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Engineers achieve efficient integration of quantum dot lasers on silicon chiplets

Lasers that are fabricated directly onto silicon photonic chips offer several advantages over external laser sources, such as greater scalability. Furthermore, photonic chips with these “monolithically” integrated lasers can be commercially viable if they can be manufactured in standard semiconductor foundries.

III-V semiconductor lasers can be monolithically integrated with photonic chips by directly growing a crystalline layer of material, such as indium arsenide, on silicon substrate. However, photonic chips with such integrated laser source are challenging to manufacture due to mismatch between structures or properties of III-V semiconductor material and silicon. “Coupling loss” or the loss of optical power during transfer from laser source to silicon waveguides in the photonic chip is yet another concern when manufacturing with monolithically integrated lasers.

In a study that was recently published in the Journal of Lightwave Technology, Dr. Rosalyn Koscica from the University of California, United States, and her team successfully integrated quantum dot (QD) lasers monolithically on silicon photonics chiplets.

Spin currents control device magnetization using low-cost materials

Research from the University of Minnesota Twin Cities gives new insight into a material that could make computer memory faster and more energy-efficient.

The study was recently published in Advanced Materials, a peer-reviewed scientific journal. The researchers also have a patent on the technology.

As technology continues to grow, so does the demand for emerging memory technology. Researchers are looking for alternatives and complements to existing memory solutions that can perform at high levels with low energy consumption to increase the functionality of everyday technology.

A common food additive solves a sticky neuroscience problem

An interdisciplinary team working on balls of human neurons called organoids wanted to scale up their efforts and take on important new questions. The solution was all around them.

For close to a decade now, the Stanford Brain Organogenesis Program has spearheaded a revolutionary approach to studying the brain: Rather than probe intact brain tissues in humans and other animals, they grow three-dimensional brain-like tissues in the lab from , creating models called human neural organoids and assembloids.

Beginning in 2018 as a Big Ideas in Neuroscience project of Stanford’s Wu Tsai Neurosciences Institute, the program has brought together neuroscientists, chemists, engineers, and others to tackle the neural circuits involved in pain, genes that drive neurodevelopmental disorders, new ways to study brain circuits, and more.

‘Standard candle’ particle measurement enables hunt for hybrid mesons

A rather unassuming particle is playing an important role in the hunt for subatomic oddities. Similar to protons and neutrons, mesons are composed of quarks bound together by the strong nuclear force. But these short-lived particles have different characteristics that can reveal new information about the atomic nucleus and how the universe works.

Advancing this understanding could one day enable new discoveries in many fields, ranging from nuclear power to medicine and materials engineering.

The so-called a2 meson is a relatively lightweight system of quarks. It is produced in experiments at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility.

First physics results from the sPHENIX particle detector

The sPHENIX particle detector, the newest experiment at the Relativistic Heavy Ion Collider (RHIC) at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, has released its first physics results: precision measurements of the number and energy density of thousands of particles streaming from collisions of near-light-speed gold ions.

As described in two papers recently accepted for publication in Physical Review C and the Journal of High Energy Physics, these measurements lay the foundation for the ’s detailed exploration of the quark–gluon plasma (QGP), a unique state of matter that existed just microseconds after the Big Bang some 14 billion years ago. Both studies are available on the arXiv preprint server.

The new measurements reveal that the more head-on the nuclear smashups are, the more charged particles they produce and the more total energy those firework-like sprays of particles carry. That matches nicely with results from other detectors that have tracked QGP-generating collisions at RHIC since 2000, confirming that the new detector is performing as promised.

OLEDs light the way to faster longer-distance wireless communication

In the race to develop faster and more flexible wireless communication technologies, researchers are turning to an unexpected source: the same organic light-emitting diodes (OLEDs) found in smartphone screens and TVs.

A recent study by scientists at the University of St Andrews and the University of Cambridge, published in Advanced Photonics, shows that OLEDs can be engineered to transmit data at record-breaking speeds over surprisingly long distances—potentially transforming how we connect devices in the future.

The paper is titled “High-speed based on dinaphthylperylene achieving 4-Gbps communication.”

World’s First Hybrid Chip Combines Electronics, Photonics, and Quantum Power

An interdisciplinary academic team has successfully integrated quantum light sources and control electronics onto a single silicon chip. In a significant advancement for quantum technology, researchers from Boston University, UC Berkeley, and Northwestern University have developed the first chip

Different Bacterial Genes Have Different Turn-Ons

Not all genes respond in the same way to regulation by the same molecule—a property that might enable cells to produce complex genetic responses.

Genes in living cells may become active or may be suppressed in response to environmental stimuli such as heat or the availability of nutrients. For bacteria, this gene regulation often appears to be a simple “on-off switch” controlled by regulatory proteins called transcription factors (TFs). But researchers have now found that different genes might respond differently to the same stimulus even if they are regulated by the same TF [1]. The team activated genes involved in DNA repair and observed gene-to-gene variations in their protein production patterns. Such differences might have been exploited by evolution to achieve complex responses with relatively few molecular components, the researchers suggest.

In the typical scenario, a TF binds to a region of a so-called promoter, a DNA sequence next to a gene. If the TF is the type that blocks gene expression, it prevents the enzyme RNA polymerase from binding and thus from beginning the process of producing the protein that the gene encodes. Because of thermal fluctuations (noise), the TF may spontaneously unbind, allowing gene expression to proceed until it rebinds. The rate of TF binding depends on its concentration, so fluctuations in concentration will cause changes in gene expression.

Unusual Plasma Waves Above Jupiter’s North Pole

A spacecraft observes a new oscillation mode in the low-density plasma.

The Juno space probe has spent the past nine years observing Jupiter and its moons. As the spacecraft’s mission draws to a close, the precession of its orbit has caused its closest approach to the gas giant to shift toward the north pole, enabling it to uncover a surprise: an unusual pattern of plasma waves in the planet’s magnetosphere. Now Robert Lysak of the University of Minnesota and his colleagues describe these waves and propose a mechanism for generating them [1]. Their theory offers a new component to include in planetary magnetosphere models and opens a new plasma regime to further exploration.

According to textbook plasma physics, collective waves of electrons in a plasma called Langmuir waves tend to oscillate parallel to magnetic-field lines at a so-called plasma frequency that’s much greater than the ions’ angular frequency around these field lines, their gyrofrequency. Meanwhile, ions tend to oscillate perpendicular to magnetic-field lines as Alfvén waves, with an upper frequency limit corresponding to the ion gyrofrequency. The waves detected by Juno, however, departed from that paradigm: The Alfven waves’ frequency extended only to the plasma frequency, which was less than the ion gyrofrequency. And the waves’ frequency never exceeded the plasma frequency.