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Category: particle physics – Page 2

Building desktop particle accelerators to unlock new realms of research

Using high-intensity lasers, researchers have taken an important step toward miniaturization of particle accelerators by demonstrating free-electron laser amplification at extreme ultraviolet wavelengths (27–50 nm), with an acceleration length of only a few millimeters. By generating high-quality, monoenergetic electron beams (i.e. beams where all the electrons have nearly the same energy), they have achieved a key milestone toward compact accelerator technologies.

The work is published in the journal Physical Review Research.

The research team led by The University of Osaka’s Institute of Scientific and Industrial Research (SANKEN) in collaboration with Kansai Institute for Photon Science (KPSI), National Institutes for Quantum Science and Technology (QST), RIKEN SPring-8 Center (RSC), High Energy Accelerator Research Organization (KEK), used a technique called laser wakefield acceleration to create plasma waves that generate extremely strong accelerating electric fields, thanks to waves within the plasma that travel at almost the speed of light.

Useful quantum computers could be built with as few as 10,000 qubits, team finds

Quantum computers of the future may be closer to reality thanks to new research from Caltech and Oratomic, a Caltech-linked start-up company. Theorists and experimentalists teamed up to develop a new approach for reducing the errors that riddle today’s rudimentary quantum computers. Whereas these machines were previously thought to require millions of qubits to work properly (qubits being the quantum equivalent to 1’s and 0’s in classical computers), the new results indicate that a fully realized quantum computer could be built with as few as 10,000 to 20,000 qubits. The need for fewer qubits means that quantum computers could, in theory, be operational by the end of the decade.

The team proposes a new quantum error-correction architecture that is significantly more efficient than previous approaches. Quantum error correction is a process by which extra, redundant qubits are introduced to correct errors, or faults, enabling the ultimate goal in the field: fault-tolerant quantum computing.

The results exploit special properties of quantum computing platforms built out of neutral atoms, which serve as the qubits. Alternative platforms in development include superconducting circuits and trapped ions (ions are charged whereas neutral atoms are not). In a neutral atom system, laser beams known as optical tweezers are used to arrange atoms into qubit arrays. Manuel Endres, a professor of physics at Caltech, and his colleagues recently created the largest qubit array ever assembled, containing 6,100 trapped neutral atoms.

Gravitational waves as possible candidates for the origin of dark matter

Gravitational waves could be responsible for the production of dark matter during the early phases of our universe’s formation, according to results of a new study by Professor Joachim Kopp from Johannes Gutenberg University Mainz (JGU) and the PRISMA Cluster of Excellence in cooperation with Dr. Azadeh Maleknejad from Swansea University. Their work, published in Physical Review Letters, presents new calculations that explore a novel mechanism for the formation of dark matter through so-called stochastic gravitational waves.

In this way, they contribute to answering a fundamental question in particle physics. Planets, stars, and even life on Earth are all composed of visible matter. This type of matter only makes up about 4% of our universe. The vast majority is invisible, consisting of dark matter and dark energy. For instance, dark matter makes up about 23% of our universe.

Astrophysical observations confirm that dark matter permeates the whole universe and forms galaxies as well as the largest known structures in the cosmos. However, the particles that make up dark matter are still unknown. Many theories and ongoing experiments are looking for an answer to this open question.

Hidden features in X-rays could radically change how we measure and understand them

Hidden features uncovered in X-ray signals are set to overturn a key scientific theory and fundamentally change how X-rays are interpreted across fields of physics, chemistry, biology and materials science, new research reveals. Researchers say the discovery can help scientists measure X-rays more precisely and reliably, and improve our understanding of common materials, from battery materials to biological proteins.

X-ray science focuses on the unique energy signatures of atoms. These include the specific X-rays emitted when electrons transition into inner shells—the strongest of which are known as K-alpha lines—as well as distinct energy thresholds at which atoms begin to strongly absorb X-rays.

For more than 50 years, the entire field has relied on the assumption that a core parameter in the equation used to model X-ray absorption spectra, known as the standard XAFS equation, is fixed and does not change.

Symmetry Keeps Fermions Pure in a Noisy World

A theoretical study reveals how to control and drive a quantum system without causing its decoherence.

Quantumness is famously fragile. Decoherence, particle loss, and other dissipative processes typically destroy delicate quantum superpositions, causing open quantum systems to behave classically. This universal, inevitable fate suggests that, even when a system’s constituents are fully quantum, its nonequilibrium critical points could be described by classical universality classes. That is, the system could belong to a group whose behavior near a critical point is identical and scale invariant regardless of microscopic details. In a new theoretical study, Rohan Mittal and his collaborators at the University of Cologne in Germany have overturned this expectation for open systems of fermions [1]. They identified a particular symmetry, which, if present, blocks most of the noise channels that would ordinarily wash out quantum behavior at large scales.

Pairs of atoms observed existing in two places at once for the first time

Quantum physicists at ANU have observed atoms entangled in motion. “It’s really weird for us to think that this is how the universe works,” says Dr. Sean Hodgman from the ANU Research School of Physics. “You can read about it in a textbook, but it’s really weird to think that a particle can be in two places at once.”

Their experiment using helium atoms represents a major advancement over similar experiments using photons, which are particles of light. Unlike photons, helium atoms have mass and experience gravity. The research is published in Nature Communications.

“Experimentally, it’s extremely hard to demonstrate this,” says lead author and Ph.D. researcher, Yogesh Sridhar. “Several people have tried in the past to show these effects, and they have always come short.”

Silicon quantum computer performs logical operations for the first time

Silicon is ubiquitous in modern electronics, and now it is becoming increasingly useful in quantum computing. In particular, silicon’s compatibility with existing chip technology and its long coherence times in silicon-based spin qubits make it a promising material for scalable quantum computing. A new study, published in Nature Nanotechnology, has demonstrated silicon’s use in a logical quantum processor, representing the first of its kind.

Quantum computers are highly sensitive to errors from environmental noise, creating hurdles for practical quantum computation. To help suppress these errors, information can be encoded in logical qubits using fault-tolerant quantum computation (FTQC). Prior to this study, silicon had not been used for logical operations in FTQC.

“In silicon-based quantum processors, frequency crowding and cross-talk further exacerbate the errors as the system scales. To address these errors, logical encoding stands as the only viable solution by redundantly storing quantum information across multiple physical qubits. While logical qubits and operations have been successfully demonstrated in platforms such as superconducting circuits, neutral atoms, nitrogen-vacancy centers and trapped ions, their implementation in silicon-based spin qubits poses notable technical challenges,” the study authors write.

Earth formed from material exclusively from the inner solar system, planetary scientists show

Planetary scientists have long debated where the material that formed Earth comes from. Despite its location in the inner solar system, they consider it likely that 6–40% of this material must have come from the outer solar system, i.e., beyond Jupiter. For a long time, material from the outer solar system was considered necessary to bring volatile components such as water to Earth. Accordingly, there must also have been an exchange of material between the outer and inner solar systems during the formation of Earth. But is that really true?

Planetary scientists Paolo Sossi and Dan Bower, from ETH Zurich, compared existing data on the isotopic ratios of a wide range of meteorites, including those from Mars and the asteroid Vesta, with those of Earth. Isotopes are sibling atoms of the same element (same number of protons) that have a different mass (different number of neutrons).

The researchers analyzed this data in a new way and arrived at a surprising conclusion: the material that makes up Earth originates entirely from the inner region of the solar system.

Quadratic gravity theory reshapes quantum view of Big Bang

Waterloo scientists have developed a new way to understand how the universe began, and it could change what we know about the Big Bang and the earliest moments of cosmic history. Their work suggests that the universe’s rapid early expansion could have arisen naturally from a deeper, more complete theory of quantum gravity. The paper, “Ultraviolet completion of the Big Bang in quadratic gravity,” appears in Physical Review Letters.

Dr. Niayesh Afshordi, professor of physics and astronomy at the University of Waterloo and Perimeter Institute (PI), led the research team that explored a novel method of combining gravity with quantum physics, the rules that govern how the smallest particles in the universe behave. While general relativity has been successful for more than a century, it breaks down at the extreme conditions that existed at the birth of the universe. To address this problem, the team used Quadratic Quantum Gravity, which remains mathematically consistent even at extremely high energies—similar to the kind present during the Big Bang.

Most existing explanations for the Big Bang rely on Einstein’s theory of gravity, plus additional components added by hand. This new approach offers a more unified picture that connects the earliest moments of the universe to the well-tested cosmology scientists observe today.

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