Lifeboat Foundation

Hydrogen, the most abundant element in the universe, is found everywhere from the dust filling most of outer space to the cores of stars to many substances here on Earth. This would be reason enough to study hydrogen, but its individual atoms are also the simplest of any element with just one proton and one electron. For David Ceperley, a professor of physics at the University of Illinois Urbana-Champaign, this makes hydrogen the natural starting point for formulating and testing theories of matter.

Ceperley, also a member of the Illinois Quantum Information Science and Technology Center, uses computer simulations to study how hydrogen atoms interact and combine to form different phases of matter like solids, liquids, and gases. However, a true understanding of these phenomena requires quantum mechanics, and quantum mechanical simulations are costly. To simplify the task, Ceperley and his collaborators developed a machine learning technique that allows quantum mechanical simulations to be performed with an unprecedented number of atoms. They reported in Physical Review Letters that their method found a new kind of high-pressure solid hydrogen that past theory and experiments missed.

“Machine learning turned out to teach us a great deal,” Ceperley said. “We had been seeing signs of new behavior in our previous simulations, but we didn’t trust them because we could only accommodate small numbers of atoms. With our machine learning model, we could take full advantage of the most accurate methods and see what’s really going on.”

Providing increased resistance to outside interference, topological qubits create a more stable foundation than conventional qubits. This increased stability allows the quantum computer to perform computations that can uncover solutions to some of the world’s toughest problems.

While qubits can be developed in a variety of ways, the topological qubit will be the first of its kind, requiring innovative approaches from design through development. Materials containing the properties needed for this new technology cannot be found in nature—they must be created. Microsoft brought together experts from condensed matter physics, mathematics, and materials science to develop a unique approach producing specialized crystals with the properties needed to make the topological qubit a reality.

Researchers at The University of Manchester have discovered record-high magnetoresistance in graphene.

Graphene is an allotrope of carbon in the form of a single layer of atoms in a two-dimensional hexagonal lattice in which one atom forms each vertex. It is the basic structural element of other allotropes of carbon, including graphite, charcoal, carbon nanotubes, and fullerenes. In proportion to its thickness, it is about 100 times stronger than the strongest steel.

But we expect that it’s in that first tiny fraction of a second that the key features of our universe were imprinted.

The conditions of the universe can be described through its “fundamental constants”—fixed quantities in nature, such as the gravitational constant (called G) or the speed of light (called C). There are about 30 of these representing the sizes and strengths of parameters such as particle masses, forces, or the universe’s expansion. But our theories don’t explain what values these constants should have. Instead, we have to measure them and plug their values into our equations to accurately describe nature.

Continue reading “The Multiverse: Our Universe Is Suspiciously Unlikely to Exist—Unless It Is One of Many” »

Wearable devices like Spiderman’s suit that are thin and soft, yet also feature electrical and optical functionalities? The answer lies in producing novel materials that go far beyond the performance of existing materials and developing technology that enables the precise control of the physical properties of such materials.

Separating transition metal dichalcogenide (TMD) into a single layer just like graphene makes it transform into a thin, two-dimensional (2D) film material that exhibits the characteristics of highly performing semiconductors. By stacking two disparate TMD layers, different combinations of TMD types and stacking methods can produce unique properties.

For this reason, 2D semiconductors based on heterostructures are attracting attention as an important next-generation material for the electronics industry throughout academia and industries around the world. However, it is still quite challenging to commercialize them due to the difficulty of controlling with precision the physical properties of their quasiparticles.

Where did all the antimatter go? After the Big Bang, matter and antimatter should have been created in equal amounts. Why we live in a universe of matter, with very little antimatter, remains a mystery. The excess of matter could be explained by the violation of charge-parity (CP) symmetry, which essentially means that certain processes that involve particles behave differently to those that involve their antiparticles.

However, the CP-violating processes that have been observed so far are insufficient to explain the matter–antimatter asymmetry in the universe. New sources of CP violation must be out there—and might be hiding in interactions involving the Higgs boson. In the Standard Model of particle physics, Higgs-boson interactions with other particles conserve CP symmetry. If researchers find signs of CP violation in these interactions, they could be a clue to one of the universe’s oldest mysteries.

In a new analysis of its full dataset from Run 2 of the LHC, the ATLAS collaboration tested the Higgs-boson interactions with the carriers of the weak force, the W and Z bosons, looking for signs of CP violation. The collaboration studied Higgs-boson decays into two Z bosons, each of which transforms into a pair of leptons (an electron and a positron or a muon and an antimuon), thus resulting in four charged leptons. The researchers also studied interactions in which two W or Z bosons combine to produce a Higgs boson. In this case, one quark and one antiquark are produced together with the Higgs boson, creating ‘jets’ of particles in the ATLAS detector.

A giant orbital magnetic moment exists in graphene quantum dots, according to new work by physicists at the University of California Santa Cruz in the US. As well as being of fundamental interest for studying systems with relativistic electrons – that is those travelling at near-light speeds – the work could be important for quantum information science since these moments could encode information.

Graphene, a sheet of carbon just one atom thick, has a number of unique electronic properties, many of which arise from the fact that it is a semiconductor with a zero-energy gap between its valence and conduction bands. Near where the two bands meet, the relationship between the energy and momentum of charge carriers (electrons and holes) in the material is described by the Dirac equation and resembles that of a photon, which is massless.

These bands, called Dirac cones, enable the charge carriers to travel through graphene at extremely high, “ultra-relativistic” speeds approaching that of light. This extremely high mobility means that graphene-based electronic devices such as transistors could be faster than any that exist today.

The DarkSide experiment is an ambitious research effort aimed at detecting dark matter particle interactions in liquid argon using a dual-phase physics detector located at the underground Gran Sasso National Laboratory. These interactions could be observed by minimizing background signals, and this could be possible thanks to the remarkable discrimination power of the scintillation pulse of liquefied argon in the DarkSide-50 detector, which can separate nuclear recoil events associated with these interactions from more than 100 million electronic recoil events linked to radioactive background.

The large team of researchers involved in the DarkSide experiment has recently been using the detector to search for lighter dark matter particles. The results of a new search for dark matter–nucleon interactions, published in Physical Review Letters, allowed them to set new constraints for sub-GeV/c² dark matter.

“The DarkSide-50 experiment was designed as a test for the use of argon from underground sources, naturally depleted in the radioactive ³⁹ Ar, for very large scale dark matter searches,” Cristiano Galbiati a Researcher at Princeton University and the Gran Sasso Science Institute, told Phys.org. “It is remarkable to see how a group of young researchers within the collaboration was able to exploit the apparatus to extract the best limit for dark matter searches that were not part of the original scope of the experiment. If anything, the ingenuity and resolve of this group should be credited for this important result.”

Even if you are not a quantum physicist, you will most likely have heard of Schrödinger’s famous cat. Erwin Schrödinger came up with the feline that can be alive and dead at the same time in a thought experiment in 1935. The obvious contradiction—after all, in everyday life we only ever see cats that are either alive or dead—has prompted scientists to try to realize analogous situations in the laboratory. So far, they have managed to do so using, for instance, atoms or molecules in quantum mechanical superposition states of being in two places at the same time.

At ETH, a team of researchers led by Yiwen Chu, professor at the Laboratory for Solid State Physics, has now created a substantially heavier Schrödinger cat by putting a small crystal into a superposition of two oscillation states. Their results, which have been published this week in the journal Science, could lead to more robust quantum bits and shed light on the mystery of why quantum superpositions are not observed in the macroscopic world.

In Schrödinger’s original thought experiment, a cat is locked up inside a metal box together with a radioactive substance, a Geiger counter and a flask of poison. In a certain time-frame—an hour, say—an atom in the substance may or may not decay through a quantum mechanical process with a certain probability, and the decay products might cause the Geiger counter to go off and trigger a mechanism that smashes the flask containing the poison, which would eventually kill the cat.