Department of Applied Physics and Materials Science - Applied Physics

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Highlights

A Pathway to Longer-Lasting Lithium Batteries

08-06-20

The energy density of batteries have been a major challenge for consumer electronics, electric vehicles, and renewable energy sources. Professor Julia R. Greer has made a discovery that could lead to lithium-ion batteries that are both safer and more powerful. Findings provide guidance for how lithium-ion batteries, one of the most common kinds of rechargeable batteries, can safely hold up to 50 percent more energy. "Every power-requiring application would benefit from batteries with lithium instead of graphite anodes because they can power so much more," says Greer. "Lithium is lightweight, it doesn't occupy much space, and it's tremendously energy dense." [Caltech story]

Tags: APhMS research highlights MCE Julia Greer

Superconducting Twisted Bilayer Graphene—Magic not Needed?

07-16-20

A new study shows that superconductivity in twisted bilayer graphene can exist away from the magic angle when coupled to a two-dimensional semiconductor. "Our observations were quite unexpected. It implies that we only scratched the surface of graphene twistronics. These are exciting times for the field," says Stevan Nadj-Perge, Assistant Professor of Applied Physics and Materials Science. [Caltech story]

Tags: APhMS research highlights Stevan Nadj-Perge

Optical Microcomb Device May Result in Improved Telecommunications, Sensors, Clocks

06-19-20

Modern telecommunications often makes use of multiple lasers of different colors to transmit data, but a new device the size of a cigarette pack can replace them. A team of researchers from Caltech, UC Santa Barbara, and the Swiss Federal Institute of Technology Lausanne (EPFL) have developed a new device that will lead to improved optical data transmission and could have applications ranging from communications to the miniaturization of time standards or to the search for exoplanets. Their device converts laser light of a single frequency into an evenly spaced set of many distinct frequencies (a comb of frequencies). The resulting optical frequency microcomb is built from a single piece of silicon, in much the same way as computer chips. And its many colors can replace many separate lasers for data transmission. "The new approach makes the process as easy as switching on a room light," says co-author Kerry Vahala, Ted and Ginger Jenkins Professor of Information Science and Technology and Applied Physics and executive officer for Applied Physics and Materials Science. [Caltech story]

Tags: APhMS research highlights Kerry Vahala

New Superconducting Film Resists a Magnet's Power to Thwart It

04-02-20

To Professor Joseph Falson, electrons are like exotic supercars and his lab wants to build the racetrack. In Falson's analogy, he likens that to driving the supercar down a cobblestone street that limits its speed. "Our job is not to make the supercar, it's just to make the highway," he says. The problem for those who seek to study superconductivity and eventually make practical use of it is that, so far, it has been realized only at ultracold temperatures no warmer than -70 degrees Celsius. "There is a very strong push to realize room-temperature superconductivity—it is one of the holy grails of science," Falson says, "because then you are going to employ these materials in motors or transmission lines, and the loss would be significantly less. It would revolutionize society." [Caltech story]

Tags: APhMS research highlights Joseph Falson

Tiny Optical Cavity Could Make Quantum Networks Possible

03-31-20

Professor Andrei Faraon and team have shown that atoms in optical cavities—tiny boxes for light—could be foundational to the creation of a quantum internet. They identified a rare-earth ytterbium ion in the center of a beam. The ytterbium ions are able to store information in their spin for 30 milliseconds. In this time, light could transmit information to travel across the continental United States. "It's a rare-earth ion that absorbs and emits photons in exactly the way we'd need to create a quantum network," says Faraon. "This could form the backbone technology for the quantum internet." [Caltech story]

Tags: APhMS EE research highlights Andrei Faraon Andrei Ruskuc Jake Rochman John Bartholomew Yan Qi Huan

New Chip-Based Laser Gyroscope Measures Earth's Rotation

03-05-20

Optical gyroscopes are used in applications such as aircraft navigation systems, while MEMS gyroscopes are found in devices like smart phones. Professor Kerry J. Vahala has developed an optical gyroscope that combines some of the best characteristics of each into one device. "For more than 20 years, researchers have speculated about placing optical gyroscopes onto a chip very much like the highly successful MEMS gyroscopes. But until recently, there have been very few compelling experiments," Vahala says. [Caltech story]

Tags: APhMS research highlights Kerry Vahala IST

Microstructures Self-Assemble into New Materials

03-03-20

A new process developed at Caltech makes it possible for the first time to manufacture large quantities of materials whose structure is designed at a nanometer scale—the size of DNA's double helix. Pioneered by Professor Julia R. Greer, "nanoarchitected materials" exhibit unusual, often surprising properties—for example, exceptionally lightweight ceramics that spring back to their original shape, like a sponge, after being compressed. Now, a team of engineers at Caltech and ETH Zurich have developed a material that is designed at the nanoscale but assembles itself—with no need for the precision laser assembly. "We couldn't 3-D print this much nanoarchitected material even in a month; instead we're able to grow it in a matter of hours," says Carlos M. Portela, Postdoctoral Scholar. "It is exciting to see our computationally designed optimal nanoscale architectures being realized experimentally in the lab," says Dennis M. Kochmann, Visiting Associate. [Caltech story]

Tags: APhMS research highlights GALCIT MCE Julia Greer Dennis Kochmann postdocs Carlos Portela

Researchers Develop New Quantum Algorithm

12-19-19

Austin Minnich, Professor of Mechanical Engineering and Applied Physics, Fernando Brandão, Bren Professor of Theoretical Physics, and Garnet Chan, Bren Professor of Chemistry, have developed an algorithm for quantum computers that will help them find use in simulations in the physical sciences. The new algorithm allows a user to find the lowest energy of a given molecule or material. Many people are interested in how to simulate the ground states of molecules and materials. "If we want to do a simulation of water, we could look at how water behaves after it has been blasted into a plasma—an electrically charged gas—but that's not the state water is usually found in; it is not the ground state of water. Ground states are of special interest in understanding the world under ordinary conditions," says Chan. [Caltech story]

Tags: research highlights Austin Minnich Fernando Brandão Garnet Chan

How Electrons Break the Speed Limit

12-10-19

Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, and Jinjian Zhou, Postdoctoral Scholar, have developed a way to predict how electrons interacting strongly with atomic motions will flow through a complex material. "Using a new method, we have been able to predict both the formation and the dynamics of polarons in strontium titanate. This advance is crucial since many semiconductors and oxides of interest for future electronics and energy applications exhibit polaron effects," says Bernardi. [Caltech story]

Tags: APhMS research highlights Marco Bernardi postdocs Jinjian Zhou

Caltech Announces the Schmidt Academy for Software Engineering

10-10-19

Caltech has launched the Schmidt Academy for Software Engineering to train the next generation of science-savvy software engineers and set new standards in scientific software. "This is a recognition that computing, software, and machine learning are going to play a very big role in science. Because Caltech is small and collaborative, we have the opportunity to really make a push in that direction," says Kaushik Bhattacharya, the Howell N. Tyson, Sr., Professor of Mechanics and Materials Science and vice provost. [Caltech release]

Tags: APhMS EE research highlights MCE CMS Tapio Schneider Donnie Pinkston Kaushik Bhattacharya