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Topological solitons power a chip-scale frequency comb source

Caltech scientists have developed a new way to produce optical frequency combs—important tools in devices that keep time and measure distances very precisely—at the chip scale, an advance that should make it easier to incorporate such combs in optical devices and more practical to use them outside the laboratory.

To generate the combs, the new research demonstrates the utility of a robust class of light pulses, called topological solitons, that had been previously predicted but largely unexplored until now. The scientists, led by Caltech’s Alireza Marandi, professor of electrical engineering and applied physics, describe their findings in a paper published in Nature.

Frequency combs are light sources that emit a precise ruler-like “comb” of many evenly spaced frequencies. Over the last three decades, they have become important tools in spectroscopy, in telecommunications, and even in astronomical research. Currently, most frequency comb sources rely on bulky tabletop laser sources. The new work shows that an electrically pumped laser diode integrated with a photonic chip with strong nonlinearity can serve as a frequency comb source.

Protein modification discovery opens cancer therapy possibilities

A research team led by Purdue University’s W. Andy Tao has discovered a new type of protein modification related to cellular mutation that impairs a crucial enzyme’s ability to help drive energy processes. Their discovery, published in Nature Chemistry, opens a new route to therapeutic cancer intervention.

“Mutation is considered the driving mechanism leading to cancer. Many mutations are hidden and harmless, but the mutation of enzymes like kinases can lead to the uncontrolled growth of cancer cells,” said Tao, a professor of biochemistry in Purdue’s College of Agriculture.

The study wades into the interactive dynamic complexity of the human genome (containing 20,000 to 25,000 genes) and the human proteome (containing more than 1 million proteins). The researchers identified a new modification on proteins because of the mutation in the isocitrate dehydrogenase (IDH) enzyme, which affects how kinase enzymes control protein function.

XRISM clocks hot wind of galaxy M82 at 2 million mph

For the first time, astronomers have directly measured the speed of superheated gas billowing from a cauldron of stellar activity at the heart of M82, a nearby galaxy undergoing an extraordinary burst of star formation. The material is moving more than 2 million miles (over 3 million kilometers) per hour and appears to be the primary force driving a cooler, well-studied, galaxy-scale wind.

Researchers made the calculations using data from the Resolve instrument aboard the XRISM (X-ray Imaging and Spectroscopy Mission) spacecraft.

“The classic model of starburst galaxies like M82 suggests that shock waves from star formation and supernovae near the center heat gas, kick-starting a powerful wind,” said Erin Boettcher, an astrophysicist at the University of Maryland, College Park and NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Making quantum vibrations nonlinear to enable phonon-phonon interactions

Phonons are the quantum units of mechanical vibration. They describe how motion propagates through a solid at the smallest possible scales, in much the same way that electrons describe electric currents. Because phonons can be exceptionally stable and sensitive, they are used in quantum science and technology.

Researchers can already detect and control individual phonons. The problem lies in making phonons interact with each other in a predictable and tunable way, which would be a key requirement for building complex quantum systems like quantum computers.

Interactions are essential in quantum technologies. Whether the goal is sensing tiny forces or processing information, one quantum excitation must be able to influence another. In practice, this requires nonlinearity, which means that adding one excitation changes how the system responds to the next, rather than each excitation behaving independently.

Finding order in disorder: New mechanism amplifies transverse electron transport

For decades, it has been widely believed that electrons move most efficiently in materials that are clean and highly ordered. Much like water flowing more easily through a smooth pipe, conventional wisdom has held that electrical transport improves as a material’s internal structure becomes more perfectly arranged. However, a recent study shows that the opposite can also be true. A research team at POSTECH in South Korea has discovered that engineered disorder can actually enhance electron transport.

The work was conducted by Prof. Hyungyu Jin of the Department of Mechanical Engineering at POSTECH (Pohang University of Science and Technology), Dr. Sang Jun Park (currently a postdoctoral researcher at the National Institute for Materials Science, NIMS, Japan), Prof. Hyun-Woo Lee of the Department of Physics at POSTECH, and Ph.D. student Hojun Lee.

Their findings are published in Physical Review Letters.

Now you see it, now you don’t: Material can transition between quantum states

A team of scientists led by the U.S. Department of Energy’s (DOE) Argonne National Laboratory has identified a rare, switchable quantum property in a new type of nickel sulfide material. The discovery could have applications in high-speed transistors, adaptive sensors and other devices that require a material’s electronic structure to be controlled on the fly. The research is published in the journal Matter.

The compound, KxNi4S2 (0 ≤ x ≤ 1), contains nickel and sulfur sandwiched between layers of potassium. The “(0 ≤ x ≤ 1)” in the name means that the amount of potassium in the material can vary from no potassium at all to a full potassium atom, depending on the sample.

First detailed in a 2021 paper, it was created as part of an ongoing quest to develop more superconductors. As researchers examined the layered material’s characteristics, they happened upon a remarkable feature: applying an electrical current could drive the potassium layers out, collapsing the sandwich and changing the material’s structure.

Dancing to invisible choreography, quantum computers can balance the noise

Large-scale quantum computers are waiting in the wings. One of the main reasons we don’t have them yet is because quantum hardware is so noisy. This isn’t the type of noise you’d want to shush in a crowded theater. When it comes to computers, noise means errors that crop up when conditions aren’t perfect.

“We need to find a way to detect errors and correct for them,” said graduate student Evangelos Piliouras. Working with physicist Ed Barnes, Piliouras devised a method to reduce the noise and make quantum computers more noise tolerant. His work was published in npj Quantum Information.

Noise can have real-world implications even in a traditional computer, which uses a stream of electrical signals called bits that represent the 1s and 0s that make up binary code. Noise can knock a 0 into a 1, and a credit card transaction, for instance, might fail.

Astronomers Detect Strange “Chirp” From a Supernova, Revealing Hidden Physics

Astronomers studying a distant superluminous supernova uncovered a strange pattern hidden in its light: a rapidly accelerating “chirp.” For decades, astronomers have used distant supernova explosions as cosmic beacons to study fundamental physics and measure properties of the universe. While exam

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