Launch yourself from a great enough height and it won’t take long to see which would win in a battle between gravity and the forces that bind solid ground.
A team of scientists has detected the presence of a high-energy neutrino — a particularly elusive particle — in the wake of a star’s destruction as it is consumed by a black hole. This discovery, reported in the journal Nature Astronomy, sheds new light on the origins of Ultrahigh Energy Cosmic Rays — the highest energy particles in the Universe.
The work, which included researchers from more than two dozen institutions, including New York University and Germany’s DESY research center, focused on neutrinos — subatomic particles that are produced on Earth only in powerful accelerators.
Neutrinos — as well as the process of their creation — are hard to detect, making their discovery, along with that of Ultrahigh Energy Cosmic Rays (UHECRs), noteworthy.
Even in the world of the smallest particles with their own special rules, things cannot proceed infinitely fast. Physicists at the University of Bonn have now shown what the speed limit is for complex quantum operations. The study also involved scientists from MIT, the universities of Hamburg, Cologne and Padua, and the Jülich Research Center. The results are important for the realization of quantum computers, among other things. They are published in the prestigious journal Physical Review X, and covered by the Physics Magazine of the American Physical Society.
8 oct 2020.
MIT researchers using superconducting quantum bits connected to a microwave transmission line have shown how the qubits can generate on demand the photons, or particles of light, necessary for communication between quantum processors.
Two’s company, but three’s a crowd – unless you’re trying to make graphene superconduct at higher temperatures. That is the finding of researchers at Harvard University in the US, who discovered that the superconducting state in three stacked and twisted layers of graphene is more robust to temperature increase than the equivalent state in two-layer graphene. The researchers also found evidence that superconductivity in the trilayer system comes from strong interactions between electrons, rather than weak ones as in most conventional superconductors – corroborating a result reported a few days earlier by a separate team at the Massachusetts Institute of Technology (MIT).
A sheet of graphene consists of a simple repetition of carbon atoms arranged in a two-dimensional hexagonal lattice. When two sheets of graphene are placed atop each other and slightly misaligned, they form a moiré pattern, or “stretched” superlattice that dramatically changes the electronic interactions in the material compared to its pristine counterpart. The misalignment angle is critical: in 2018, the MIT group, led by Pablo Jarillo-Herrero, discovered a so-called “magic” angle of 1.1° where the material switches from an insulator to a superconductor. This means the twisted graphene can carry electrical current with no resistance below a superconducting transition temperature, Tc, of 1.7 K.
The cosmic microwave background, or CMB, is the electromagnetic echo of the Big Bang, radiation that has been traveling through space and time since the very first atoms were born 380000 years after our universe began. Mapping minuscule variations in the CMB tells scientists about how our universe came to be and what it’s made of.
When Light and Atoms Share a Common Vibe
An especially counter-intuitive feature of quantum mechanics is that a single event can exist in a state of superposition — happening both here and there, or both today and tomorrow.
Such superpositions are hard to create, as they are destroyed if any kind of information about the place and time of the event leaks into the surrounding — and even if nobody actually records this information. But when superpositions do occur, they lead to observations that are very different from that of classical physics, questioning down to our very understanding of space and time.
In the last decade, we’ve taken photos of a black holes, peered into the heart of atoms and looked back at the birth of the Universe. And yet, there are yawning gaps in our understanding of the Universe and the laws that govern it. These are the mysteries that will be troubling physicists and astronomers over the next decade and beyond.
Dark matter, the nature of time, aliens and supermassive black holes: these seven things will be puzzling astronomers for years to come.
Researchers unlocked the electronic properties of graphene by folding the material like origami paper.
Researchers at the US Department of Energy’s Princeton Plasma Physics Laboratory have created a plan using liquid lithium to control the extreme heat that could strike the exhaust system inside tokamak fusion reactors.
Continue reading “Scientists Use Lithium To Control Heat In Nuclear Fusion Reactors” »
Electrons in materials have a property known as ‘spin’, which is responsible for a variety of properties, the most well-known of which is magnetism. Permanent magnets, like the ones used for refrigerator doors, have all the spins in their electrons aligned in the same direction. Scientists refer to this behavior as ferromagnetism, and the research field of trying to manipulate spin as spintronics.
Down in the quantum world, spins can arrange in more exotic ways, giving rise to frustrated states and entangled magnets. Interestingly, a property similar to spin, known as “the valley,” appears in graphene materials. This unique feature has given rise to the field of valleytronics, which aims to exploit the valley property for emergent physics and information processing, very much like spintronics relies on pure spin physics.
