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Category: computing – Page 183

Understanding quantum computing’s most troubling problem—the barren plateau

For the past six years, Los Alamos National Laboratory has led the world in trying to understand one of the most frustrating barriers that faces variational quantum computing: the barren plateau.

“Imagine a landscape of peaks and valleys,” said Marco Cerezo, the Los Alamos team’s lead scientist. “When optimizing a variational, or parameterized, , one needs to tune a series of knobs that control the solution quality and move you in the landscape. Here, a peak represents a bad solution and a valley represents a good solution. But when researchers develop algorithms, they sometimes find their model has stalled and can neither climb nor descend. It’s stuck in this space we call a barren .”

For these quantum computing methods, barren plateaus can be mathematical dead ends, preventing their implementation in large-scale realistic problems. Scientists have spent a lot of time and resources developing quantum algorithms only to find that they sometimes inexplicably stall. Understanding when and why barren plateaus arise has been a problem that has taken the community years to solve.

Harnessing magnons for quantum information processing

Researchers have determined how to use magnons—collective vibrations of the magnetic spins of atoms—for next-generation information technologies, including quantum technologies with magnetic systems.

From the computer hard drives that store our data to the motors and engines that drive power plants, magnetism is central to many transformative technologies. Magnetic materials are expected to play an even larger role in new technologies on the horizon: the transmission and processing of quantum information and the development of quantum computers.

New research led by scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory developed an approach to control the collective magnetic properties of atoms in real time and potentially deploy them for next-generation information technologies. This discovery could aid in developing future quantum computers, which can perform tasks that would be impossible using today’s computers, as well as “on chip” technologies—with magnetic systems embedded on semiconductor chips, or “on chip.”

New proposal aims to protect patients with high-risk brain implants

As companies such as Elon Musk’s Neuralink begin human trials of high-risk brain implants, a new proposal calls for a major change in how the U.S. handles injuries caused by the devices.

The article published in Science suggests a “no-fault” compensation program to help harmed by devices like (BCIs)—even when no one is legally at fault.

These devices, which are implanted in the brain to treat serious conditions like epilepsy or paralysis, can offer life-changing benefits. But they also come with serious risks such as seizures, strokes or even death. And when something goes wrong, patients often have no way to get help or compensation.

No, Quantum Mechanics does Not Need Complex Numbers

No journal is perfect, and despite Nature being considered a high quality journal, I have recently come across a paper which is, to put it bluntly, is slop. It is a bit of slop easily debunkable by anyone who can do a tiny bit of linear algebra.

The paper is titled “Quantum theory based on real numbers can be experimentally falsified.” The entire paper is misleading because it presents a very specific representation of quantum mechanics based solely on real numbers, shows that it leads to different predictions than traditional quantum theory, and then concludes therefore complex numbers are a necessity for complex theory.

This is obviously false. A complex number is just two real numbers stitched together. Classical computers can’t operate on complex numbers and so they just break them apart into two real floating point numbers and do the equivalent calculations in that form, but then display it as a complex number, and they can reproduce anything you can reproduce using complex numbers. Indeed, my quantum computer simulator I had put together myself uses its own complex matrix library for linear algebra, and each element of the matrix is specified by two real numbers.

Animation technique simulates the motion of squishy objects

The technique simulates elastic objects for animation and other applications, with improved reliability compared to other methods. In comparison, many existing simulation techniques can produce elastic animations that become erratic or sluggish or can even break down entirely.

To achieve this improvement, the MIT researchers uncovered a hidden mathematical structure in equations that capture how elastic materials deform on a computer. By leveraging this property, known as convexity, they designed a method that consistently produces accurate, physically faithful simulations.

Oxford physicists recreate extreme quantum vacuum effects

Physicists at the University of Oxford have successfully simulated how light interacts with empty space – a phenomenon once thought to belong purely to the realm of science fiction. The simulations recreated a bizarre phenomenon predicted by quantum physics, where light appears to be generated from darkness. The findings pave the way for real-world laser facilities to experimentally confirm bizarre quantum phenomena. The results have been published in Communications Physics.

Using advanced computational modelling, a research team led by the University of Oxford, working in partnership with the Instituto Superior Técnico in the University of Lisbon, has achieved the first-ever real-time, three-dimensional simulations of how intense laser beams alter the ‘quantum vacuum’ – a state once assumed to be empty, but which quantum physics predicts is full of virtual electron-positron pairs.

Excitingly, these simulations recreate a bizarre phenomenon predicted by quantum physics, known as vacuum four-wave mixing. This states that the combined electromagnetic field of three focused laser pulses can polarise the virtual electron-positron pairs of a vacuum, causing photons to bounce off each other like billiard balls – generating a fourth laser beam in a ‘light from darkness’ process. These events could act as a probe of new physics at extremely high intensities.

New study visualizes platinum doping on ultrathin 2D material with atomic precision

A popular 2D active material, molybdenum disulfide (MoS2), just got a platinum upgrade at an atomic level. A study led by researchers from the University of Vienna and Vienna University of Technology embedded individual platinum (Pt) atoms onto an ultrathin MoS2 monolayer and, for the first time, pinpointed their exact positions within the lattice with atomic precision.

The study, published in the journal Nano Letters, achieved this feat with an innovative approach that integrates targeted defect creation in the MoS2 monolayer, controlled platinum deposition, and a high-contrast computational microscopic imaging technique—ptychography.

The researchers believe that this new strategy for ultra-precise doping and mapping offers new pathways for understanding and engineering atomic-scale features in 2D systems.

Predicting chemical storm fronts: Framework enables predictive control over patterned polymer formation

Imagine being tasked with baking a soufflé, except the only instruction provided is an ingredient list without any measurements or temperatures.

It would likely take an enormous amount of time, effort and ingredients to bake the perfect soufflé. It would require trial and error—tweaking ingredient measurements, altering the temperature and baking duration—but what if you had a model that could predict the final product before anything ever went into the mixing bowl? It would not only save weeks’ worth of time and resources but could also provide useful details like why and how the soufflé rose and collapsed when it did or why the texture didn’t turn out how you expected.

Researchers at the Beckman Institute for Advanced Science and Technology aren’t quite baking soufflés. Instead, they developed a that digs into the chemical “recipe” of polymer manufacturing to provide predictive control over how materials self-organize to give rise to new textures and properties.

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