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Category: particle physics – Page 21
A strange quantum battery concept reveals the second law of entanglement
For more than a century, the laws of thermodynamics have helped us understand how energy moves, how engines work, and why time seems to flow in one direction. Now, researchers have made a similarly powerful discovery, but in the strange world of quantum physics.
Scientists have shown for the first time that entanglement, the mysterious link between quantum particles, can be reversibly manipulated just like heat or energy in a perfect thermodynamic cycle.
The researchers support their findings using a novel concept called an entanglement battery, which allows entanglement to flow in and out of quantum systems without being lost, much like a regular battery stores and supplies energy.
IceCube neutrino search sets first constraints on proton fraction of ultrahigh-energy cosmic rays
Neutrinos are subatomic particles with no charge and very little mass that are known to weakly interact with other matter in the universe. Due to their weak interactions with other particles, these particles are notoriously difficult to detect.
A class of neutrinos that has so far proved particularly elusive to detection methods are extremely-high-energy neutrinos, which have energies above 1016 electronvolts (eV). Physical theories suggest that these neutrinos would be produced from very energy-intensive astrophysical phenomena, such as interactions of ultrahigh-energy cosmic rays.
The IceCube Collaboration, a large group of researchers based at various research institutes worldwide, has been searching for extremely-high-energy neutrinos for over a decade. Their most recent findings, published in Physical Review Letters, set constraints on the proportion of protons in ultrahigh-energy cosmic rays, for the first time relying on data collected at the IceCube observatory, while also placing limits on the diffuse flux of extremely-high-energy neutrinos.
Famous double-slit experiment holds up when stripped to its quantum essentials
MIT physicists have performed an idealized version of one of the most famous experiments in quantum physics. Their findings demonstrate, with atomic-level precision, the dual yet evasive nature of light. They also happen to confirm that Albert Einstein was wrong about this particular quantum scenario.
The experiment in question is the double-slit experiment, which was first performed in 1801 by the British scholar Thomas Young to show how light behaves as a wave. Today, with the formulation of quantum mechanics, the double-slit experiment is now known for its surprisingly simple demonstration of a head-scratching reality: that light exists as both a particle and a wave. Stranger still, this duality cannot be simultaneously observed. Seeing light in the form of particles instantly obscures its wave-like nature, and vice versa.
The original experiment involved shining a beam of light through two parallel slits in a screen and observing the pattern that formed on a second, faraway screen. One might expect to see two overlapping spots of light, which would imply that light exists as particles, a.k.a. photons, like paintballs that follow a direct path. But instead, the light produces alternating bright and dark stripes on the screen, in an interference pattern similar to what happens when two ripples in a pond meet. This suggests light behaves as a wave. Even weirder, when one tries to measure which slit the light is traveling through, the light suddenly behaves as particles and the interference pattern disappears.
The Uncertainty Principle
Quantum mechanics is generally regarded as the physical theory that is our best candidate for a fundamental and universal description of the physical world. The conceptual framework employed by this theory differs drastically from that of classical physics. Indeed, the transition from classical to quantum physics marks a genuine revolution in our understanding of the physical world.
One striking aspect of the difference between classical and quantum physics is that whereas classical mechanics presupposes that exact simultaneous values can be assigned to all physical quantities, quantum mechanics denies this possibility, the prime example being the position and momentum of a particle. According to quantum mechanics, the more precisely the position (momentum) of a particle is given, the less precisely can one say what its momentum (position) is. This is (a simplistic and preliminary formulation of) the quantum mechanical uncertainty principle for position and momentum. The uncertainty principle played an important role in many discussions on the philosophical implications of quantum mechanics, in particular in discussions on the consistency of the so-called Copenhagen interpretation, the interpretation endorsed by the founding fathers Heisenberg and Bohr.
This should not suggest that the uncertainty principle is the only aspect of the conceptual difference between classical and quantum physics: the implications of quantum mechanics for notions as (non)-locality, entanglement and identity play no less havoc with classical intuitions.
Good vibrations: Scientists use imaging technology to visualize heat
Most people envision vibration on a large scale, like the buzz of a cell phone notification or the oscillation of an electric toothbrush. But scientists think about vibration on a smaller scale—atomic, even.
In a first for the field, researchers from The Grainger College of Engineering at the University of Illinois at Urbana-Champaign have used advanced imaging technology to directly observe a previously hidden branch of vibrational physics in 2D materials. Their findings, published in Science, confirm the existence of a previously unseen class of vibrational modes and present the highest resolution images ever taken of a single atom.
Two-dimensional materials are a promising candidate for next-generation electronics because they can be scaled down in size to thicknesses of just a few atoms while maintaining desirable electronic properties. A route to these new electronic devices lies at the atomic level, by creating so-called Moiré systems—stacks of 2D materials whose lattices do not match, for reasons such as the twisting of atomic layers.
Engineers overcome radiation challenge with custom silicon chips
The Large Hadron Collider (LHC) is tough on electronics. Situated inside a 17-mile-long tunnel that runs in a circle under the border between Switzerland and France, this massive scientific instrument accelerates particles close to the speed of light before smashing them together. The collisions yield tiny maelstroms of particles and energy that hint at answers to fundamental questions about the building blocks of matter.
Those collisions produce an enormous amount of data—and enough radiation to scramble the bits and logic inside almost any piece of electronic equipment.
That presents a challenge to CERN’s physicists as they attempt to probe deeper into the mysteries of the Higgs boson and other fundamental particles. Off-the-shelf components simply can’t survive the harsh conditions inside the accelerator, and the market for radiation-resistant circuits is too small to entice investment from commercial chip manufacturers.
NASA Is Watching a Huge Anomaly Growing in Earth’s Magnetic Field
For years, NASA has monitored a strange anomaly in Earth’s magnetic field: a giant region of lower magnetic intensity in the skies above the planet, stretching out between South America and southwest Africa.
This vast, developing phenomenon, called the South Atlantic Anomaly, has intrigued and concerned scientists for years, and perhaps none more so than NASA researchers.
The space agency’s satellites and spacecraft are particularly vulnerable to the weakened magnetic field strength within the anomaly, and the resulting exposure to charged particles from the Sun.