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Category: particle physics

The development of technologies which can process information based on the laws of quantum physics are predicted to have profound impacts on modern society.

For example, quantum computers may hold the key to solving problems that are too complex for today’s most powerful supercomputers, and a quantum internet could ultimately protect the worlds information from malicious attacks.

However, these technologies all rely on “,” which is typically encoded in single quantum particles that are extremely difficult to control and measure.

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Here on Earth, you can see the aurora of the Northern Lights, when solar winds interact with the planet’s magnetosphere. It turns out that Mars has its own auroras too, called proton auroras, but they give off ultraviolet light which makes them invisible to the naked eye.

NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft, however, currently in orbit around Mars, is able to detect these auroras using its Imaging UltraViolet Spectrograph (IUVS) instrument. Using data from this instrument, scientists have been investigating the relationship between the proton auroras and the fact that Mars lost its water over time. The Martian aurora is indirectly created by hydrogen in the atmosphere, which comes from water being lost into space.

The animation below shows how the proton aurora is formed. First, solar winds send protons toward Mars, where they interact with a cloud of hydrogen surrounding the planet. The protons take electrons from the hydrogen atoms to become neutrons. These neutral particles can then pass through a region of the planet’s magnetosphere called the bow shock. When the hydrogen atoms enter the atmosphere and collide with gas particles, they give off the ultraviolet light that we call an aurora.

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A team of mathematicians from the University of North Carolina at Chapel Hill and Brown University has discovered a new phenomenon that generates a fluidic force capable of moving and binding particles immersed in density-layered fluids. The breakthrough offers an alternative to previously held assumptions about how particles accumulate in lakes and oceans and could lead to applications in locating biological hotspots, cleaning up the environment and even in sorting and packing.

How matter settles and aggregates under gravitation in systems, such as lakes and oceans, is a broad and important area of scientific study, one that greatly impacts humanity and the planet. Consider “marine snow,” the shower of organic matter constantly falling from upper waters to the deep ocean. Not only is nutrient-rich essential to the global food chain, but its accumulations in the briny deep represent the Earth’s largest carbon sink and one of the least-understood components of the planet’s carbon cycle. There is also the growing concern over microplastics swirling in ocean gyres.

Ocean particle accumulation has long been understood as the result of chance collisions and adhesion. But an entirely different and unexpected phenomenon is at work in the , according to a paper published Dec. 20 in Nature Communications by a team led by professors Richard McLaughlin and Roberto Camassa of the Carolina Center for Interdisciplinary Applied Mathematics in the College of Arts & Sciences, along with their UNC-Chapel Hill graduate student Robert Hunt and Dan Harris of the School of Engineering at Brown University.

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O.o.

The universe is almost devoid of antimatter, and physicists haven’t yet figured out why. Discovering any slight difference between the behaviour of antimatter and matter in Earth’s gravitational field could shed light on this question. Positronium atoms, which consist of an electron and a positron, are one type of antimatter atoms being considered to test whether antimatter falls at the same rate as matter in Earth’s gravitational field. But they are short-lived, lasting a mere 142 nanoseconds – too little to perform an antimatter gravity experiment. Researchers are therefore actively seeking tricks to make sources of positronium atoms that live longer. In a paper published today in the journal Physical Review A, the AEgIS collaboration at CERN describes a new way of making long-lived positronium.

To be useful for gravity experiments, a source of atoms needs to produce long-lived atoms in , and with known velocities that can be controlled and are unaffected by disturbances such as electric and magnetic fields. The new AEgIS source ticks all of these boxes, producing some 80 000 positronium atoms per minute that last 1140 nanoseconds each and have a known velocity (between 70 and 120 kilometres per second) that can be controlled with a high precision (10 kilometres per second).

The trick? Using a special positron-to-positronium converter to produce the atoms and a single flash of ultraviolet laser light that kills two birds with one stone. The laser brings the atoms from the lowest-energy electronic state to a long-lived higher-energy state and can select among all of the atoms only those with a certain velocity.

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Since the end of the 19th century, physicists have known that the transfer of energy from one body to another is associated with entropy. It quickly became clear that this quantity is of fundamental importance, and so began its triumphant rise as a useful theoretical quantity in physics, chemistry and engineering. However, it is often very difficult to measure. Professor Dietmar Block and Frank Wieben of Kiel University (CAU) have now succeeded in measuring entropy in complex plasmas, as they reported recently in the renowned scientific journal Physical Review Letters. In a system of charged microparticles within this ionized gas, the researchers were able to measure all positions and velocities of the particles simultaneously. In this way, they were able to determine the entropy, as it was already described theoretically by the physicist Ludwig Boltzmann around 1880.

Surprising thermodynamic equilibrium in plasma

“With our experiments, we were able to prove that in the important model system of complex , the thermodynamic fundamentals are fulfilled. What is surprising is that this applies to microparticles in a plasma, which is far away from thermodynamic equilibrium,” explains Ph.D. student Frank Wieben. In his experiments, he is able to adjust the thermal motion of the microparticles by means of a laser beam. Using video microscopy, he can observe the dynamic behaviour of the particles in real time, and determine the from the information collected.

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Teams have looked for a “fifth force” in the universe within the Earth’s mantle, ultra-vacuum chambers, and in hypothetical particles such as “X17.” Finding it could help explain mysteries around dark matter and dark energy.

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This could usher in higgs exotic physics computing that is beyond even quantum computers.

When a continuous symmetry of a physical system is spontaneously broken, two types of collective modes typically emerge: the amplitude and phase modes of the order-parameter fluctuation. For superconductors, the amplitude mode is recently referred to as the ‘’Higgs mode’’ as it is a condensed-matter analogue of a Higgs boson in particle physics. Higgs mode is a scalar excitation of the order parameter, distinct from charge or spin fluctuations, and thus does not couple to electromagnetic fields linearly. This is why the Higgs mode in superconductors has evaded experimental observations over a half century after the initial theoretical prediction, except for a charge-density-wave coexisting system.

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Circa 2018

Higgs and Goldstone modes are possible collective modes of an order parameter on spontaneously breaking a continuous symmetry. Whereas the low-energy Goldstone (phase) mode is always stable, additional symmetries are required to prevent the Higgs (amplitude) mode from rapidly decaying into low-energy excitations. In high-energy physics, where the Higgs boson1 has been found after a decades-long search, the stability is ensured by Lorentz invariance. In the realm of condensed-matter physics, particle–hole symmetry can play this role2 and a Higgs mode has been observed in weakly interacting superconductors3,4,5. However, whether the Higgs mode is also stable for strongly correlated superconductors in which particle–hole symmetry is not precisely fulfilled or whether this mode becomes overdamped has been the subject of numerous discussions6,7,8,9,10,11. Experimental evidence is still lacking, in particular owing to the difficulty of exciting the Higgs mode directly. Here, we observe the Higgs mode in a strongly interacting superfluid Fermi gas. By inducing a periodic modulation of the amplitude of the superconducting order parameter Δ, we observe an excitation resonance at the frequency 2Δ/h. For strong coupling, the peak width broadens and eventually the mode disappears when the Cooper pairs turn into tightly bound dimers signalling the eventual instability of the Higgs mode.

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