Lifeboat Foundation

In a rare non-magnetic kagome material, a topological metal cools into a superconductor through a sequence of novel charge density waves. Researchers have discovered a complex landscape of electronic states that can co-exist on a kagome lattice, resembling those in high-temperature superconductor.

The Computational Cosmology group of the Department of Astronomy and Astrophysics (DAA) of Valencia University (UV) has published an article in The Astrophysical Journal Letters, one of the international journals with the greatest impact in Astrophysics, which shows, with complex theoretical-computational models, that cosmic voids are constantly replenished with external matter.

Most important, the encoded logical qubit performed better than the physical ones on which it depends, at least in some ways. For example, the researchers succeeded in preparing either the logical 0 or the logical 1 state 99.67% of the time—better than the 99.54% for the individual qubits. “This is really the first time that the quality of the [logical] qubit is better than the components that encode it,” says Monroe, who is cofounder of IonQ, a company developing ion-based quantum computers.

However, Egan notes, the encoded qubit did not outshine the individual ions in every way. Instead, he says, the real advance is in demonstrating fault tolerance, which means the error-correcting machinery works in a way that doesn’t introduce more errors than it corrects. “Fault tolerance is really the design principle that prevents errors from spreading,” says Egan, now at IonQ.

Martinis questions that use of the term, however. To claim true fault-tolerant error correction, he says, researchers must do two other things. They must show that the errors in a logical qubit get exponentially smaller as the number of physical qubits increases. And they must show they can measure the ancillary qubits repeatedly to maintain the logical qubit, he says.

Since the discovery of superconductivity in Sr₂RuO₄ in 1,994 hundreds of studies have been published on this compound, which have suggested that Sr₂RuO₄ is a very special system with unique properties. These properties make Sr₂RuO₄ a material with great potential, for example, for the development of future technologies including superconducting spintronics and quantum electronics by virtue of its ability to carry lossless electrical currents and magnetic information simultaneously. An international research team led by scientists at the University of Konstanz has been now able to answer one of the most interesting open questions on Sr₂RuO₄: why does the superconducting state of this material exhibit some features that are typically found in materials known as ferromagnets, which are considered being antagonists to superconductors? The team has found that Sr₂RuO₄ hosts a new form of magnetism, which can coexist with superconductivity and exists independently of superconductivity as well. The results have been published in the current issue of Nature Communications.

After a research study that lasted several years and involved 26 researchers from nine different universities and research institutions, the missing piece of the puzzle seems to have been found. Alongside the University of Konstanz, the universities of Salerno, Cambridge, Seoul, Kyoto and Bar Ilan as well as the Japan Atomic Energy Agency, the Paul Scherrer Institute and the Centro Nazionale delle Ricerche participated in the study.

For more than 20 years, D-Wave has been synonymous with quantum annealing. Its early bet on this technology allowed it to become the world’s first company to sell quantum computers, but that also somewhat limited the real-world problems its hardware could solve, given that quantum annealing works especially well for optimization problems like protein folding or route planning. But as the company announced at its Qubits conference today, a superconducting gate-model quantum computer — of the kind IBM and others currently offer — is now also on its roadmap.

D-Wave believes the combination of annealing, gate-model quantum computing and classic machines is what its businesses’ users will need to get the most value from this technology. “Like we did when we initially chose to pursue annealing, we’re looking ahead,” the company notes in today’s announcement. “We’re anticipating what our customers need to drive practical business value, and we know error-corrected gate-model quantum systems with practical application value will be required for another important part of the quantum application market: simulating quantum systems. This is an application that’s particularly useful in fields like materials science and pharmaceutical research.”

Scientists have demonstrated new behaviour, vital for the creation of quantum computers, that marks a major breakthrough.

For the first time, researchers were able to show in an experiment that a variety of quantum computing pieces, taken together, were more accurate than the sum of their parts.

Individually, quantum computers are built out of a range of different pieces, some of which can sometimes break. But in the new experiment, scientists showed that those pieces stuck together can be less prone to error than any particular part.

Imagine you sit down and pick up your favourite book. You look at the image on the front cover, run your fingers across the smooth book sleeve, and smell that familiar book smell as you flick through the pages. To you, the book is made up of a range of sensory appearances.

Effective methods for decoupling superconducting qubits (SQs) from parasitic environmental noise sources are critical for increasing their lifetime and phase fidelity. While considerable progress has been made in this area, the microscopic origin of noise remains largely unknown. In this work, first principles density functional theory calculations are employed to identify the microscopic origins of magnetic noise sources in SQs on an α-Al_{2}O_{3} substrate. The results indicate that it is unlikely that the existence of intrinsic point defects and defect complexes in the substrate are responsible for low frequency noise in these systems. Rather, a comprehensive analysis of extrinsic defects shows that surface aluminum ions interacting with ambient molecules will form a bath of magnetic moments that can couple to the SQ paramagnetically. The microscopic origin of this magnetic noise source is discussed and strategies for ameliorating the effects of these magnetic defects are proposed.

PDF | Condensed matter systems act as mini-universes with emergent low-energy properties drastically different from those of the standard model. A case… | Find, read and cite all the research you need on ResearchGate.

Researchers have discovered a complex landscape of electronic states that can co-exist on a kagome lattice, resembling those in high-temperature superconductors, a team of Boston College physicists reports in an advance electronic publication of the journal Nature.

The focus of the study was a bulk single crystal of a topological kagome metal, known as CsV₃Sb₅—a metal that becomes superconducting below 2.5 degrees Kelvin, or minus 455 degrees Fahrenheit. The exotic material is built from atomic planes composed of Vanadium atoms arranged on a so-called kagome lattice—described as a pattern of interlaced triangles and hexagons—stacked on top of one another, with Cesium and Antimony spacer layers between the kagome planes.

The material offers a window into how the physical properties of quantum solids—such as light transmission, electrical conduction, or response to a magnetic field —relate to the underlying geometry of the atomic lattice structure. Because its geometry causes destructive interference and “frustrates” the kinetic motion of traversing electrons, kagome lattice materials are prized for offering the unique and fertile ground for the study of quantum electronic states described as frustrated, correlated and topological.