Conjoined ‘Racetracks’ make new Optical Device possible

Credit: Brian Long

Kerry Vahala and collaborators from UC Santa Barbara have found a unique solution to an optics problem. When we last checked in with Caltech’s Kerry Vahala three years ago, his lab had recently reported the development of a new optical device called a turnkey frequency microcomb that has applications in digital communications, precision time keeping, spectroscopy, and even astronomy.

This device, fabricated on a silicon wafer, takes input laser light of one frequency and converts it into an evenly spaced set of many distinct frequencies that form a train of pulses whose length can be as short as 100 femtoseconds (quadrillionths of a second). (The comb in the name comes from the frequencies being spaced like the teeth of a hair comb.)

Now Vahala (BS ’80, MS ’81,...

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When is an Aurora not an Aurora?

Phenomena called ‘Steve’ and ‘picket fence’ are masquerading as auroras, graduate student argues

nighttime photo of mountain with pinkish swirls and green stripes and stars shining through
The purple and white emissions at the top are referred to as “Steve,” while the green emissions are called “picket fence.” The rare phenomena, which are distinct from the typical aurora, often occur together and may be caused by similar conditions at the edge of space. The photo was taken looking south over Berg Lake toward Mt. Robson in the Canadian Rockies, British Columbia, Canada.
Courtesy of Robert Downie, robertdowniephotography.com

While auroras occur at high latitude, the associated phenomena Steve and the picket fence occur farther south and at lower altitude. Their emissions also differ from aurora...

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Genetic Mutations that Promote Reproduction tend to Shorten Human Lifespan, study shows

Concept illustration of a man and his DNA aging. Image credit: Nicole Smith, made with Midjourney

A University of Michigan-led study based on a review of genetic and health information from more than 276,000 people finds strong support for a decades-old evolutionary theory that sought to explain aging and senescence.

In 1957, evolutionary biologist George Williams proposed that genetic mutations that contribute to aging could be favored by natural selection if they are advantageous early in life in promoting earlier reproduction or the production of more offspring. Williams was an assistant professor at Michigan State University at the time.

Williams’ idea, now known as the antagonistic pleiotropy theory of aging, remains the prevailing evolutionary explanation of senescence, the process of becoming old or aging...

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A Superconducting Junction made from a Single 2D Material promises to Harness Strange New Physics

image of a Josephson junction
Figure 1: A schematic image showing a Josephson junction (central section) made from a single layer of tungsten telluride. The red spheres are electron with spin up, while the blue ones have spin down. © 2023 RIKEN Advanced Device Laboratory

Physicists at RIKEN have developed an electronic device that hosts unusual states of matter, which could one day be useful for quantum computation.

When a material exists as an ultrathin layer—a mere one or a few atoms thick—it has totally different properties from thicker samples of the same material. That’s because confining electrons to a 2D plane gives rise to exotic states...

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