Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: particle physics – Page 7

Cosmic lockdown: How the environment can isolate quantum fields

A simplified cosmological model suggests that decoherence can suppress quantum tunneling, effectively locking fields into the vacuum state they have reached.

The vacuum is not always so empty. “When we talk about a vacuum in cosmology, we do not mean completely devoid of energy,” explains David Wands, Professor at the Institute of Cosmology & Gravitation at the University of Portsmouth. “A vacuum is rather a state in which a field sits at a minimum of its energy. The true vacuum is the lowest possible minimum, but there can also be local minima, which we call false vacua.” We can picture this as a landscape made up of valleys of different depths: the true vacuum is the deepest one, while the others are false vacua.

Something sitting in one of these depressions can remain “trapped” there even if, somewhere else, a lower-energy state exists. This is exactly what can happen to quantum fields, fundamental physical objects that permeate the universe. A classical field is something that has a value at every position in space, like a magnetic field, whose strength changes from point to point. Quantum fields behave in a similar way, and their excitations appear as particles.

One-atom-high rails steer superconducting vortices, with temperature and magnetic field tuning their guidance

Researchers at the Research Center for Materials Nanoarchitectonics (MANA), a center within Japan’s National Institute for Materials Science (NIMS), discovered that atomic-scale steps can guide superconducting vortices in an ultrathin superconductor.

Vortices moved more than 1,000 times as easily along the steps as across them, and this guiding effect could be tuned by temperature and magnetic field.

Superconducting vortices are tiny quantum objects whose movement can strongly influence how superconductors behave. Controlling their direction of motion could therefore be important for developing ultralow-power superconducting technologies.

Jupiter Handles the Solar Wind in a Way Scientists Didn’t Expect

New observations from NASA’s Juno mission are revealing that Jupiter’s bow shock behaves in more complex ways than its counterpart at Earth.

NASA’s Juno spacecraft has captured the most detailed measurements yet of Jupiter’s bow shock, the vast boundary where the solar wind crashes into the planet’s magnetic environment. The observations show that Jupiter manages this high-energy interaction very differently from Earth, using a more complex mix of plasma waves and smaller shock structures to slow incoming particles.

The results, reported by a University of Iowa-led team, also give researchers a nearby example of shock physics that could help them study far more energetic environments, including the remnants of exploded stars.

Quantum device simulates matter popping into existence

A research team led by faculty at the Duke Quantum Center (DQC) has observed string-breaking dynamics related to particle-antiparticle formation on a quantum simulator, among the first such observations in quantum physics.

The approach, described in the journal Nature Physics, shows that trapped-ion quantum computers can be used to probe fundamental questions about the universe. The experiment emulates string-breaking, a phenomenon in which two connected fundamental building blocks of matter stretch apart, building up enough energy that new particles “pop into existence” when the connection snaps.

“Quantum computer simulations provide the best platform to investigate complex questions like matter formation, short of having witnessed the Big Bang itself,” said Christopher Monroe, the Gilhuly Family Presidential Distinguished Professor of Electrical and Computer Engineering and Physics at Duke, who led the research.

Spin waves inside a nano-oscillator imaged for the first time

For the first time, researchers have directly imaged the magnetization dynamics inside a spin Hall nano-oscillator—a nanoscale device that converts direct current into tunable microwave signals and is a promising building block for energy-efficient wireless communication and brain-inspired computing.

A Swedish–German team led by the University of Gothenburg and Helmholtz-Zentrum Berlin (HZB) achieved this using time-resolved scanning transmission X-ray microscopy at the MAXYMUS instrument at BESSY II. The results, published in Advanced Materials, reveal spin-wave features that had escaped previous indirect measurement techniques.

Spin Hall nano-oscillators (SHNOs) are among the most versatile devices in spintronics: A direct current driven through a nanometer-sized constriction sets the local magnetization into steady precession, turning a DC input into a tunable radio-frequency output.

Physicists Tackle a Classic Quantum Problem With a Powerful New Computational Method

A new computational approach uses the real electronic structure of materials to predict a classic quantum effect far more accurately than simplified models.

Seven magnetic atoms embedded one at a time in copper have given physicists a new way to test whether computers can predict the behavior of real quantum materials without first reducing them to simplified models.

For most of the seven transition-metal impurities, calculations developed by researchers at Caltech and Yale University improved on the accuracy of conventional model-based predictions by as much as two orders of magnitude. The test involved the Kondo effect, a classic quantum problem whose general physics has been understood for decades even though its precise behavior in specific materials has remained difficult to calculate.

What happens when a particle breaks apart? | Cenke Xu (UCSB)

The purpose of these Blackboard Talk lunches is for the science of one program to be explained to the other KITP program participants. These talks lead to cross program communications that work towards our goal of maintaining the unity of theoretical physics.

Connect with KITP everywhere:

https://twitter.com/@kitp_ucsb.
https://kitp-ucsb.bsky.social.
▶ / @kitp_ucsb.
/ kavli-institute-for-theoretical-physics.

The position of the KITP is that ownership and copyright of all online material — slides, text, audio, video, and podcasts — belongs to the author. KITP is providing dissemination for these materials but does not claim ownership. Any person citing these materials for scholarly purposes should provide an appropriate scholarly reference.

/* */