Department of Applied Physics and Materials Science - Materials Science

News & Events

Highlights

Caltech Awarded Federal Funding for Quantum Research

09-25-18

EAS Professors were among a small group of Caltech scientists and engineering who have won federal grants for research in quantum computing, and quantum networks. Professor Nadj-Perge (lead PI) along with co-PIs Professors Marco Bernardi and Andrei Faraon as well as co-investigator Professor Julia Greer have received funding for the program ”Quantum States in Layered Heterostructures Controlled by Electrostatic Fields and Strain," which is administered within the U.S. Department of Energy's Basic Energy Sciences division. Professor Austin Minnich is a co-PI of the program, "Quantum simulation of materials and molecules using quantum computation," which is part of the National Science Foundation's Research Advanced by Interdisciplinary Science and Engineering (RAISE)-Transformational Advances in Quantum Systems (TAQS) effort. [Caltech story]

Tags: APhMS research highlights MCE Julia Greer Austin Minnich Andrei Faraon Marco Bernardi Stevan Nadj-Perge

President Rosenbaum Highlights Postdocs as "Unsung Heroes"

09-24-18

In a letter to the Caltech community during National Postdoc Appreciation Week, the Caltech President emphasizes the role this key group plays at the Institute. He stated, “Caltech's mission of world-leading research and education depends crucially on our postdoctoral scholars. Although their time at Caltech may be short, they quickly become vital parts of the Institute's intellectual fabric.” [President’s Letter] [EAS Postdoc Resource Page]

Tags: APhMS EE GALCIT MedE MCE CMS ESE Thomas Rosenbaum postdocs

Clues to Solar Cell Efficiency Found at Atomic Level

06-20-18

Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, has teamed up with physics colleague Professor David Hsieh, to offers new insight into a promising solar cell material called perovskites. "Despite being a relatively new technology, perovskite solar cells are now almost as efficient as solar cell materials that have been around for decades. But we still don't know why perovskite solar cells work so well," says Professor Bernardi, [Caltech story]

Tags: APhMS research highlights Marco Bernardi David Hsieh

Exact Optical Frequencies on Demand

06-11-18

Professor Kerry J. Vahala and colleagues have developed a prototype of a miniature device that synthesizes frequencies on demand with about 1 Hertz accuracy. It combines a frequency comb developed at the National Institute of Standards and Technology (NIST) with a "fine-toothed" frequency comb developed at Caltech. To create the finely spaced comb teeth, the Caltech resonator must be about 100 times larger than the NIST device. Its larger size can potentially make this comb very power hungry. "Too much power in a small space can damage any electronics to which the resonator is connected," Professor Vahala says. "Also, in the future, these synthesizer devices could operate on battery power in smartphone-sized devices where they cannot draw much power." But the Caltech comb can generate specific frequencies with minimal amounts of power. [Caltech story]

Tags: APhMS research highlights Kerry Vahala

Building the Starshot Sail

06-04-18

Professor Harry A. Atwater, Jr. is an advisor to a multi-disciplinary $100-million project aimed at designing a spacecraft that can be launched to planets surrounding other stars and reach them within our lifetime. The Breakthrough Starshot Program has three big technical challenges: The first is to build the so-called photon engine, the laser that's capable of propelling the sail; the second is to design the sail itself; and the third is to design the payload, which will be a tiny spacecraft capable of taking images and spectral data and then beaming them back to the earth. Professor Atwater’s role is to help the program define pathways to making a viable lightsail that's compatible with the other objectives of the whole program. [Caltech story]

Tags: APhMS research highlights Harry Atwater

Quantum and non-linear forces yield peculiar thermal expansion in silicon

05-16-18

Most materials expand when heated. At temperatures below room temperature, silicon shows the opposite behavior, shrinking as it is heated. Even at room temperature the normal thermal expansion of silicon is rather small. A team led by Professor Brent Fultz wanted to know why, and found that the unusual property is the result of quantum effects coupled by the nonlinear forces between atoms in silicon. [Read the paper]

Tags: APhMS research highlights Brent Fultz Dennis Kim

Solving Pieces of the Genetic Puzzle

05-09-18

Postdoctoral scholar Nathan Belliveau working in the laboratory of Professor Rob Phillips has applied a method called Sort-Seq to mutate small pieces of noncoding regions in E. coli and determined which regions contain binding sites. Binding sites are the locations where specialized proteins that are involved in transcription—the first step in the process of gene expression—attach to DNA. "Humans have such a wide variety of cells—muscle cells, neurons, photoreceptors, blood cells, to name a few," says Professor Phillips. "They all have the same DNA, so how do they each turn out so differently? The answer lies in the fact that genes can be regulated—turned on or off, dialed up and dialed down—differently in different tissues. Until now, there have been no general principles to help us understand how this regulation was encoded." [Caltech story]

Tags: research highlights Rob Phillips APh postdocs Nathan Belliveau

New Process Allows 3-D Printing of Nanoscale Metal Structures

02-09-18

Professor Julia Greer and graduate student Andrey Vyatskikh have created complex nanoscale metal structures using 3-D printing. The process, once scaled up, could be used in a wide variety of applications and opens the door to the creation of a new class of materials with unusual properties that are based on their internal structure. [Caltech story]

Tags: research highlights MedE MCE Julia Greer MatSci Andrey Vyatskikh

The Microscopic Origin of Efficiency Droop in LEDs

11-20-17

Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, and his colleagues’ semiconductor research has shown that the coupling between electrons and thermal vibrations may be sapping energy from Light-emitting diodes—or LEDs. "Our work shows for the first time that the ever-present interaction between electrons with lattice vibrations can, by itself, explain why excited electrons can leak out of the active layer and account for inefficiencies in GaN LEDs," Professor Bernardi says. [Caltech story]

Tags: APhMS research highlights Marco Bernardi

Studying Entropy in Metallic Glasses

10-10-17

Brent Fultz, Barbara and Stanley R. Rawn, Jr., Professor of Materials Science and Applied Physics, and colleagues have pinpointed that arrangement of atoms is the main source of an increase in entropy during the glass transition. One persistent mystery about metallic glasses occurs at the so-called "glass transition." A cold metallic glass is hard and brittle, but when it is heated past a certain point—the glass transition—it becomes soft. [Caltech story]

Tags: APhMS research highlights Brent Fultz MatSci