Marc Dubois, UC Berkeley

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Marc Dubois will give a seminar "Accessing the exceptional points of parity-time symmetric acoustics" on December 15 at 02:00 p.m., room Pierre Cotton (groundfloor of the Lab), on Campus St Jérome, Marseille

Abstract :

Parity-time (PT) symmetric concept and development lead to a wide range of applications including coherent perfect absorbers, single mode lasers, unidirectional cloaking and sensing, and optical isolators. These new applications and devices emerge from the existence of a phase transition in PT symmetric complex-valued potential obtained by balancing gain and loss materials. Besides the observation of these new properties, the systematic development of PT symmetric devices is adjourned by the lack of control over the PT phase and phase transition. Consequently, the key practical challenge resides in the management of the complex scattering process within the PT symmetric structure in order to engineer PT phase and exceptional points. Here, we demonstrate a method to tame the phase and exceptional points of PT symmetric devices. Our experimental demonstration is based on an active acoustic element that realizes a complex-valued potential and simultaneously controls the multiple interference inside the structure at any given frequency. This method broadens the scope of applications for PT symmetric devices in many fields including optics, microwaves, electronics, which are crucial for sensing, imaging, cloaking, lasing, absorbing etc.

Further information :
[1] X Zhu, H Ramezani, C Shi, J Zhu, X Zhang, "PT-Symmetric Acoustics", PRX, 4, 031042 (2014)
[2] C Shi, M Dubois, Y Chen, L Cheng, H Ramezani, Y Wang, X Zhang,” Accessing the exceptional points of parity-time symmetric acoustics” Nat Comm, 7, 1-5 (2016)

Contact : Marc Dubois, Postdoc Zhang Lab, University of California, Berkeley, USA