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SUMMARY:Time-asymmetric metamaterials for a new degree of wave control
DTSTART:20150303T150000
DTEND:20150303T160000
DTSTAMP:20260506T134608Z
UID:ab3e3ecdcea5b2719b49816a227618d0f6fcc1c0773530395ea5fad4
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Romain Fleury\, Department of Electrical and Computer Engi
 neering\nUniversity of Texas\, Austin\nRomain Fleury is currently a Ph.D. 
 candidate in the department of Electrical and Computer Engineering at The 
 University of Texas at Austin\, where he is working with Professor Andrea 
 Alù on new interdisciplinary concepts in wave physics and engineering\, w
 ith an emphasis on metamaterials devices and metasurfaces. He received the
  M.S. in Engineering from Ecole Centrale de Lille\, France\, and the M.S. 
 in Micro and Nanotechnologies from the University of Lille\, France\, in 2
 010. During his Ph.D.\, he has published over 20 articles in peer-reviewed
  scientific journals\, including 15 first-author papers in journals such a
 s Science\, Physical Review Letters\, and Nature Communications. His work 
 on Non-Reciprocal Acoustics was featured on the cover of Science\, and att
 racted the attention of the general public\, with appearances in various m
 edia including NBC News\, Daily Mail\, and Scientific American. In 2014\, 
 he received the Best Student Paper award in Engineering Acoustics as well 
 as the Young Presenter Award in Noise from the Acoustical Society of Ameri
 ca. His research on Parity-Time symmetric metasurfaces has been awarded Be
 st Student Paper at the International Congress Metamaterials 2014 in Copen
 hagen\, Denmark.\nMetamaterials are artificially structured materials that
  are engineered to interact with waves in extraordinary ways\, leading to 
 unconventional physical phenomena not found in natural materials\, such as
  negative refraction and cloaking. They have been so far exclusively based
  on structures that are inherently symmetric upon time-reversal. In this t
 alk\, I will explore the largely uncharted properties of electromagnetic a
 nd acoustic metamaterials that are designed to purposely break time-revers
 al symmetry. First\, I will show how time-reversal symmetry breaking can b
 e exploited to build a novel class of non-reciprocal acoustic devices\, su
 ch as isolators and circulators. I will then use them as building blocks t
 o construct the acoustic equivalent of topological insulators\, a metamate
 rial that supports one-way phononic transport on its edges with strong top
 ological protection against defects and disorder. Second\, I will study th
 e exceptional properties of time-asymmetric systems that fulfill a special
  kind of space-time symmetry\, consisting in taking their mirror image and
  running time backwards. Known as Parity-Time (PT) symmetry\, this propert
 y leads to anomalous scattering behaviors such as unidirectional invisibil
 ity and phase compensation. I will demonstrate theoretically and experimen
 tally how PT-symmetric metasurface pairs can replicate electromagnetic phe
 nomena usually associated with bulk metamaterials\, like negative refracti
 on\, planar focusing and cloaking\, with the clear advantage of being comp
 letely loss-immune and potentially broadband.
LOCATION:ME B1 10 http://plan.epfl.ch/?lang=fr&room=ME+B1+10
STATUS:CANCELLED
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