Using Applied Physics to Explain How Accretion Disks Drive Astrophysical Jets
04-01-16
Paul M. Bellan, Professor of Applied Physics, has developed a new model explaining why astrophysical jets always originate from stars having accretion disks, the progenitors of planets. The relationship between jets and accretion disks has eluded scientists for many years and what happens to the angular momentum of accreting particles has also long been a mystery. Professor Bellan’s model explains how the disks power the jets as well as how angular momentum is removed from accreting material in the disks. The model involves peculiar inward spiraling trajectories of clumps of charged and neutral particles, and shows that the disk and jets together form an electric circuit where the disk is the battery and the jet is the load. [Read the Paper]
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Paul Bellan
Seeking a Balanced Equation
03-21-16
Applied Physics graduate student Peter Hung, working with Professor Roukes, is one of the Caltech students featured in a recent E&S article. “In our lab, we shoot molecules of different sizes and shapes at really small mechanical resonators—tiny bridges almost 1,000 times smaller than the width of your hair—and use the change in the resonant frequency (how fast these bridges are vibrating) to reconstruct the shape and mass of the molecules that we’re shooting,” Hung explains. [E&S article]
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Michael Roukes
Peter Hung
Novel Calibration Tool Will Help Astronomers
01-27-16
Kerry Vahala, Ted and Ginger Jenkins Professor of Information Science and Technology and Applied Physics; Executive Officer for Applied Physics and Materials Science, and colleagues have developed a novel calibration tool, called a laser frequency comb, which could allow astronomers to take a major step in discovering and characterizing earthlike planets around other stars. The comb produces easily resolvable lines, without any need for filtering and is built from off-the-shelf components developed by the telecommunications industry. "We have demonstrated an alternative approach that is simple, reliable, and relatively inexpensive," says Professor Vahala. [Caltech story]
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Kerry Vahala
Inaugural Centers Announced for the Materials Genome Initiative
10-05-15
William A. Goddard III, Charles and Mary Ferkel Professor of Chemistry, Materials Science, and Applied Physics, will be the Caltech Principle Investigator for one of U.S. Department of Energy’s inaugural centers for the Materials Genome Initiative (MGI). The initiative was launched by the White House to “help businesses discover, develop, and deploy new materials twice as fast.” The three inaugural centers are receiving $8 million to “integrate theory and computation with experiment and provide the materials community with advanced tools and techniques in support of the MGI.” Professor Goddard and colleagues will be working on the Computational Synthesis of Materials Software Project with the goal of developing the next-generation of methods and software to predict and control materials processes at the level of electrons. [Learn more]
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William Goddard
Atomic Fractals in Metallic Glasses
09-18-15
Julia R. Greer, Professor of Materials Science and Mechanics, and colleagues including graduate student David Chen have shown that metallic glasses has an atomic-level structure although it differs from the periodic lattices that characterize crystalline metals. "Our group has solved this paradox by showing that atoms are only arranged fractally up to a certain scale," Greer says. "Larger than that scale, clusters of atoms are packed randomly and tightly, making a fully dense material, just like a regular metal. So we can have something that is both fractal and fully dense." [Caltech story]
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Julia Greer
David Chen
New, Ultrathin Optical Devices Shape Light in Exotic Ways
09-03-15
Andrei Faraon, Assistant Professor of Applied Physics and Materials Science, and colleagues have created silicon nanopillars devices capable of manipulating light in ways that are very difficult or impossible to achieve with conventional optical components. The devices are precisely arranged into a honeycomb pattern to create a "metasurface" that can control the paths and properties of passing light waves. Professor Faraon describes, "this new technology is very similar to the one used to print semiconductor chips onto silicon wafers, so you could conceivably manufacture millions of systems such as microscopes or cameras at a time." [Caltech story] [BBC video clip]
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Andrei Faraon
Seeing Quantum Motion
08-31-15
Keith Schwab, Professor of Applied Physics, has found a way to observe and control the quantum motion of an object that is large enough to see. Schwab's group has learned how to cool the motion of small micrometer-scale objects to produce the quantum ground state. This quantum motion is theoretically an intrinsic part of the motion of all objects. Schwab and his colleagues designed a device that would allow them to observe this quantum motion and then manipulate it. The ability to control quantum noise could one day be used to improve the precision of very sensitive measurements, such as those designed to search for signs of gravitational waves. [Caltech Story]
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Keith Schwab