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Category: particle physics

The detection of the axion would mark a key episode in the history of science. This hypothetical particle could resolve two fundamental problems of Modern Physics at the same time: the problem of Charge and Parity in the strong interaction, and the mystery of dark matter. However, in spite of the high scientific interest in finding it, the search at high radio frequency-above 6 GHz-has been almost left aside for the lack of the high sensitivity technology which could be built at reasonable cost. Until now.

The Instituto de Astrofísica de Canarias (IAC) will participate in an international collaboration to develop the DALI (Dark-photons & Axion-Like particles Interferometer) experiment, an astro-particle telescope for dark matter whose scientific objective is the search for axions and paraphotons in the 6 to 60 GHz band. The prototype, proof of concept, is currently in the design and fabrication phase at the IAC. The white-paper describing the experiment has been accepted for publication in the Journal of Cosmology and Astroparticle Physics (JCAP).

Predicted by theory in the 1970’s, the axion is a hypothetical low mass particle that interacts weakly with standard particles such as nucleons and electrons, as well as with photons. These proposed interactions are studied to try to detect the axion with different types of instruments. One promising technique is to study the interaction of axions with standard photons.

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Breakthrough in quantum chemistry has implications for quantum technology.

Quantum technology has a lot of promise, but several research barriers need to be overcome before it can be widely used. A team of US researchers has advanced the field another step, by bringing multiple molecules into a single quantum state at the same time.

A Bose-Einstein condensate is a state of matter that only occurs at very low temperatures – close to absolute zero. At this temperature, multiple particles can clump together and behave as though they were a single atom – something that could be useful in quantum technology. But while scientists have been able to get single atoms into this state for decades, they hadn’t yet achieved it with molecules.

“Atoms are simple spherical objects, whereas molecules can vibrate, rotate, carry small magnets,” says Cheng Chin, a professor of physics at the University of Chicago, US. “Because molecules can do so many different things, it makes them more useful, and at the same time much harder to control.”

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Protocol to reverse engineer Hamiltonian models advances automation of quantum devices.

Scientists from the University of Bristol ’s Quantum Engineering Technology Labs (QETLabs) have developed an algorithm that provides valuable insights into the physics underlying quantum systems — paving the way for significant advances in quantum computation and sensing, and potentially turning a new page in scientific investigation.

In physics, systems of particles and their evolution are described by mathematical models, requiring the successful interplay of theoretical arguments and experimental verification. Even more complex is the description of systems of particles interacting with each other at the quantum mechanical level, which is often done using a Hamiltonian model. The process of formulating Hamiltonian models from observations is made even harder by the nature of quantum states, which collapse when attempts are made to inspect them.

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Extremely precise measurements are possible using atom interferometers that employ the wave character of atoms for this purpose. They can thus be used, for example, to measure the gravitational field of the Earth or to detect gravitational waves. A team of scientists from Germany has now managed to successfully perform atom interferometry in space for the first time – onboard a sounding rocket. “We have established the technological basis for atom interferometry on board of a sounding rocket and demonstrated that such experiments are not only possible on Earth, but also in space,” said Professor Patrick Windpassinger of the Institute of Physics at Johannes Gutenberg University Mainz (JGU), whose team was involved in the investigation. The results of their analyses have been published in Nature Communications.

A team of researchers from various universities and research centers led by Leibniz University Hannover launched the MAIUS-1 mission in January 2017. This has since become the first rocket mission on which a Bose-Einstein condensate has been generated in space. This special state of matter occurs when atoms – in this case atoms of rubidium – are cooled to a temperature close to absolute zero, or minus 273 degrees Celsius. “For us, this ultracold ensemble represented a very promising starting point for atom interferometry,” explained Windpassinger. Temperature is one of the determining factors, because measurements can be carried out more accurately and for longer periods at lower temperatures.

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Findings could help explain how air pollutants interact with the atmosphere.

Researchers at the University of British Columbia, University of California Irvine, and McGill University have discovered three liquid phases in aerosol particles, changing our understanding of air pollutants in the Earth’s atmosphere.

While aerosol particles were known to contain up to two liquid phases, the discovery of an additional liquid phase may be important to providing more accurate atmospheric models and climate predictions. The study was published recently in PNAS.

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Starburst galaxies, active galactic nuclei and tidal disruption events (from left) have emerged as top candidates for the dominant source of ultrahigh-energy cosmic rays.

In the 1930s, the French physicist Pierre Auger placed Geiger counters along a ridge in the Alps and observed that they would sometimes spontaneously click at the same time, even when they were up to 300 meters apart. He knew that the coincident clicks came from cosmic rays, charged particles from space that bang into air molecules in the sky, triggering particle showers that rain down to the ground. But Auger realized that for cosmic rays to trigger the kind of enormous showers he was seeing, they must carry fantastical amounts of energy — so much that, he wrote in 1939, “it is actually impossible to imagine a single process able to give to a particle such an energy.”

Upon constructing larger arrays of Geiger counters and other kinds of detectors, physicists learned that cosmic rays reach energies at least 100000 times higher than Auger supposed.

A cosmic ray is just an atomic nucleus — a proton or a cluster of protons and neutrons. Yet the rare ones known as “ultrahigh-energy” cosmic rays have as much energy as professionally served tennis balls. They’re millions of times more energetic than the protons that hurtle around the circular tunnel of the Large Hadron Collider in Europe at 99.9999991% of the speed of light. In fact, the most energetic cosmic ray ever detected, nicknamed the “Oh-My-God particle,” struck the sky in 1991 going something like 99.99999999999999999999951% of the speed of light, giving it roughly the energy of a bowling ball dropped from shoulder height onto a toe. “You would have to build a collider as large as the orbit of the planet Mercury to accelerate protons to the energies we see,” said Ralph Engel, an astrophysicist at the Karlsruhe Institute of Technology in Germany and the co-leader of the world’s largest cosmic-ray observatory, the Pierre Auger Observatory in Argentina.

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Nuclear physicists make new, high-precision measurement of the layer of neutrons that encompass the lead nucleus, revealing new information about neutron stars.

Nuclear physicists have made a new, highly accurate measurement of the thickness of the neutron “skin” that encompasses the lead nucleus in experiments conducted at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility and just published in Physical Review Letters. The result, which revealed a neutron skin thickness of .28 millionths of a nanometer, has important implications for the structure and size of neutron stars.

The protons and neutrons that form the nucleus at the heart of every atom in the universe help determine each atom’s identity and properties. Nuclear physicists are studying different nuclei to learn more about how these protons and neutrons act inside the nucleus. The Lead Radius Experiment collaboration, called PREx (after the chemical symbol for lead, Pb), is studying the fine details of how protons and neutrons are distributed in lead nuclei.

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Circa 2020 o.o!

Researchers have succeeded in creating an efficient quantum-mechanical light-matter interface using a microscopic cavity. Within this cavity, a single photon is emitted and absorbed up to 10 times by an artificial atom. This opens up new prospects for quantum technology, report physicists at the University of Basel and Ruhr-University Bochum in the journal Nature.

Quantum physics describes photons as light particles. Achieving an interaction between a single photon and a single atom is a huge challenge due to the tiny size of the atom. However, sending the photon past the atom several times by means of mirrors significantly increases the probability of an interaction.

In order to generate photons, the researchers use artificial atoms, known as quantum dots. These semiconductor structures consist of an accumulation of tens of thousands of atoms, but behave much like a single atom: when they are optically excited, their energy state changes and they emit a photon. “However, they have the technological advantage that they can be embedded in a semiconductor chip,” says Dr. Daniel Najer, who conducted the experiment at the Department of Physics at the University of Basel.

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Circa 2020 o.,.o!

By Leah Crane.

Google researchers have used a quantum computer to simulate a chemical reaction for the first time. The reaction is a simple one, but this marks a step towards finding a practical use for quantum computers.

Because atoms and molecules are systems governed by quantum mechanics, quantum computers are expected to be the best way to precisely simulate them. These computers use quantum bits, or qubits, to store information and perform calculations. However, quantum computers have difficulty achieving the precision needed to simulate large atoms or chemical reactions.

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Nuclear physicists have made a new, highly accurate measurement of the thickness of the neutron “skin” that encompasses the lead nucleus in experiments conducted at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility and just published in Physical Review Letters. The result, which revealed a neutron skin thickness of .28 millionths of a nanometer, has important implications for the structure and size of neutron stars.

The protons and neutrons that form the nucleus at the heart of every atom in the universe help determine each atom’s identity and properties. Nuclear physicists are studying different nuclei to learn more about how these protons and neutrons act inside the nucleus. The Lead Radius Experiment collaboration, called PREx (after the chemical symbol for lead, Pb), is studying the fine details of how protons and neutrons are distributed in lead nuclei.

“The question is about where the neutrons are in lead. Lead is a heavy nucleus—there’s extra neutrons, but as far as the is concerned, an equal mix of protons and neutrons works better,” said Kent Paschke, a professor at the University of Virginia and experiment co-spokesperson.

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