Lifeboat Foundation

It could hardly be more complicated: tiny particles whir around wildly with extremely high energy, countless interactions occur in the tangled mess of quantum particles, and this results in a state of matter known as “quark-gluon plasma”. Immediately after the Big Bang, the entire universe was in this state; today it is produced by high-energy atomic nucleus collisions, for example at CERN.

Such processes can only be studied using high-performance computers and highly complex computer simulations whose results are difficult to evaluate. Therefore, using artificial intelligence or machine learning for this purpose seems like an obvious idea. Ordinary machine-learning algorithms, however, are not suitable for this task. The mathematical properties of particle physics require a very special structure of neural networks. At TU Wien (Vienna), it has now been shown how neural networks can be successfully used for these challenging tasks in particle physics.

Roughly 13.8 billion years ago, our Universe was born in a massive explosion that gave rise to the first subatomic particles and the laws of physics as we know them. About 370,000 years later, hydrogen had formed, the building block of stars, which fuse hydrogen and helium in their interiors to create all the heavier elements. While hydrogen remains the most pervasive element in the Universe, it can be difficult to detect individual clouds of hydrogen gas in the interstellar medium (ISM).

This makes it difficult to research the early phases of star formation, which would offer clues about the evolution of galaxies and the cosmos. An international team led by astronomers from the Max Planck Institute of Astronomy (MPIA) recently noticed a massive filament of atomic hydrogen gas in our galaxy. This structure, named “Maggie,” is located about 55,000 light-years away (on the other side of the Milky Way) and is one of the longest structures ever observed in our galaxy.

Continue reading “Astronomers Find the Biggest Structure in the Milky Way: Filament of Hydrogen 3,900 Light-Years Long” »

Yakir Aharonov and David Bohm proposed the effect that now bears their name in 1959, arguing that while classical potentials have no physical reality apart from the fields they represent, the same is not true in the quantum world. To make their case, the pair proposed a thought experiment in which an electron beam in a superposition of two wave packets is exposed to a time-varying electrical potential (but no field) when passing through a pair of metal tubes. They argued that the potential would introduce a phase difference between the wave packets and therefore lead to a measurable physical effect – a set of interference fringes – when the wave packets are recombined.

Seeking a gravitational counterpart

In the latest research, Mark Kasevich and colleagues at Stanford University show that the same effect also holds true for gravity. The platform for their experiment is an atom interferometer, which uses a series of laser pulses to split, guide and recombine atomic wave packets. The interference from these wave packets then reveals any change in the relative phase experienced along the two arms.

A quantum phenomenon predicted in 1959, the Aharonov-Bohm effect, also applies to gravity.

Most quantum computers are based on superconductors or trapped ions, but an alternative approach using ordinary atoms may have advantages.

Back in 2016, we told you about the iBubble, an underwater drone that autonomously follows and films scuba divers. Well, it now has a more capable industrial-use big brother, known as the Seasam.

‘Geometric frustration’ can cause the electrons in materials with atoms arranged in a triangular pattern to organize in three competing ways simultaneously, reveals a new computational study led by researchers at the Flatiron Institute.

Materials that look like mosaics of triangular tiles at the atomic level sometimes have paradoxical properties, and quantum physicists have finally found out why.

Using a combination of cutting-edge computational techniques, the scientists found that under special conditions, these triangular-patterned materials can end up in a mashup of three different phases at the same time. The competing phases overlap, with each wrestling for dominance. As a result, the material counterintuitively becomes more ordered when heated up, the scientists reported in Physical Review X.

An experiment, performed by Istituto Nazionale di Ricerca Metrologica (INRIM) on 200 km of the Italian Quantum Backbone, in collaboration with Toshiba Europe, shows that coherent laser interferometry considerably improves the performances of quantum key distribution protocols in long-distance, real-world networks. The study has been published in Nature Communications.

Quantum Key Distribution (QKD) protocols enable cryptographic keys to be shared between distant parties with an intrinsic security guaranteed by the laws of quantum mechanics. This is made possible by the transmission of single photons, the elementary particles of which light is made of.

The interest for this subject extends well beyond the scientific community, and has now a strong strategic and commercial relevance. The European Commission, within the “European Quantum Communication Infrastructure” intitative, aims at integrating quantum key distribution technologies into specific services throughout the European Union within the next 10 years, and INRIM will take part in the design of this infrastructure with the OQTAVO project.

A surprising property of how resonant photons interact with an absorbing medium has been uncovered by physicists in Canada. They say they have found that even photons passing straight through the medium energize atoms within it, causing atoms to spend nearly as much time in their excited states as those that have absorbed photons. They see their result as a challenge to theorists trying to describe how light interacts with matter quantum mechanically.

Aephraim Steinberg and colleagues at the University of Toronto made the discovery while investigating what happens to a beam of photons passing through a cloud of atoms when the photons’ frequency is equal to that of one of the atomic transitions. Intuitively, they say, it would be expected that those photons exciting atoms within the cloud would be absorbed and then at best re-emitted in a random direction. As such, the flux of photons coming from excited atoms that are detected in the forward direction would be miniscule.

Indeed, they point out, this idea that only absorbed, or “lost”, photons contribute to the excitation springs naturally from theory that tells us the total time atoms spend in the excited state is directly proportional to the number of photons that are lost.