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Category: particle physics – Page 276

Crazy Ants Behave like Active Swimmers

Without verbal communication, a group of 100 longhorn crazy ants can simultaneously grab onto an object 10,000 times their weight and collectively walk it to their nest. Scientists understand the ant-behavioral rules behind this feat but have lacked a coarse-grained description of how the group moves. Tabea Heckenthaler of the Weizmann Institute of Science in Israel and her colleagues now provide that description, showing that it fits expectations for a self-propelled particle [1]. The finding offers a simplified route to modeling complex systems.

When a foraging ant happens upon a tasty morsel too big to carry alone, she recruits other ants via a pheromone trail. When enough helpers are gathered, they grab on with their mouths and move the object toward home. Ants at the front pull the load, while those at the back lift to reduce friction. From studies of individual ants, scientists have gleaned other details; for example, after an ant grabs on, she spends around 10 seconds pulling in what she thinks is the direction of the nest—regardless of the group’s actual direction—before aligning her efforts with the other workers. There is also a constant turnover of workers, with ants dropping off and new ants immediately filling gaps.

Instead of accounting for such individual behaviors, Heckenthaler and her colleagues consider the ants and the food item as a single moving system. From experiments performed with a cog-shaped load coated in cat food (to encourage the ants), they find that the ant-load system follows trajectories similar to the directed walks of individual self-propelled particles. Comparing trajectories of cogs carried by different numbers of ants, the researchers then show that they can work out details of the ants’ individual behavior from the group-level measurements.

This new quantum ruler will help set electrical standards

“Using the new quantum ruler to study how the circular orbits vary with magnetic field, we hope to reveal the subtle magnetic properties of these moiré quantum materials”

Graphene, a single-atom-thick sheet of carbon, is renowned for its exceptional electrical conductivity and mechanical strength.

However, when two or more layers of graphene are stacked with a slight misalignment, they become moiré quantum matter, opening the door to a world of exotic possibilities. Depending on the angle of twist, these materials can generate magnetic fields, become superconductors with zero electrical resistance, or transform into perfect insulators.

Researchers catch protons in the act of dissociation with ultrafast ‘electron camera’

Scientists have caught fast-moving hydrogen atoms—the keys to countless biological and chemical reactions—in action.

A team led by researchers at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University used ultrafast electron diffraction (UED) to record the motion of hydrogen atoms within ammonia molecules. Others had theorized they could track hydrogen atoms with electron diffraction, but until now nobody had done the experiment successfully.

The results, published in Physical Review Letters, leverage the strengths of high-energy Megaelectronvolt (MeV) electrons for studying hydrogen atoms and proton transfers, in which the singular proton that makes up the nucleus of a hydrogen atom moves from one molecule to another.

Ways to weigh a neutrino

In 1980, Hamish Robertson was a tenured professor at Michigan State. He’d been there since his postdoc in 1971, and he was content. “I want to stress how valued and happy I felt there,” he says. “It was, and still is, an outstanding place.”

But he and his friend and colleague, Tom Bowles, had begun to hatch an idea that would take him far from MSU. They were devising a new experiment to measure the mass of the elusive and perplexingly light neutrino.

Neutrinos are the only fundamental particles whose mass we still don’t know. As their name implies, neutrinos are very, very small. But they outnumber the other fundamental particles by a factor of 10 billion.

The First Quantum Engine Is Here And It Could Power A Revolution

In a schematic view, an engine uses a thermodynamic change to produce work. For example, when a gas is ignited, it expands and so pushes a piston. Now, researchers have been able to develop a similar kind of engine but instead of using the relationship between temperature, pressure, and volume, the new device uses quantum mechanics.

The quantum engine employs a gas that can turn from a fermion gas to a boson gas. Fermions and bosons are a way to divide all particles into two categories. Their difference comes from a property called spin, an intrinsic angular momentum. Fermions have a fractional value (1÷2, 3/2) while bosons have integer spin (0, 1, 2, …).

There is another difference that matters in the engine too: the Pauli exclusion principle. And this only applies to fermions.

Scientists create a novel quantum platform using atoms

The method is still at its basic stage but multiple such microscopes could be pooled up to build a larger quantum computer.

Researchers at the IBS Center for Quantum Nanoscience (QNS) in Seoul, South Korea, have successfully demonstrated using a scanning tunneling microscope (STM) to perform quantum computation using electrons as qubits, a press release said.

Quantum computing is usually associated with terms such as atom traps or superconductors that aid in isolating quantum states or qubits that serve as a basic unit of information. In many ways, everything in nature is quantum and can be used to perform quantum computations as long as we can isolate its quantum states.

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