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Category: computing – Page 56

Integrative quantum chemistry method unlocks secrets of advanced materials

A new computational approach developed at the University of Chicago promises to shed light on some of the world’s most puzzling materials—from high-temperature superconductors to solar cell semiconductors—by uniting two long-divided scientific perspectives.

“For decades, chemists and physicists have used very different lenses to look at materials. What we’ve done now is create a rigorous way to bring those perspectives together,” said senior author Laura Gagliardi, Richard and Kathy Leventhal Professor in the Department of Chemistry and the Pritzker School of Molecular Engineering. “This gives us a new toolkit to understand and eventually design materials with extraordinary properties.”

When it comes to solids, physicists usually think in terms of broad, repeating band structures, while chemists focus on the local behavior of electrons in specific molecules or fragments. But many important materials—such as organic semiconductors, metal–organic frameworks, and strongly correlated oxides—don’t fit neatly into either picture. In these materials, electrons are often thought of as hopping between repeating fragments rather than being distributed across the material.

Scientists Discover How To “Purify” Light, Paving the Way for Faster, More Secure Quantum Technology

University of Iowa scientists have identified a new way to “purify” photons, a development that could improve both the efficiency and security of optical quantum technologies.

The team focused on two persistent problems that stand in the way of producing a reliable stream of single photons, which are essential for photonic quantum computers and secure communication systems. The first issue, known as laser scatter, arises when a laser is aimed at an atom to trigger the release of a photon, the basic unit of light. Although this method successfully generates photons, it can also produce extra, unwanted ones. These additional photons reduce the efficiency of the optical system, similar to how stray electrical currents interfere with electronic circuits.

A second complication comes from the way atoms occasionally respond to laser light. In uncommon cases, an atom releases more than one photon at the same time. When this happens, the precision of the optical circuit suffers because the extra photons disrupt the intended orderly flow of single photons.

Caltech Team Sets Record with 6,100-Qubit Array

Quantum computers will need large numbers of qubits to tackle challenging problems in physics, chemistry, and beyond. Unlike classical bits, qubits can exist in two states at once—a phenomenon called superposition. This quirk of quantum physics gives quantum computers the potential to perform certain complex calculations better than their classical counterparts, but it also means the qubits are fragile. To compensate, researchers are building quantum computers with extra, redundant qubits to correct any errors. That is why robust quantum computers will require hundreds of thousands of qubits.

Now, in a step toward this vision, Caltech physicists have created the largest qubit array ever assembled: 6,100 neutral-atom qubits trapped in a grid by lasers. Previous arrays of this kind contained only hundreds of qubits.

This milestone comes amid a rapidly growing race to scale up quantum computers. There are several approaches in development, including those based on superconducting circuits, trapped ions, and neutral atoms, as used in the new study.

The neutral-atom platform shows promise for scaling up quantum computers.

How Bose-Einstein condensates replicate Shapiro steps

The microscopic processes taking place in superconductors are difficult to observe directly. Researchers at the RPTU University of Kaiserslautern-Landau have therefore implemented a quantum simulation of the Josephson effect: They separated two Bose-Einstein condensates (BECs) by means of an extremely thin optical barrier.

The characteristic Shapiro steps were observed in the atomic system. The research was published in the journal Science.

Two superconductors separated by a wafer-thin insulating layer—that’s how simple a Josephson junction looks. But despite its simple structure, it harbors a quantum mechanical effect that is now one of the most important tools of modern technology: Josephson contacts form the heart of many quantum computers and enable high-precision measurements—such as the measurement of very weak magnetic fields.

Pinpointing the glow of a single atom to advance quantum emitter engineering

Researchers have discovered how to design and place single-photon sources at the atomic scale inside ultrathin 2D materials, lighting the path for future quantum innovations.

Like perfectly controlled light switches, quantum emitters can turn on the flow of single particles of light, called photons, one at a time. These tiny switches—the “bits” of many quantum technologies—are created by atomic-scale defects in materials.

Their ability to produce light with such precision makes them essential for the future of quantum technologies, including quantum computing, secure communication and ultraprecise sensing. But finding and controlling these atomic light switches has been a major scientific challenge—until now.

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