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SUMMARY: Time-asymmetric metamaterials for a new degree of wave control
DTSTART:20150303T150000
DTEND:20150303T160000
DTSTAMP:20260506T044834Z
UID:49c88044f0b6ab38b32ac0b0f96db8af96e83d85610cc7c1ece6bcc0
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Romain Fleury\, Department of Electrical and Computer Engi
 neering\, University 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\, 
 with an emphasis on metamaterials devices and metasurfaces. He received th
 e 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 
 2010. During his Ph.D.\, he has published over 20 articles in peer-reviewe
 d scientific journals\, including 15 first-author papers in journals such 
 as Science\, Physical Review Letters\, and Nature Communications. His work
  on Non-Reciprocal Acoustics was featured on the cover of Science\, and at
 tracted the attention of the general public\, with appearances in various 
 media 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 Amer
 ica. His research on Parity-Time symmetric metasurfaces has been awarded B
 est Student Paper at the International Congress Metamaterials 2014 in Cope
 nhagen\, Denmark.\nMetamaterials are artificially structured materials tha
 t are engineered to interact with waves in extraordinary ways\, leading to
  unconventional physical phenomena not found in natural materials\, such a
 s negative refraction and cloaking. They have been so far exclusively base
 d on structures that are inherently symmetric upon time-reversal. In this 
 talk\, I will explore the largely uncharted properties of electromagnetic 
 and acoustic metamaterials that are designed to purposely break time-rever
 sal symmetry. First\, I will show how time-reversal symmetry breaking can 
 be exploited to build a novel class of non-reciprocal acoustic devices\, s
 uch as isolators and circulators. I will then use them as building blocks 
 to construct the acoustic equivalent of topological insulators\, a metamat
 erial that supports one-way phononic transport on its edges with strong to
 pological protection against defects and disorder. Second\, I will study t
 he exceptional properties of time-asymmetric systems that fulfill a specia
 l kind of space-time symmetry\, consisting in taking their mirror image an
 d running time backwards. Known as Parity-Time (PT) symmetry\, this proper
 ty leads to anomalous scattering behaviors such as unidirectional invisibi
 lity and phase compensation. I will demonstrate theoretically and experime
 ntally how PT-symmetric metasurface pairs can replicate electromagnetic ph
 enomena usually associated with bulk metamaterials\, like negative refract
 ion\, planar focusing and cloaking\, with the clear advantage of being com
 pletely loss-immune and potentially broadband.
LOCATION:ME B1 10 http://plan.epfl.ch/?lang=fr&room=ME+B1+10
STATUS:CONFIRMED
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