Department of Applied Physics and Materials Science - Materials Science

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Highlights

Computational Tool for Materials Physics Growing in Popularity

04-05-21

Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, has developed a new piece of software that makes it easier to study the behavior of electrons in materials—even materials that have been predicted but do not yet exist. The software, called Perturbo, is gaining traction among researchers. "Over the next decade, we will continue to expand the capabilities of our code, and make it the go-to for first-principles calculations of electron dynamics," Bernardi says. [Caltech story]

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New Insight into Nonlinear Optical Resonators Unlocks Door to Numerous Potential Applications

02-25-21

Devices known as optical parametric oscillators are among the widely used nonlinear resonators in optics; they are "nonlinear" in that there is light flowing into the system and light leaking out, but not at the same wavelengths. Though these oscillators are useful in a variety of applications, including in quantum optics experiments, the physics that underpins how their output wavelength, or spectrum, behaves is not well understood. "When you add strong nonlinearity to resonators, you enter what we call a 'rich physics regime,'" says Alireza Marandi, Assistant Professor of Electrical Engineering and Applied Physics. "'Rich' in physics terms usually means complicated and hard to use, but we need nonlinearities to create useful functionalities such as switching for computing." To be able to make full use of nonlinear optical resonators, researchers want to be able to understand and model the physics that underpin how they work. Marandi and his colleagues recently uncovered a potential way to engineer those rich physics, while discovering phase transitions in the light that is generated by the resonators. [Caltech story]

Tags: APhMS EE research highlights KNI Alireza Marandi

Caltech and NTT Research Launch Collaboration to Develop World’s Fastest Coherent Ising Machine

01-25-21

Researchers from Caltech and NTT Research are collaborating to develop a high-speed Coherent Ising Machine (CIM). A CIM is a network of optical parametric oscillators (OPOs) programmed to solve problems that have been mapped to an Ising model, which is a mathematical abstraction of magnetic systems composed of competitively interacting spins, or angular momentums of fundamental particles. The principal investigator at Caltech for this four-and-a-half-year joint project is Kerry Vahala, Ted and Ginger Jenkins Professor of Information Science and Technology and Applied Physics; Executive Officer for Applied Physics and Materials Science. “We are delighted at the prospect of working with Professor Vahala to develop an extremely small and high-speed CIM,” said NTT Research PHI Lab Director, Yoshihisa Yamamoto. “This work will advance our understanding of the CIM’s capabilities, map well with ongoing and related work with other institutions, provide new demonstrations of this awesomely powerful new information system and, we hope, set standards for the CIM’s speed and size.” [NTT Research story] [Business Wire story]

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Tiny Shape-Shifting Polymers Developed for Potential Medical Applications

01-04-21

Julia Greer, Ruben F. and Donna Mettler Professor of Materials Science, Mechanics and Medical Engineering; Fletcher Jones Foundation Director of the Kavli Nanoscience Institute, has developed a process for generating three-dimensional architected polymers with heat-dependent "shape memory" properties: that is, when heated, the material folds and unfolds itself into a new preordained shape. These shape memory polymers could one day be used to perform complex tasks inside the human body, such as unclogging a blocked artery or pulling out a blood clot. [Caltech story]

Tags: APhMS research highlights MedE Julia Greer KNI Luizetta Elliott

Titanium Atom That Exists in Two Places at Once in Crystal to Blame for Unusual Phenomenon

12-07-20

Crystals are usually good at conducting heat. By definition, their atomic structure is highly organized, which allows atomic vibrations—heat—to flow through them as a wave. Austin Minnich, Professor of Mechanical Engineering and Applied Physics, has discovered why a perfect crystal is not good at conducting heat, although it seemingly should be. "We have found that quantum mechanical effects can play a huge role in setting the thermal transport properties of materials even under familiar conditions like room temperature," says Austin Minnich. [Caltech story]

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A Method to Map Brain Circuits in Real Time

10-16-20

A new approach called integrated neurophotonics could allow researchers to track the activity of all the neurons that make up a particular brain circuit. To deepen their understanding of the brain, neuroscientists must be able to map in great detail the neural circuits that are responsible for tasks such as processing sensory information or forming new memories. Now, a new approach may allow for the activity of all of the thousands to millions of neurons within a particular brain circuit to be observed in real time. Dense recording at depth—that is the key," says Michael Roukes, Frank J. Roshek Professor of Physics, Applied Physics, and Bioengineering. [Caltech story]

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New Device Powers Wearable Sensors Through Human Motion

10-16-20

Wei Gao, Assistant Professor of Medical Engineering, has been developing sensors as well as novel approaches to power them. Previously, he created a sensor that could monitor health indicators in human sweat that is powered by sweat itself. Now, Gao has developed a new way to power wireless wearable sensors: He harvests kinetic energy that is produced by a person as they move around. "Instead of using fancy materials, we use commercially available flexible circuit boards," he says. "This material is cheap and very durable and mechanically robust over long periods of time." [Caltech story]

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Professor Gao Unveils Sensor that Rapidly Detects COVID-19 Infection Status, Severity, and Immunity

10-02-20

One feature of the COVID-19 virus that makes it so difficult to contain is that it can be easily spread to others by a person who has yet to show any signs of infection. Wei Gao, Assistant Professor of Medical Engineering, has developed a new type of multiplexed test (a test that combines multiple kinds of data) with a low-cost sensor that may enable the at-home diagnosis of a COVID infection through rapid analysis of small volumes of saliva or blood, without the involvement of a medical professional, in less than 10 minutes. "This is the only telemedicine platform I've seen that can give information about the infection in three types of data with a single sensor," Gao says. "In as little as a few minutes, we can simultaneously check these levels, so we get a full picture about the infection, including early infection, immunity, and severity." [Caltech story]

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Effective Pathway to Convert Greenhouse Gas into Valuable Products

09-18-20

A research team from Caltech and the UCLA Samueli School of Engineering has demonstrated a promising way to efficiently convert carbon dioxide into ethylene—an important chemical used to produce plastics, solvents, cosmetics, and other important products globally. They developed nanoscale copper wires with specially shaped surfaces to catalyze a chemical reaction that reduces greenhouse gas emissions while simultaneously generating ethylene. "The idea of using copper to catalyze this reaction has been around for a long time, but the key is to accelerate the rate so it is fast enough for industrial production," says William A. Goddard III, Charles and Mary Ferkel Professor of Chemistry, Materials Science, and Applied Physics. [Caltech story]

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Advancing Future Quantum Science Efforts

08-27-20

Five new Department of Energy centers will apply quantum information science to emerging technologies. The centers will develop cutting-edge quantum technologies for use in a wide range of possible applications including scientific computing; fundamental physics and chemistry research; and the design of solar cells and of new materials and pharmaceuticals. Caltech faculty will participate in four of the new science centers: the Quantum Systems Accelerator, led by the Lawrence Berkeley National Laboratory, also known as Berkeley Lab; the Quantum Science Center, led by Oak Ridge National Laboratory; Q-NEXT, led by Argonne National Laboratory; and the Co-design Center for Quantum Advantage, led by Brookhaven National Laboratory. [Caltech story]

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