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Physicists in Israel have created a quantum interferometer on an atom chip. This device can be used to explore the fundamentals of quantum theory by studying the interference pattern between two beams of atoms. University of Groningen physicist, Anupam Mazumdar, describes how the device could be adapted to use mesoscopic particles instead of atoms. This modification would allow for expanded applications. A description of the device, and theoretical considerations concerning its application by Mazumdar, were published on 28 May in the journal Science Advances.

The device, created by scientists from the Ben-Gurion University of the Negev, is a so-called Stern Gerlach interferometer, which was first proposed 100 years ago by German physicists Otto Stern and Walter Gerlach. Their original aim of creating an interferometer with freely propagating atoms exposed to gradients from macroscopic magnets has not been practically realized until now. “Such experiments have been done using photons, but never with atoms,” explains Anupam Mazumdar, Professor of Theoretical Physics at the University of Groningen and one of the co-authors of the article in Science Advances.

The Israeli scientists, led by Professor Ron Folman, created an interferometer on an atom chip, which can confine and/or manipulate atoms. A beam of rubidium atoms is levitated over the chip using magnets. Magnetic gradients are used to split the beam according to the spin values of the individual atoms. Spin is a magnetic moment that can have two values, either up or down. The spin-up and spin-down atoms are separated by a magnetic gradient. Subsequently, the two divergent beams are brought together again and recombined. The spin values are then measured, and an interference pattern is formed. Spin is a quantum phenomenon, and throughout this interferometer, the opposing spins are entangled. This makes the interferometer sensitive to other quantum phenomena.

MIT engineers have discovered a new way of generating electricity using tiny carbon particles that can create a current simply by interacting with liquid surrounding them.

The liquid, an organic solvent, draws electrons out of the particles, generating a current that could be used to drive chemical reactions or to power micro-or nanoscale robots, the researchers say.

“This mechanism is new, and this way of generating energy is completely new,” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT. “This technology is intriguing because all you have to do is flow a solvent through a bed of these particles. This allows you to do electrochemistry, but with no wires.”

Researchers have found that graphene-enhanced hard drives can store data at ten times the density of existing HDDs.

By leveraging the wonder material graphene, a group at the University of Cambridge is claiming an advance in data storage that resembles more of a leap than a step forward. The new design unlocks higher operating temperatures for hard disk drives (HDDs) and with it, unprecedented data density, which the team says represents a ten-fold increase on current technologies.

In a HDD, data is written onto fast-spinning platters by a moving magnetic head. Special layers called carbon-based overcoats (COCs) protect these platters from mechanical damage and corrosion during operation, though these can only perform within a certain temperature range and also take up a lot of space.

Continue reading “High-density hard drive packed with graphene stores 10 times the data” »

To test the Standard Model of particle physics, scientists often collide particles using gigantic underground rings. In a similar fashion, high-pressure physicists compress materials to ever greater pressures to further test the quantum theory of condensed matter and challenge predictions made using the most powerful computers.

Pressures exceeding 1 million atmospheres are capable of dramatically deforming atomic electronic clouds and alter how atoms are packed together. This leads to new chemical bonding and has revealed extraordinary behaviors such as helium rain, the transformation of sodium into a transparent metal, the emergence of superionic water ice and the transformation of hydrogen into a metallic fluid.

With new techniques constantly advancing the frontier of high–pressure physics, terapascal (TPa) pressures that were once inaccessible can now be achieved in the laboratory using static or dynamic compression (1 TPa is equivalent to approximately 10 million atmospheres).

In the cold, dense medium of a helium-3 superfluid, scientists recently made an unexpected discovery. A foreign object travelling through the medium could exceed a critical speed limit without breaking the fragile superfluid itself.

As this contradicts our understanding of superfluidity, it presented quite a puzzle — but now, by recreating and studying the phenomenon, physicists have figured out how it happens. Particles in the superfluid stick to the object, shielding it from interacting with the bulk superfluid, thus preventing the superfluid’s breakdown.

“Superfluid helium-3 feels like a vacuum to a rod moving through it, although it is a relatively dense liquid. There is no resistance, none at all,” said physicist Samuli Autti of Lancaster University in the UK. “I find this very intriguing.”

O,.o! Woah

When heavy ions, accelerated to the speed of light, collide with each other in the depths of European or American accelerators, quark-gluon plasma is formed for fractions of a second, or even its “cocktail” seasoned with other particles. According to scientists from the IFJ PAN, experimental data show that there are underestimated actors on the scene: photons. Their collisions lead to the emission of seemingly excess particles, the presence of which could not be explained.

Quark-gluon plasma is undoubtedly the most exotic state of matter thus far known to us. In the LHC at CERN near Geneva, it is formed during central collisions of two lead ions approaching each other from opposite directions, traveling at velocities very close to that of light. This quark-gluon soup is also sometimes seasoned with other particles. Unfortunately, the theoretical description of the course of events involving plasma and a cocktail of other sources fails to describe the data collected in the experiments.

Continue reading “Creation Without Contact in the Collisions of Lead and Gold Nuclei” »

Smashing together lead particles at 99.9999991 percent the speed of light, scientists have recreated the first matter that appeared after the Big Bang.

Out of the wreck came a primordial type of matter known as quark-gluon plasma, or QGP. It only lasted a fraction of a second, but for the first time, scientists were able to probe the plasma’s liquid-like characteristics – finding it to have less resistance to flow than any other known substance – and determine how it evolved in the first moments in the early Universe.

Physicists at the University of Bath in the UK, in collaboration with researchers from the USA, have uncovered a new mechanism for enabling magnetism and superconductivity to co-exist in the same material. Until now, scientists could only guess how this unusual coexistence might be possible. The discovery could lead to applications in green energy technologies and in the development of superconducting devices, such as next-generation computer hardware.

As a rule, superconductivity (the ability of a material to pass an electrical current with perfect efficiency) and magnetism (seen at work in fridge magnets) make poor bedfellows because the alignment of the tiny electronic magnetic particles in ferromagnets generally leads to the destruction of the electron pairs responsible for superconductivity. Despite this, the Bath researchers have found that the iron-based superconductor RbEuFe4As4, which is superconducting below-236°C, exhibits both superconductivity and magnetism below-258°C.

Physics postgraduate research student David Collomb, who led the research, explained: There’s a state in some materials where, if you get them really cold—significantly colder than the Antarctic—they become superconducting. But for this superconductivity to be taken to next-level applications, the material needs to show co-existence with magnetic properties. This would allow us to develop devices operating on a magnetic principle, such as magnetic memory and computation using magnetic materials, to also enjoy the benefits of superconductivity.

A team at Stony Brook University used ORNL’s Summit supercomputer to model x-ray burst flames spreading across the surface of dense neutron stars.

At the heart of some of the smallest and densest stars in the universe lies nuclear matter that might exist in never-before-observed exotic phases. Neutron stars, which form when the cores of massive stars collapse in a luminous supernova explosion, are thought to contain matter at energies greater than what can be achieved in particle accelerator experiments, such as the ones at the Large Hadron Collider and the Relativistic Heavy Ion Collider.

Although scientists cannot recreate these extreme conditions on Earth, they can use neutron stars as ready-made laboratories to better understand exotic matter. Simulating neutron stars, many of which are only 12.5 miles in diameter but boast around 1.4 to 2 times the mass of our sun, can provide insight into the matter that might exist in their interiors and give clues as to how it behaves at such densities.