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Hubble detects first-ever spin reversal of tiny comet

Astronomers using NASA’s Hubble Space Telescope have found evidence that the spinning of a small comet slowed and then reversed its direction of rotation, offering a dramatic example of how volatile activity can affect the spin and physical evolution of small bodies in the solar system. This is the first time researchers have observed evidence of a comet reversing its spin.

The object, comet 41P/Tuttle-Giacobini-Kresák, or 41P for short, likely originated in the Kuiper Belt, and was flung into its current trajectory by Jupiter’s gravity, now visiting the inner solar system every 5.4 years.

After its 2017 close passage around the sun, scientists found that comet 41P experienced a dramatic slowdown in its rotation. Data from NASA’s Neil Gehrels Swift Observatory in May 2017 showed the object was spinning three times more slowly than it had in March 2017 when it was observed by the Discovery Channel Telescope at Lowell Observatory in Arizona.

Quantum experiment shows events may have no fixed order

For the first time, a team of physicists in Austria has carried out an experiment that appears to verify the principle of indefinite causal order: an idea that suggests that timelines of events can exist in multiple orders at the same time. Led by Carla Richter at the Vienna Center for Quantum Science and Technology, the researchers hope their result could finally allow physicists to verify a key prediction of quantum theory. The results have been published in PRX Quantum.

The basic principle of cause and effect underpins everything that happens in the classical world: for an event to occur, it must be triggered by another event in its past. Yet in the quantum world, physicists have long suspected that these rules may not always apply.

Just as quantum particles can exist in superpositions of multiple states which collapse to a single outcome when measured, indefinite causal order suggests something similar may apply to entire sequences of events. Until a measurement is made, multiple orders of cause and effect can exist in superposition.

Tiny LED design could power next-generation technology

From 3D movie screens to augmented-reality devices, many modern technologies rely on our ability to manipulate light. Doing so in a cost-effective and efficient way, however, is often a formidable task. In an article published in Optics Letters, researchers from the University of Osaka announced a new light-emitting diode (LED) design that may help shrink complex optical systems into much smaller devices. The LED produces circularly polarized light using a built-in nanostructured surface, eliminating the need for bulky external optical components.

Circularly polarized light, whose electric field rotates like a corkscrew as it travels, is essential for technologies such as 3D displays, advanced imaging systems, and quantum communication tools. Traditionally, generating this kind of light requires optical components such as polarizers and special plates that modify the light’s phase. However, these components make devices larger, more complex, and harder to integrate.

“Our goal is to simplify the way circularly polarized light is produced,” says corresponding author Shuhei Ichikawa. “By integrating polarization control directly into the LED with a specially designed metasurface, we remove the need for additional optical components.”

Experimental evidence shows how photons spread across multiple paths in an interferometer

The nature of quantum particles has long puzzled scientists. While single-particle interference suggests that a photon can behave like a spread-out wave, a whole photon is only ever detected in one specific place. Traditional interpretations of quantum mechanics often address this by suggesting the particle is in a superposition of being here and there at the same time. However, this tells us only where the particle is when it is measured, not where the particle physically is when no detector is present.

A research team led by Hiroshima University, led by Holger F. Hofmann, professor at the Graduate School of Advanced Science and Engineering, has now developed a method to measure this delocalization without disturbing the photon’s wave-like path.

In a study published in the New Journal of Physics, the researchers applied a modification of the well-established method of “weak measurements” to a two-path interferometer. As the photon traveled, they applied a tiny rotation by a positive angle in one path and a negative angle in the other. If the two paths interfere in the output, the average rotation angle is always zero. However, this is only a statistical average.

New synthetic origin of replication lets multiple plasmids coexist in one bacterial cell

“If it ain’t broke, don’t fix it,” goes the old adage, which Rice University professor James Chappell completely ignored in a recent Nature Communications publication. In the study, Chappell describes an innovation in plasmids, circular pieces of DNA that have been a workhorse of molecular biology research since the 1970s.

“For decades, we’ve been designing experiments around two major limitations of plasmids: fixed copy numbers and incompatibility,” said Chappell, the corresponding author on the study. “While functional, such workarounds are clunky. We created a synthetic version of a part of the plasmid called the origin of replication that allows us to modify the plasmid instead of modifying the experiment.”

Plasmids are typically put into bacterial cells, where they use the cell’s machinery to build proteins and create copies of themselves. Each plasmid generates tiny pieces of a stop signal, called a negative regulator, which binds to the origin of replication (ORI).

Quantum computer accurately simulates real magnetic materials, reproducing national laboratory data

Studying and designing novel materials is a central application of quantum mechanics. Chemists, materials scientists, and physicists focus on subtle interactions in quantum materials and to uncover them they rely on sophisticated computational and experimental techniques. Computer simulations that connect microscopic quantum interactions to measurable material properties complement experimental data to connect structure to function—but classical computers can struggle to simulate those properties. Fortunately, scientists today have a new tool in their toolbox: quantum computers.

In new preprint, a team of researchers from Oak Ridge National Lab’s (ORNL’s) Quantum Science Center (QSC), Purdue University, Los Alamos Laboratory, the University of Illinois at Urbana-Champaign, the University of Tennessee, and IBM used quantum simulation to compute the energy-momentum spectrum of a well-studied magnetic material, KCuF3, showing strong agreement with the spectra measured via neutron scattering. The research is published on the arXiv preprint server.

The quantum simulations employed the IBM Quantum Heron processor, while the experimental data was acquired from neutron sources at the Spallation Neutron Source (SNS) at ORNL and at the Rutherford Appleton Laboratory in the United Kingdom. This work serves as another realization of Richard Feynman’s vision: the use of a well-controlled, programmable quantum system to simulate the properties of a quantum system of interest.

Unlocking scalable entanglement will enable next-generation quantum computing

Quantum computing promises to transform our world in rapid, radical and revolutionary ways: solving in seconds problems that would take classical computers years, accelerating the discovery of new medicines, creating sustainable materials, optimizing complex systems, and strengthening cybersecurity. It does so using qubits, the quantum counterparts of classical bits, which can occupy multiple states simultaneously and enable a fundamentally new kind of computation.

For example, imagine 1,000 trucks need to arrive at 10,000 different locations, each, in different parts of the country. A traditional computation model would examine each of the 10 million possible routes one by one to evaluate their efficacy, but a quantum model would be able to evaluate all those millions of different routes instantaneously.

At the same time, quantum sensing is opening new frontiers in precision measurement, enabling technologies such as ultra-sensitive medical imaging and navigation systems that can detect minute changes in gravity or magnetic fields, capabilities that could allow doctors to identify diseases earlier or help vehicles navigate without GPS. UCF researchers believe the science of light, photonics, may hold the key to unlocking quantum computing’s true potential.

‘Near-misses’ in particle accelerators can illuminate new physics, study finds

Particle accelerators reveal the heart of nuclear matter by smashing together atoms at close to the speed of light. The high-energy collisions produce a shower of subatomic fragments that scientists can then study to reconstruct the core building blocks of matter.

An MIT-led team has now used the world’s most powerful particle accelerator to discover new properties of matter, through particles’ “near-misses.” The approach has turned the particle accelerator into a new kind of microscope—and led to the discovery of new behavior in the forces that hold matter together.

In a study appearing this week in the journal Physical Review Letters, the team reports results from the Large Hadron Collider (LHC)—a massive underground, ring-shaped accelerator in Geneva, Switzerland. Rather than focus on the accelerator’s particle collisions, the MIT team searched for instances when particles barely glanced by each other.

DNA shape explains crucial gene-therapy challenges

CRISPR is a powerful DNA-editing tool that has underpinned huge advancements in human health care in the last decade. It is a precision tool, but is not perfect, and misplaced DNA edits can compromise safety and efficacy, costing billions each year. Researchers at the MRC Laboratory of Medical Sciences (LMS), Imperial College London and the University of Sheffield have published research in Nature showing that the physical twisting of DNA plays an important role in these mistakes. Using a newly developed platform of tiny (nanometer-sized) DNA circles, called DNA minicircles, the team captured never-before-seen interactions between CRISPR and DNA, providing insights that could help eradicate errors altogether.

CRISPR-Cas9 has transformed biology by giving scientists a programmable way to cut and edit DNA. Its ever-growing impact includes groundbreaking therapies for genetic diseases such as sickle cell anemia and an increasing role in personalized cancer treatment and rapid diagnostics. But even carefully designed CRISPR systems can sometimes cut DNA sequences that were not the intended targets.

“It’s a tool that is not perfect and can introduce errors and make edits where it shouldn’t make them,” says Professor David Rueda, head of the Single Molecule Imaging group at the LMS and Chair in Molecular and Cellular Biophysics at Imperial College London. “And it’s an important problem for the industry. It’s been estimated to be $0.3 to $0.9 billions per year in industry costs, in profiling off-targets, redesigning guides and delays.”

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