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Category: engineering – Page 16

Symmetry plays a crucial role in understanding fundamental phenomena such as conservation laws, the classification of phases of matter, and their transitions. Recently, researchers have been exploring ways to manipulate symmetries in quantum many-body systems with time-dependent driving protocols and, in particular, engineering new symmetries that do not naturally occur. This significantly enriches the toolbox for quantum simulation and computation, and has led to many exciting discoveries of nonequilibrium phases such as discrete time crystals. However, controlling multiple symmetries—especially in a simple and experimentally friendly way—has remained a challenge. In this work, we propose a novel method to engineer hierarchical symmetries by time-dependent protocols.

By carefully controlling how symmetry-indicating observables evolve over time, we show how to create a sequence of symmetries that emerge one after another, each with distinct properties. Our method relies on a recursive construction that hierarchically minimizes the effects of symmetry-breaking processes. This leads to a corresponding sequence of prethermal steady states with controllable lifetimes, each exhibiting a lower symmetry than the preceding one. We illustrate this protocol with several examples, demonstrating how different types of order can emerge through hierarchical symmetry breaking.

This toolbox of hierarchical symmetries opens a new path to stabilizing quantum states and controlling unwanted symmetry-breaking effects, which can be particularly useful in quantum computing and quantum simulation. The construction applies to classical and quantum, fermionic and bosonic, interacting and noninteracting systems. The underlying mechanism generalizes state-of-the-art dynamical decoupling techniques and is implementable on present-day quantum simulation platforms.

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To describe how matter works at infinitesimal scales, researchers designate collective behaviors with single concepts, like calling a group of birds flying in sync a “flock” or “murmuration.” Known as quasiparticles, the phenomena these concepts refer to could be the key to next-generation technologies.

In a recent study published in Science Advances, a team of researchers led by Shengxi Huang, associate professor of electrical and computer engineering and materials science and nanoengineering at Rice, describe how one such type of quasiparticle—polarons—behaves in tellurene, a nanomaterial first synthesized in 2017 that is made up of tiny chains of tellurium atoms and has properties useful in sensing, electronic, optical and .

“Tellurene exhibits dramatic changes in its electronic and optical properties when its thickness is reduced to a few nanometers compared to its bulk form,” said Kunyan Zhang, a Rice doctoral alumna who is a first author on the study. “Specifically, these changes alter how electricity flows and how the material vibrates, which we traced back to the transformation of polarons as tellurene becomes thinner.”

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Enhanced Sensitivity and Wave-Structure Interaction in Nonsingular Flat-Band Lattices with Compact Localized States https://arxiv.org/html/2412.05610v1

A team of UConn College of Engineering (CoE) researchers have achieved a major milestone in the field of phononics with the first experimental demonstration of an all-flat phononic band structure (AFB). Phononics concerns the study of sound and heat control.

The breakthrough, detailed in an article just published in Physical Review Letters, introduces a new class of materials capable of uniquely controlling sound and vibrations by trapping energy with unprecedented intensity, offering exciting possibilities for potential applications in acoustics, vibration insulation, energy harvesting, and beyond.

The work, led by Professor Osama Bilal, director of the Wave Engineering Laboratory for Extreme and Intelligent Matter (We-Xite), along with doctoral student Mahmoud Samak, unlocks a new recipe for engineering materials with exotic behavior. In the experiments, the material serves a double function, Bilal explains, by being a perfect sound vacuum and wave amplifier at the same time.

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Physicists have spent more than a century measuring and making sense of the strange ways that photons, electrons, and other subatomic particles interact at extremely small scales. Engineers have spent decades figuring out how to take advantage of these phenomena to create new technologies.

In one such phenomenon, called , pairs of photons become interconnected in such a way that the state of one instantly changes to match the state of its paired photon, no matter how far apart they are.

Nearly 80 years ago, Albert Einstein referred to this phenomenon as “spooky action at a distance.” Today, entanglement is the subject of research programs across the world—and it’s becoming a favored way to implement the most fundamental form of quantum information, the qubit.

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In a significant step toward creating a sustainable and circular economy, Rice University researchers have published a study in the journal Carbon demonstrating that carbon nanotube (CNT) fibers can be fully recycled without any loss in their structure or properties. This discovery positions CNT fibers as a sustainable alternative to traditional materials like metals, polymers and the much larger carbon fibers, which are notoriously difficult to recycle.

“Recycling has long been a challenge in the materials industry—metals recycling is often inefficient and energy-intensive, polymers tend to lose their properties after reprocessing and carbon fibers cannot be recycled at all, only downcycled by chopping them up into short pieces,” said corresponding author Matteo Pasquali, director of Rice’s Carbon Hub and the A.J. Hartsook Professor of Chemical and Biomolecular Engineering, Materials Science and NanoEngineering and Chemistry.

“As CNT fibers are being scaled up, we asked whether and how these new materials could be recycled in the future so as to proactively avoid waste management problems that emerged as other engineered materials reached large-scale use. We expected that recycling would be difficult and would lead to significant loss of properties. Surprisingly, we found that fibers far exceed the recyclability potential of existing engineered materials, offering a solution to a major environmental issue.”

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A research team from Yokohama National University has developed a novel approach to investigate how the orientation and behavior of electrons in titanium affect its physical properties. Their findings, published in Communications Physics on December 18, 2024, offer valuable insights that could lead to the creation of more advanced and efficient titanium alloys.

Titanium is highly prized for its exceptional resistance to chemical corrosion, lightweight nature, and impressive strength-to-weight ratio. Its biocompatibility makes it an ideal material for medical applications such as implants, prosthetics, and artificial bones, while its strength and durability make it indispensable in aerospace engineering and precision manufacturing.

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Bimetallic particles, made from a combination of a noble metal and a base metal, have unique catalytic properties that make them highly effective for selective heterogeneous hydrogenation reactions. These properties arise from their distinctive geometric and electronic structures. For hydrogenation to be both effective and selective, it requires specific interactions at the molecular level, where the active atoms on the catalyst precisely target the functional group in the substrate for transformation.

Nanoscale Engineering and Electronic Structure Tuning

Scaling these particles down to nanoscale atomic clusters or single-atom alloys further enhances their catalytic performance. This reduction in size increases surface dispersion and optimizes the use of noble metal atoms. Additionally, these nanoscale changes alter the electronic structure of the active sites, which can significantly influence the activity and selectivity of the reaction. By carefully adjusting the bonding between noble metal single atoms and the base metal host, researchers can create flexible environments that fine-tune the electronic properties needed to activate specific functional groups. Despite these advances, achieving atomically precise fabrication of such active sites remains a significant challenge.

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Students from the Toms River School District in New Jersey will have the chance to connect with NASA astronauts Don Pettit and Butch Wilmore as they answer prerecorded science, technology, engineering, and mathematics (STEM) related questions from aboard the International Space Station.

Watch the 20-minute space-to-Earth call in collaboration with Science Friday at 10 a.m. EST on Tuesday, Jan. 14, on NASA+ and learn how to watch NASA content on various platforms, including social media.

Science Friday is a nonprofit dedicated to sharing science with the public through storytelling, educational programs, and connections with audiences. Middle school students will use their knowledge from the educational downlink to address environmental problems in their communities.

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