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Physicists made atoms behave like a quantum circuit

Using ultracold atoms and laser light, researchers recreated the behavior of a Josephson junction—an essential component of quantum computers and voltage standards. The appearance of Shapiro steps in this atomic system reveals a deep universality in quantum physics and makes elusive microscopic effects visible for the first time.

Josephson junctions play a central role in modern physics and technology. They enable extremely precise measurements, define the international standard for electrical voltage, and serve as essential components inside many quantum computers. Despite their importance, the quantum-scale processes occurring inside superconductors are notoriously difficult to observe directly.

To overcome this challenge, researchers at the RPTU University of Kaiserslautern-Landau turned to quantum simulation. Instead of studying electrons inside a solid material, they recreated the Josephson effect using ultracold atoms. Their approach involved separating two Bose-Einstein condensates (BECs) with an exceptionally thin optical barrier created by a focused laser beam that was moved in a controlled, periodic way. Even in this atomic system, the defining signatures of Josephson junctions emerged. The experiment revealed Shapiro steps, which are distinct voltage plateaus that appear at multiples of a driving frequency, just as they do in superconducting devices. Published in the journal Science, the work stands as a clear example of how quantum simulation can uncover hidden physics.

Entanglement enhances the speed of quantum simulations, transforming long-standing obstacles into a powerful advantage

Researchers from the Faculty of Engineering at The University of Hong Kong (HKU) have made a significant discovery regarding quantum entanglement. This phenomenon, which has long been viewed as a significant obstacle in classical quantum simulations, actually enhances the speed of quantum simulations. The findings are published in Nature Physics in an article titled “Entanglement accelerates quantum simulation.”

Simulating the dynamic evolution of matter is fundamental to understanding the universe, yet it remains one of the most challenging tasks in physics and chemistry. For decades, “entanglement”—the complex correlation between quantum particles—has been viewed as a formidable barrier. In classical computing, high entanglement makes simulations exponentially harder to perform, often acting as a bottleneck for studying complex quantum systems.

Led by Professor Qi Zhao from the School of Computing and Data Science at HKU, the research team collaborated with Professor You Zhou from Fudan University and Professor Andrew M. Childs from the University of Maryland, and overturned this long-held belief. They discovered that while entanglement hinders classical computers, it actually accelerates quantum simulations, turning a former obstacle into a powerful resource.

North Pacific winter storm tracks shifting poleward much faster than predicted

Alaska’s glaciers are melting at an accelerating pace, losing roughly 60 billion tons of ice each year. About 4,000 kilometers to the south, in California and Nevada, records for heat and dryness are being shattered, creating favorable conditions for wildfire events.

One major factor contributing to climate change in both regions is the northward shift of winter storm tracks across the North Pacific Ocean. These storms transport heat and moisture from Earth’s warmer regions toward the pole; when their tracks shift northward, more heat and moisture reach Alaska, while natural ventilation of the southwestern United States is reduced, driving temperatures upward.

In a new study published in Nature, Dr. Rei Chemke of the Weizmann Institute of Science’s Earth and Planetary Sciences Department and Dr. Janni Yuval of Google Research show that the storms’ northward shift is occurring much faster than climate models have predicted. Moreover, using a new metric based on sea-level pressure—a parameter measured consistently for decades—the researchers found that this shift is not part of natural climate variability but rather a clear consequence of climate change.

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