Interdisciplinary sound-wave study holds promise for new technologies

Siv Schwink
8/17/2016 12:25 PM

An array with a wave traveling through it before and after a modulation which changes the propagation pathway. Image courtesy of Taylor Hughes, University of Illinois at Urbana-Champaign.
An array with a wave traveling through it before and after a modulation which changes the propagation pathway. Image courtesy of Taylor Hughes, University of Illinois at Urbana-Champaign.
Physics professor Taylor Hughes and mechanical science and engineering professor Gaurav Bahl of the University of Illinois at Urbana-Champaign are part of an interdisciplinary team that will study non-reversible sound wave propagation over the next four years, with a range of promising potential applications.

The National Science Foundation has announced a $2-million research award to the team, which includes University of Oregon physics professor Hailin Wang and Duke University electrical and computer engineering professor Steven Cummer. The grant is part of a broader $18-million NSF-funded initiative, the Emerging Frontiers in Research and Innovation (EFRI) program, supporting nine teams—a total of 37 researchers at 17 institutions—to pursue fundamental research in the area of new light and acoustic wave propagation, known as NewLAW.

An NSF news release issued August 16, 2016, emphasizes the great potential of this line of inquiry to transform the ways in which electronic, photonic, and acoustic devices are designed and employed, and to enable completely new functionalities.

"We're really excited about starting this project,” comments Hughes. “We looked at several possible funding opportunities and the NSF's Emerging Frontiers program ended up being the best fit for our ambitious, interdisciplinary focus.

“This is the first program I have worked on that is so tightly connected with engineering, and it is rewarding to know that our work might have a technological impact. We also have some nice plans for outreach efforts that go hand in hand with our research goals."

The specific research being done by the team from U. of I., Duke, and UO has implications for noise reduction, improvements in ultrasound imaging in healthcare, nondestructive sound-based testing of materials, and signal processing for communication systems.

Propagating waves—electromagnetic, light, or sound waves—are used in a very wide range of communication, computation, signal processing, and sensing systems. Devices used in these systems are made of naturally obtained materials which do not allow one-way propagation of waves (especially sound) while blocking the reverse path. The team will develop techniques to fundamentally control the directionality of sound wave propagation in newly engineered materials.

Unidirectional sound-wave propagation will enable building isolators and circulators for signal protection and routing, and for signal shielding and cloaking applications. Manipulating materials to allow waves only one direction of travel represents a significant engineering challenge that extends across physical domains from optics, to electronics, to acoustics.

The research team proposes a new concept for achieving non-reciprocal sound propagation, through spatio-temporal modulation of the material in conjunction with dispersion engineering of modes. The proposed research will experimentally develop the concept in three distinct multiphysical platforms spanning from nano-scale to macro-scale; including the coupling of phonons to electromagnetic and acoustic waves in structured electromechanical systems, and with defect states such as nitrogen vacancy centers in diamond. The team will ultimately demonstrate how 1D/2D engineered arrays of non-reciprocal unit cells can create novel, reconfigurable, unidirectional pathways for sound. The general nature of this approach potentially makes it directly extensible into optical and electromagnetic domains in the future.

This research project combines electrical engineering, physics, and mechanical engineering, offering students a unique interdisciplinary training opportunity. The effort will also help broaden participation of women and minority students in research, and will lead to development of innovative educational and scientific outreach activities, with significant involvement of undergraduate students.

Recent News

Assistant Professors Verena Martinez Outschoorn and Liang Yang of the Department of Physics at the University of Illinois at Urbana-Champaign have each been selected for 2017 NSF CAREER Awards. The Faculty Early Career Development (CAREER) Award of the National Science Foundation is conferred annually in support of junior faculty who exemplify the role of teacher-scholars by integrating outstanding research with excellent education. Receipt of this honor also reflects great promise for a lifetime of leadership within recipients’ respective fields.

Mason says, “there are so few of us, people get the impression that we are like unicorns – either non-existent or magical.” We are far from non-existent, but I find women of color to be quite magical. However, as Jesse Williams says, “Just because we’re magic, doesn’t mean we’re not real.”

  • Outreach

It’s up to you and your team to save the free world from evil forces plotting its destruction, and you have precisely 60 minutes to do it. You must find out what happened to Professor Schrödenberg, a University of Illinois physicist who disappeared after developing a top-secret quantum computer that can crack any digital-security encryption code in the world.  Unfortunately, the previous groups of special agents assigned to the case disappeared while investigating the very room in which you now find yourself locked up, Schrödenberg’s secret lab.

LabEscape is a new science-themed escape room now open at Lincoln Square Mall in Urbana, testing the puzzle-solving skills of groups of up to six participants at a time. Escape rooms, a new form of entertainment cropping up in cities across the U.S. and around the globe, provide in-person mystery-adventure experiences that have been compared to living out a video-game or movie script. A team of participants is presented with a storyline and locked into a room with only one hour to find and decipher a sequence of interactive puzzles that will unlock the door and complete the mission. Two escape room businesses are already in operation in the area, C-U Adventures in Time and Space in Urbana and Brainstorm Escapes in Champaign.

 

  • Research
  • AMO/Quantum Physics
  • Condensed Matter Physics

Topological insulators, an exciting, relatively new class of materials, are capable of carrying electricity along the edge of the surface, while the bulk of the material acts as an electrical insulator. Practical applications for these materials are still mostly a matter of theory, as scientists probe their microscopic properties to better understand the fundamental physics that govern their peculiar behavior.

Using atomic quantum-simulation, an experimental technique involving finely tuned lasers and ultracold atoms about a billion times colder than room temperature, to replicate the properties of a topological insulator, a team of researchers at the University of Illinois at Urbana-Champaign has directly observed for the first time the protected boundary state (the topological soliton state) of the topological insulator trans-polyacetylene. The transport properties of this organic polymer are typical of topological insulators and of the Su-Schrieffer-Heeger (SSH) model.

Physics graduate students Eric Meier and Fangzhao Alex An, working with Professor Bryce Gadway, developed a new experimental method, an engineered approach that allows the team to probe quantum transport phenomena.