Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: computing

Quantum Error Correction Faces Another Hurdle

Newly identified correlated errors in superconducting qubits could limit the performance of error-correction schemes needed for a practical quantum computer.

Building a working quantum computer is challenging because its basic components, qubits, are highly sensitive to environmental disturbances that compromise computation. Whereas classical bits can only undergo bit-flip errors that change 0 to 1 or vice versa, qubits also suffer from so-called phase errors that degrade the fundamental quantum interference effects essential for quantum computation. Joining several good, but not perfect, physical qubits into a logical qubit makes quantum error correction possible (see Research News: Cracking the Challenge of Quantum Error Correction). But that strategy can fail if too many qubits become faulty at the same time. In one leading hardware platform, superconducting circuits, such correlated qubit errors are typically triggered every few tens of seconds when ionizing radiation from the environment deposits energy into the chip hosting the circuits.

Mathematical framework solves asteroid route planning exactly for first time

A new publication from Bielefeld University sets a benchmark in optimization research. Together with an international team, Professor Michael Römer from the Faculty of Business Administration and Economics has developed a mathematical framework that solves a complex problem from space logistics exactly for the first time: the optimal planning of a route to visit several asteroids under conditions that are as close to reality as possible. The study is published in the INFORMS Journal on Computing.

At the center of the research is the so-called Asteroid Routing Problem. It addresses the question: In what order should a spacecraft visit multiple asteroids if both travel time and fuel consumption are to be minimized? The challenge is that, unlike in classical routing problems, the travel time between destinations is constantly changing because all celestial bodies are in continuous motion.

The idea for the study originated in Bielefeld, sparked by a success in a competition organized by the European Space Agency (ESA). During a research stay in Bielefeld, lead author Isaac Rudich revisited the topic and, together with the team, developed a new solution approach.

Magnon lifetime extended 100x paves the way for mini quantum computers

Magnons are tiny waves in magnetization that travel through solid magnetic materials, much like the ripples that spread across a pond when a stone is thrown into it. Unlike photons, which travel through empty space or optical fibers, magnons propagate within a magnetic solid. Their wavelengths can be reduced to the nanometer range, meaning that magnonic circuits could, in principle, fit onto a chip no larger than those found in today’s smartphones. Furthermore, as an excitation of a solid, a magnon naturally couples to numerous other fundamental quasi-particles—phonons, photons and others—making it an ideal building block for hybrid quantum systems and quantum metrology.

Until now, there has been one major obstacle: magnons have had a very short lifetime. This lifetime—the period during which they can reliably carry quantum information—was limited to a few hundred nanoseconds at best. Far too short for any practical quantum computation. The team led by Wiener has now achieved a breakthrough: the physicists were able to measure magnon lifetimes of up to 18 microseconds—almost a hundred times longer than any value observed to date.

In this state, magnons are no longer fleeting signals, but become long-lived, reliable carriers of quantum information, comparable to the superconducting qubits used in today’s leading quantum processors. The study has recently been published in the journal Science Advances.

Ultrafast MRI uncovers brain signal direction: New scan may help decode autism, Alzheimer’s and hallucinations

Researchers at the Champalimaud Foundation in Lisbon have for the first time managed to identify with an imaging technique whether nervous impulses in the brain of rats are flowing in a “bottom-up” (feedforward), carrying information about visual input, or a “top-down” (feedback) direction, carrying information about expectations or predictions on a given task or about the perception of the world around us. Their results, published in Nature Communications, could have important implications for understanding changes in the brains of people with hallucinations, Alzheimer’s, schizophrenia, autism, and other conditions.

Joana Carvalho, first author of the new study, who at the time was working in the Preclinical MRI lab led by senior author Noam Shemesh (she has since become a group leader at Coimbra University), “came up with the ideas, did the experiments and analyzed the results. I just brought the MRI expertise,” says Shemesh good-humoredly. Co-author Koen V. Haak from Tilburg University (Netherlands) gave assistance with the computational models and the others helped with the experiments.

The team showed that spontaneous feedforward and feedback nervous impulses in these rodents (the brain never sleeps) each have a unique, distinct signature, which can be detected by using a method they developed, called uFLARE (UltraFast Layer-Resolved Encoding), a neuroimaging technique designed to map brain activity with unprecedented high temporal and spatial resolutions.

In Silico Analysis of the Chikungunya Virus and SARS-CoV-2 Macrodomain

The chikungunya virus (ChikV) was first isolated during an arthritic disease outbreak in Tanzania in 1952 [1, 2]. ChikV is a mosquito-borne virus that belongs to the Alphavirus genus of the Togaviridae family. ChikV infections have emerged as a global health risk with approximately 16.9 million cases per year [3]. Major symptoms of ChikV infection include severe fever, rashes, and joint pain. Chronic arthritis-like symptoms may persist and can be debilitating [4, 5]. ChikV, a positive-sense RNA virus, encodes 5 structural proteins and 4 nonstructural proteins (NSP1 to NSP4) [6]. Nonstructural protein 3 (NSP3) consists of a conserved macrodomain (Mac1) at the N-terminus, a poorly conserved hypervariable domain, and a central zinc-binding domain known as the alphavirus unique domain [7]. The macrodomain fold is highly conserved across evolution, having been identified in bacteria, algae, and eukaryotes [8, 9]. It has been suggested that ChikV Mac1 suppresses the host immune response through its adenosine diphosphate ribosyl (ADP-ribosyl) hydrolase activity [10], which removes ADP-ribose posttranslational modifications from target host proteins by hydrolyzing mono-ADP-ribosylated aspartate and glutamate residues. Mac1 has therefore emerged as a promising antiviral drug target [10], supported by evidence suggesting that it is a key determinant of ChikV virulence in mice. Despite their therapeutic potential, efforts to identify ChikV inhibitors have had limited success. A fragment screen of ~14,000 compounds identified only weak inhibitors (e.g., 2-pyrimidone-4-carboxylic acid scaffold, with one of the compounds showing IC50 of 23 μM) [11]. Another computational docking and simulation study screened 820 compounds and predicted that natural compounds from plants, including apigetrin, baicalin, baloxavir, luteoloside, rutaecarpine, and amentoflavone [12], are Mac1 inhibitors. The predicted binding affinity of baicalin was −10.8 kcal/mol against ChikV Mac1. Another study identified N-[2-(5-methoxy-1 H-indol-3-yl) ethyl]-2-oxo-1,2-dihydroquinoline-4-carboxamide through virtual screening of 245,532 natural compounds, followed by in vitro validation using a microscale thermophoresis binding assay (binding constant [Kd] of 1.066 × 10−6 ± 0.95 μM) and in vivo inhibition of ChikV replication [13].

Similar to ChikV, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) NSP3 contains 3 tandem macrodomains, with Mac1 serving as the catalytically active macrodomain that binds and hydrolyzes mono-ADP-ribose on posttranslationally modified target host proteins [14,15]. SARS-CoV-2 Mac1 is essential for viral pathogenesis and represents a promising drug target [16,17]. In contrast to ChikV Mac1, it has proven amenable to inhibitor development. An early crystallographic screen of approximately 2,600 compounds revealed 234 fragment structures bound to SARS-CoV-2 Mac1 [18]. Using these hits, several optimized inhibitors were designed, followed by another round of crystallographic screening [19]. Among the resulting top inhibitors was AVI-4206, a potent inhibitor with an IC50 of 20 nM that is effective in an animal model of SARS-CoV-2 infection [20]. Other studies have identified additional promising scaffolds, including 2-amide-3-methylester thiophene scaffold derivatives that bind SARS-CoV-2 Mac1 (IC50 = 1.5 μM) and inhibit viral replication [21], synthetic analogs of ADP-ribose that bind SARS-CoV-2 Mac1 with nanomolar affinity [22], and pyrrolo-pyrimidine-based compounds that inhibit viral replication in SARS-CoV-2 [23].

The structural similarity between ChikV Mac1 and SARS-CoV-2 Mac1 [24] has not translated into similar druggability. One strategy to improve ligand-binding affinity is to exploit the presence of water molecules in the binding site by designing inhibitors that effectively use them to form bridging interactions that strengthen binding to the protein [25]. This strategy is particularly relevant for Mac1 ADP-ribose-binding sites, which are large, solvent exposed, and known to maintain an extensive network of ordered water molecules upon ADP binding. In SARS-CoV-2 Mac1, ADP-ribose forms several water-mediated interactions, resulting in the water network in the ADP-ribose-binding site reorganizing upon ligand binding [18,26].

Oldest Moon Craters Are Best Targets for Water Ice

“We found that the earlier a region became shadowed, the larger the area that was able to accumulate ice,” said Dr. Oded Aharonson. [ https://www.labroots.com/trending/space/30512/moon-craters-targets-water-ice-2](https://www.labroots.com/trending/space/30512/moon-craters-targets-water-ice-2)

What are the best places on the Moon to find water ice that can be used for future crewed missions to the Moon’s surface? This is what a recent study published in Nature Astronomy hopes to address as a team of scientists investigated potential regions of the Moon where future astronauts could have the highest chance of finding water ice. This study has the potential to help scientists, engineers, mission planners, and future astronauts narrow the scope for finding the best locations of water ice on the Moon to aid in future crewed missions, thus negating the need for water supplies from Earth.

For the study, the researchers analyze data obtained from the Lyman-Alpha Mapping Project (LAMP), which is an instrument on the Lunar Reconnaissance Orbiter designed to map the entire surface of the Moon in far ultraviolet light. They combined these findings with computer models designed to simulate how and when water was delivered to the Moon millions to billions of years ago.

In the end, the researchers found that Shackleton Crater, a portion of which is located directly at the lunar south pole, is not the most ideal location for water ice, which has long been thought. In contrast, the researchers propose that Haworth Crater is the ideal location for finding water ice. Additionally, the researchers found that some of these regions have been building water ice for as long as 1.5 billion years.

Hidden 3D atomic structure of relaxor ferroelectrics revealed for first time

Materials called relaxor ferroelectrics have been used for decades in technologies like ultrasounds, microphones, and sonar systems. Their unique properties come from their atomic structure, but that structure has stubbornly eluded direct measurement.

Now a team of researchers from MIT and elsewhere has directly characterized the three-dimensional atomic structure of a relaxor ferroelectric for the first time. The findings, reported in Science, provide a framework for refining models used to design next-generation computing, energy, and sensing devices.

“Now that we have a better understanding of exactly what’s going on, we can better predict and engineer the properties we want materials to achieve,” says corresponding author James LeBeau, MIT’s Kyocera Professor of Materials Science and Engineering.

New sensor sniffs out pneumonia on a patient’s breath

Diagnosing some diseases could be as easy as breathing into a tube. MIT engineers have developed a test to detect disease-related compounds in a patient’s breath. The new test could provide a faster way to diagnose pneumonia and other lung conditions. Rather than sit for a chest X-ray or wait hours for a lab result, a patient may one day take a breath test and get a diagnosis within minutes.

The new breath test is a portable, chip-scale sensor that traps and detects synthetic compounds, or “biomarkers,” of disease, which are initially attached to inhalable nanoparticles. The biomarkers serve as tiny tags that can only be unlocked and detached from the nanoparticle by a very particular key, such as a disease-related enzyme.

The idea is that a person would first breathe in the nanoparticles, similar to inhaling asthma medicine. If the person is healthy, the nanoparticles would eventually circulate out of the body intact. If a disease such as pneumonia is present, however, enzymes produced as a result of the infection would snip off the nanoparticles’ biomarkers. These untethered biomarkers would be exhaled and measured, confirming the presence of the disease.

/* */