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Category: particle physics – Page 117

Neutron Star Collisions: Unmasking the Ghosts of Gravity

Scientists are using advanced simulations to explore the aftermath of neutron star collisions, where remnants might form and avoid collapsing into black holes.

This research not only sheds light on the dynamics and cooling of these remnants through neutrino emissions but also provides crucial insights into the behavior of nuclear matter under extreme conditions. The findings contribute to our understanding of astronomical events and the conditions that may or may not lead to black hole formation.

Mysterious aftermath of neutron star collisions.

Hosting the Universe in a Quantum Computer: Scientists Simulate Cosmological Particle Creation

The foundation of this simulation, as described by the team, is a well-known cosmological model that describes the universe as expanding uniformly over time. The researchers modeled how a quantum field, initially in a vacuum state (meaning no particles are present), responds to this expansion. As spacetime stretches, the field’s oscillations mix in a process that can create particles where none previously existed. This phenomenon is captured by a transformation that relates the field’s behavior before and after the universe expands, showing how vibrations at different momenta become entangled, leading to particle creation.

To understand how many particles are generated, the researchers used a mathematical tool called the Bogoliubov transformation. This approach describes how the field’s vacuum state evolves into a state where particles can be detected. As the expansion rate increases, more particles are produced, aligning with predictions from quantum field theory. By running this simulation on IBM quantum computers, the team was able to estimate the number of particles created and observe how the quantum field behaves during the universe’s expansion, offering a new way to explore complex cosmological phenomena.

According to the team, the most notable result of the study was the ability to estimate the number of particles created as a function of the expansion rate of the universe. By running their quantum circuit on both simulators and IBM’s 127-qubit Eagle quantum processor, the researchers demonstrated that they could successfully simulate particle creation in a cosmological context. While the results were noisy—particularly for low expansion rates—the error mitigation techniques used helped bring the outcomes closer to theoretical predictions.

Unlocking Efficiency: How Ultra-Smooth Surfaces Improve Particle Accelerators

A new toolkit helps monitor and improve the efficiency of superconducting radiofrequency cavities in particle accelerators by ensuring smoother inner surfaces and analyzing impurities in niobium cavities.

Superconducting radiofrequency (SRF) cavities are essential to the function of advanced particle accelerators. They are a key part of the systems that power the electromagnetic fields that accelerate subatomic particles. The efficiency of these cavities is influenced by the cleanliness, shape, and smoothness of their inner surfaces.

Enhancing SRF Cavities with New Toolkits.

Space Emerging from Quantum Mechanics

Planck length and Planck time and quantum foam.

Space Emerging from Quantum.

The other day I was amused to find a quote from Einstein, in 1936, about how hard it would be to quantize gravity: “like an attempt to breathe in empty space.” Eight decades later, I think we can still agree that it’s hard.

So here is a possibility worth considering: rather than quantizing gravity, maybe we should try to gravitize quantum mechanics. Or, more accurately but less evocatively, “find gravity inside quantum mechanics.” Rather than starting with some essentially classical view of gravity and “quantizing” it, we might imagine starting with a quantum view of reality from the start, and find the ordinary three-dimensional space in which we live somehow emerging from quantum information. That’s the project that ChunJun (Charles) Cao, Spyridon (Spiros) Michalakis, and I take a few tentative steps toward in a new paper.

We human beings, even those who have been studying quantum mechanics for a long time, still think in terms of a classical concepts. Positions, momenta, particles, fields, space itself. Quantum mechanics tells a different story. The quantum state of the universe is not a collection of things distributed through space, but something called a wave function. The wave function gives us a way of calculating the outcomes of measurements: whenever we measure an observable quantity like the position or momentum or spin of a particle, the wave function has a value for every possible outcome, and the probability of obtaining that outcome is given by the wave function squared. Indeed, that’s typically how we construct wave functions in practice. Start with some classical-sounding notion like “the position of a particle” or “the amplitude of a field,” and to each possible value we attach a complex number.

Decoherence by warm horizons

Recently Danielson, Satishchandran, and Wald (DSW) have shown that quantum superpositions held outside of Killing horizons will decohere at a steady rate. This occurs because of the inevitable radiation of soft photons (gravitons), which imprint a electromagnetic (gravitational) “which-path’’ memory onto the horizon. Rather than appealing to this global description, an experimenter ought to also have a local description for the cause of decoherence. One might intuitively guess that this is just the bombardment of Hawking/Unruh radiation on the system, however simple calculations challenge this idea—the same superposition held in a finite temperature inertial laboratory does not decohere at the DSW rate. In this work we provide a local description of the decoherence by mapping the DSW setup onto a worldline-localized model resembling an Unruh-DeWitt particle detector.

Linus Pauling Was Right: Scientists Confirm Century-Old Electron Bonding Theory

A breakthrough study has validated the existence of a stable single-electron covalent bond between two carbon atoms, supporting Linus Pauling’s early 20th-century theory and opening avenues for chemical research.

Covalent bonds, in which two atoms share a pair of electrons, form the foundation of most organic compounds. In 1931, the Nobel Laureate Linus Pauling suggested that covalent bonds made from just a single, unpaired electron could exist, but these single-electron bonds would likely be much weaker than a standard covalent bond involving a pair of electrons.

Since then, single-electron bonds have been observed, but never in carbon or hydrogen. The search for one-electron bonds shared between carbon atoms has stymied scientists.

Engineers create a chip-based tractor beam for biological particles

Traditional , which trap and manipulate particles using light, usually require bulky microscope setups, but chip-based optical tweezers could offer a more compact, mass manufacturable, broadly accessible, and high-throughput solution for in biological experiments.

However, other similar integrated optical tweezers can only capture and manipulate cells that are very close to or directly on the chip surface. This contaminates the chip and can stress the cells, limiting compatibility with standard biological experiments.

Using a system called an integrated optical phased array, the MIT researchers have developed a new modality for integrated optical tweezers that enables trapping and tweezing of cells more than a hundred times further away from the chip surface.

New materials and techniques show promise for microelectronics and quantum technologies

The next generation of handheld devices requires a novel solution. Spintronics, or , is a revolutionary new field in condensed-matter physics that can increase the memory and logic processing capability of nano-electronic devices while reducing power consumption and production costs. This is accomplished by using inexpensive materials and the magnetic properties of an electron’s spin to perform memory and logic functions instead of using the flow of electron charge used in typical electronics.

New work by Florida State University scientists is propelling spintronics research forward.

Professors Biwu Ma in the Department of Chemistry and Biochemistry and Peng Xiong in the Department of Physics work with low-dimensional organic metal halide hybrids, a new class of hybrid materials that can power optoelectronic devices like solar cells, light-emitting diodes, or LEDs and photodetectors.

Evidence of ‘Negative Time’ Found in Quantum Physics Experiment

Physicists showed that photons can seem to exit a material before entering it, revealing observational evidence of negative time.

By Manon Bischoff & Jeanna Bryner

Quantum physicists are familiar with wonky, seemingly nonsensical phenomena: atoms and molecules sometimes act as particles, sometimes as waves; particles can be connected to one another by a “spooky action at a distance,” even over great distances; and quantum objects can detach themselves from their properties like the Cheshire Cat from Alice’s Adventures in Wonderland detaches itself from its grin. Now researchers led by Daniela Angulo of the University of Toronto have revealed another oddball quantum outcome: photons, wave-particles of light, can spend a negative amount of time zipping through a cloud of chilled atoms. In other words, photons can seem to exit a material before entering it.