creation of microscopic centrifuges for biological cell sorting or small-scale, low-power water purification.


“If the large-scale acoustic vortex devices were thought of as sonic screwdrivers, we have invented the watchmakers sonic screwdriver.” The research team used a number of tiny ultra-sonic loudspeakers arranged in a circle to create the swirling sound waves. They found that when a mixture of small microparticles (less than 1 micron) and water were introduced they rotated slowly about the vortex core. However, larger microparticles (household flour) were drawn into the core and were seen to spin at high speeds or become stuck in a series of circular rings due to acoustic radiation forces.


Dr ZhenYu Hong, of the Department of Applied Physics at Northwestern Polytechnical University in China, added: “Previously researchers have shown that much larger objects, centimeters in scale, could be rotated with acoustic vortices, proving that they carry rotational momentum.”

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Rapid dynamic reprogramming of matter

Rapid dynamic reprogramming of matter | Amazing Science | Scoop.it

Engineering switchable reconfigurations in DNA-controlled nanoparticle arrays could lead to dynamic energy-harvesting or responsive optical materials


The rapid development of self-assembly approaches has enabled the creation of materials with desired organization of nanoscale components. However, achieving dynamic control, wherein the system can be transformed on demand into multiple entirely different states, is typically absent in atomic and molecular systems and has remained elusive in designed nanoparticle systems. Here, we demonstrate with in situ small-angle X-ray scattering that, by using DNA strands as inputs, the structure of a three-dimensional lattice of DNA-coated nanoparticles can be switched from an initial ‘mother phase into one of multiple ‘daughter phases. The introduction of different types of reprogramming DNA strands modifies the DNA shells of the nanoparticles within the superlattice, thereby shifting interparticle interactions to drive the transformation into a particular daughter phase. Moreover, we mapped quantitatively with free-energy calculations the selective reprogramming of interactions onto the observed daughter phases.


Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have developed the capability of creating dynamic nanomaterials — ones whose structure and associated properties can be switched, on-demand. In a paper appearing in Nature Materials, they describe a way to selectively rearrange nanoparticles in three-dimensional arrays to produce different configurations, or “phases,” from the same nano-components.


“One of the goals in nanoparticle self-assembly has been to create structures by design,” said Oleg Gang, who led the work at Brookhaven’s Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility. “Until now, most of the structures we’ve built have been static.” KurzweilAI covered that development in a previous article, “Creating complex structures using DNA origami and nanoparticles.”


The new advance in nanoscale engineering builds on that previous work in developing ways to get nanoparticles to self-assemble into complex composite arrays, including linking them together with tethers constructed of complementary strands of synthetic DNA.


“We know that properties of materials built from nanoparticles are strongly dependent on their arrangements,” said Gang. “Previously, we’ve even been able to manipulate optical properties by shortening or lengthening the DNA tethers. But that approach does not permit us to achieve a global reorganization of the entire structure once it’s already built.”

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Intense thunderclouds produce haze of antimatter photons that do not fit any known source of antiparticles

Intense thunderclouds produce haze of antimatter photons that do not fit any known source of antiparticles | Amazing Science | Scoop.it

When Joseph Dwyer’s aeroplane took a wrong turn into a thundercloud, the mistake paid off: the atmospheric physicist flew not only through a frightening storm but also into an unexpected — and mysterious — haze of antimatter. Although powerful storms have been known to produce positrons — the antimatter versions of electrons — the antimatter observed by Dwyer and his team cannot be explained by any known processes, they say. “This was so strange that we sat on this observation for several years,” says Dwyer, who is at the University of New Hampshire in Durham.


The flight took place six years ago, but the team is only now reporting the result (J. R. Dwyer et al. J. Plasma Phys.; in the press). “The observation is a puzzle,” says Michael Briggs, a physicist at the NASA Marshall Space Flight Center in Huntsville, Alabama, who was not involved in the report.


A key feature of antimatter is that when a particle of it makes contact with its ordinary-matter counterpart, both are instantly transformed into other particles in a process known as annihilation. This makes antimatter exceedingly rare. However, it has long been known that positrons are produced by the decay of radioactive atoms and by astrophysical phenomena, such as cosmic rays plunging into the atmosphere from outer space. In the past decade, research by Dwyer and others has shown that storms also produce positrons, as well as highly energetic photons, or γ-rays.


It was to study such atmospheric γ-rays that Dwyer, then at the Florida Institute of Technology in Melbourne, fitted a particle detector on a Gulfstream V, a type of jet plane typically used by business executives. On 21 August 2009, the pilots turned towards what looked, from its radar profile, to be the Georgia coast. “Instead, it was a line of thunderstorms — and we were flying right through it,” Dwyer says. The plane rolled violently back and forth and plunged suddenly downwards. “I really thought I was going to die.”


During those frightening minutes, the detector picked up three spikes in γ-rays at an energy of 511 kiloelectronvolts, the signature of a positron annihilating with an electron. Each γ-ray spike lasted about one-fifth of a second, Dwyer and his collaborators say, and was accompanied by some γ-rays of slightly lower energy. The team concluded that those γ-rays had lost energy as a result of travelling some distance and calculated that a short-lived cloud of positrons, 1–2 kilometres across, had surrounded the aircraft. But working out what could have produced such a cloud has proved hard. “We tried for five years to model the production of the positrons,” says Dwyer.


Electrons discharging from charged clouds accelerate to close to the speed of light, and can produce highly energetic γ-rays, which in turn can generate an electron–positron pair when they hit an atomic nucleus. But the team did not detect enough γ-rays with sufficient energy to do this.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Scientists have discovered a new state of matter, called 'Jahn-Teller metals'

Scientists have discovered a new state of matter, called 'Jahn-Teller metals' | Amazing Science | Scoop.it

An international team of scientists has announced the discovery of a new state of matter in a material that appears to be an insulator, superconductor, metal and magnet all rolled into one, saying that it could lead to the development of more effective high-temperature superconductors.


Why is this so exciting? Well, if these properties are confirmed, this new state of matter will allow scientists to better understand why some materials have the potential to achieve superconductivity at a relativity high critical temperature (Tc) - "high" as in −135 °C as opposed to −243.2 °C. Because superconductivity allows a material to conduct electricity without resistance, which means no heat, sound, or any other form of energy release, achieving this would revolutionise how we use and produce energy, but it’s only feasible if we can achieve it at so-called high temperatures.


As Michael Byrne explains, when we talk about states of matter, it’s not just solids, liquids, gases, and maybe plasmas that we have to think about. We also have to consider the more obscure states that don’t occur in nature, but are rather created in the lab - Bose–Einstein condensate, degenerate matter, supersolids and superfluids, and quark-gluon plasma, for example. 


By introducing rubidium into carbon-60 molecules - more commonly known as 'buckyballs' - a team led by chemist Kosmas Prassides from Tokohu University in Japan was able to change the distance between them, which forced them into a new, crystalline structure. When put through an array of tests, this structure displayed a combination of insulating, superconducting, metallic, and magnetic phases, including a brand new one, which the researchers have named 'Jahn-Teller metals'. 


Named after the Jahn-Teller effect, which is used in chemistry to describe how at low pressures, the geometric arrangement of molecules and ions in an electronic state can become distorted, this new state of matter allows scientists to transform an insulator - which can’t conduct electricity - into a conductor by simply applying pressure.


There’s a whole lot of lab-work to be done before this discovery will mean anything for practical energy production in the real world, but that’s science for you. And it’s got people excited already, as chemist Elisabeth Nicol from the University of Guelph in Canada told Hamish Johnston at PhysicsWorld: "Understanding the mechanisms at play and how they can be manipulated to change the Tc surely will inspire the development of new superconducting materials".

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Cloud of quantum particles can have several temperatures at once

Cloud of quantum particles can have several temperatures at once | Amazing Science | Scoop.it

The air around us consists of countless molecules, moving around randomly. It would be utterly impossible to track them all and to describe all their trajectories. But for many purposes, this is not necessary. Properties of the gas can be found which describe the collective behaviour of all the molecules, such as the air pressure or the temperature, which results from the particles' energy. On a hot summer's day, the molecules move at about 430 meters per second, in winter, it is a bit less.


This statistical view (which was developed by the Viennese physicist Ludwig Boltzmann) has proved to be extremely successful and describes many different physical systems, from pots of boiling water to phase transitions in liquid crystals in LCD-displays. However, in spite of huge efforts, open questions have remained, especially with regard to quantum systems. How the well-known laws of statistical physics emerge from many small quantum parts of a system remains one of the big open questions in physics.


Scientists at the Vienna University of Technology have now succeeded in studying the behaviour of a quantum physical multi-particle system in order to understand the emergence of statistical properties. The team of Professor Jörg Schmiedmayer used a special kind of microchip to catch a cloud of several thousand atoms and cool them close to absolute zero at -273°C, where their quantum properties become visible.


The experiment showed remarkable results: When the external conditions on the chip were changed abruptly, the quantum gas could take on different temperatures at once. It can be hot and cold at the same time. The number of temperatures depends on how exactly the scientists manipulate the gas. "With our microchip we can control the complex quantum systems very well and measure their behaviour", says Tim Langen, leading author of the paper published in Science. There had already been theoretical calculations predicting this effect, but it has never been possible to observe it and to produce it in a controlled environment.


The experiment helps scientists to understand the fundamental laws of quantum physics and their relationship with the statistical laws of thermodynamics. This is relevant for many different quantum systems, maybe even for technological applications. Finally, the results shed some light on the way our classical macroscopic world emerges from the strange world of tiny quantum objects.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

MIT scientists developed a new tabletop instrument that can detect individual electrons in a radioactive gas

MIT scientists developed a new tabletop instrument that can detect individual electrons in a radioactive gas | Amazing Science | Scoop.it
The new instrument is expected to help scientists measure the mass of a neutrino -- something that has not been done accurately so far.


Scientists at the Massachusetts Institute of Technology (MIT) have developed a new tabletop instrument that can detect individual electrons in a radioactive gas. The development of the new particle detector is being considered as a major step toward measuring the mass of a neutrino, a particle smaller than an atom and with no electrical charge.


As a radioactive gas decays and emits electrons, the detector -- created as part of an experiment dubbed “Project 8” -- uses a magnet to trap them in a magnetic bottle. A radio antenna then catches very weak signals released by the electrons, which, according to scientists, can be used to accurately map the electrons’ activity over several milliseconds. The latest findings were published in the journal Physical Review Letters on Monday.


“We can literally image the frequency of the electron, and we see this electron suddenly pop into our radio antenna,” Joe Formaggio, an associate professor of physics at MIT, said in a statement. “Over time, the frequency changes, and actually chirps up. So these electrons are chirping in radio waves.”


As part of the new study, the researchers recorded the activity of more than 100,000 individual electrons in Krypton gas. According to them, the newly developed instrument can help measure the mass of a neutrino, which is believed to be extremely difficult to detect as it does not appear to interact with ordinary matter.

more...
No comment yet.