Delayed Big Bang for dark matter could be detected in gravitational waves

30 Nov 2024

Energy transition Dark matter may have been created after the Big Bang, something that could soon be tested by gravitational wave detectors. (Courtesy: Shutterstock/Tomertu)

New constraints on a theory that says dark matter was created just after the Big Bang – rather than at the Big Bang – have been determined by Richard Casey and Cosmin Ilie at Colgate University in the US. The duo calculated the full range of parameters in which a “Dark Big Bang” could fit into the observed history of the universe. They say that evidence of this delayed creation could be found in gravitational waves.

Dark matter is a hypothetical substance that is believed to play an important role in the structure and dynamics of the universe. It appears to account for about 27% of the mass–energy in the cosmos and is part of the Standard Model of cosmology. However, dark matter particles have never been observed directly.

 

Quantum error correction research yields unexpected quantum gravity insights

21 Nov 2024 Han Le

Quantum link: New research has revealed an unexpected connection between the physics of approximate error-correcting codes and quantum gravity. (Courtesy: Shutterstock/Evgenia Fux)

In computing, quantum mechanics is a double-edged sword. While computers that use quantum bits, or qubits, can perform certain operations much faster than their classical counterparts, these qubits only maintain their quantum nature – their superpositions and entanglement – for a limited time. Beyond this so-called coherence time, interactions with the environment, or noise, lead to loss of information and errors. Worse, because quantum states cannot be copied – a consequence of quantum mechanics known as the no-cloning theorem – or directly observed without collapsing the state, correcting these errors requires more sophisticated strategies than the simple duplications used in classical computing.

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by KONSTANTINOS TSIANTIS (Author)  Format: Kindle Edition

Unlock the secrets of successful negotiations in a world where every interaction counts. "Focus on Systemic Negotiations" is a transformative guide for anyone seeking to excel in negotiations, regardless of their experience level. This compelling book equips beginners with foundational skills and empowers seasoned negotiators to refine their techniques in complex multicultural environments. Are you ready to elevate your negotiation game and confidently navigate even the trickiest personalities?

 

Thorium Fuel Cycle Introduction

 

Orbital angular momentum monopoles appear in a chiral crystal

23 Oct 2024 Isabelle Dumé

Monopoles of orbital angular momentum (OAM) are a tantalizing prospect for orbitronics because OAM is uniform in all directions. This would mean that information flows could be generated in any direction. Visualizing the orbital texture is almost like capturing an image of the OAM monopoles. (Courtesy: Paul Scherrer Institute / Monika Bletry)

Magnets generally have two poles, north and south, so observing something that behaves like it has only one is extremely unusual. Physicists in Germany and Switzerland have become the latest to claim this rare accolade by making the first direct detection of structures known as orbital angular momentum monopoles. The monopoles, which the team identified in materials known as chiral crystals, had previously only been predicted in theory. The discovery could aid the development of more energy-efficient memory devices.

Traditional electronic devices use the charge of electrons to transfer energy and information. This transfer process is energy-intensive, however, so scientists are looking for alternatives. One possibility is spintronics, which uses the electron’s spin rather than its charge, but more recently another alternative has emerged that could be even more promising. Known as orbitronics, it exploits the orbital angular momentum (OAM) of electrons as they revolve around an atomic nucleus. By manipulating this OAM, it is in principle possible to generate large magnetizations with very small electric currents – a property that could be used to make energy-efficient memory devices.

 

Negative triangularity tokamaks: a power plant plasma solution from the core to the edge?

22 Oct 2024 Sponsored by Plasma Physics and Controlled Fusion

Available to watch now, IOP Publishing’s journal, Plasma Science and Technologies explores the knowns and unknowns of negative triangularity and evaluate its future as a power plant solution

The webinar is directly linked with a special issue of Plasma Physics and Controlled Fusion on Advances in the Physics Basis of Negative Triangularity Tokamaks; featuring contributions from all of the speakers, and many more papers from the leading groups researching this fascinating topic.

Want to learn more on this subject?

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In recent years the fusion community has begun to focus on the practical engineering of tokamak power plants. From this, it became clear that the power exhaust problem, extracting the energy produced by fusion without melting the plasma-facing components, is just as important and challenging as plasma confinement. To these ends, negative triangularity plasma shaping holds unique promise.

Conceptually, negative triangularity is simple. Take the standard positive triangularity plasma shape, ubiquitous among tokamaks, and flip it so that the triangle points inwards. By virtue of this change in shape, negative triangularity plasmas have been experimentally observed to dramatically improve energy confinement, sometimes by more than a factor of two. Simultaneously, the plasma shape is also found to robustly prevent the transition to the improved confinement regime H-mode. While this may initially seem a drawback, the confinement improvement can enable negative triangularity to still achieve similar confinement to a positive triangularity H-mode. In this way, it robustly avoids the typical difficulties of H-mode: damaging edge localized modes (ELMs) and the narrow scrape-off layer (SOL) width. This is the promise of negative triangularity, an elegant and simple path to alleviating power exhaust while preserving plasma confinement.

 

Multi-qubit entangled states boost atomic clock and sensor performance

22 Oct 2024

Coloradans Left to right are Adam Kaufman, Nelson Darkwah Oppong, Alec Cao and Theo Lukin Yelin. They are inspecting an atomic optical clock at JILA. (Courtesy: Patrick Campbell/CU Boulder)

Frequency measurements using multi-qubit entangled states have been performed by two independent groups in the US. These entangled states have correlated errors, resulting in measurement precisions better than the standard quantum limit. One team is based in Colorado and it measured the frequency of an atomic clock with greater precision than possible using conventional methods. The other group is in California and it showed how entangled states could be used in quantum sensing.

Atomic clocks are the most accurate timekeeping devices we have. They work by locking an ultraprecise, frequency comb laser to a narrow linewidth transition in an atom. The higher the transition’s frequency, the faster the clock ticks and the more precisely it can keep time. The clock with the best precision today is operated by Jun Ye’s group at JILA in Boulder, Colorado and colleagues. After running for the age of the universe, this clock would only be wrong by 0.01 s.