We study the nature of an environment-induced exceptional point in a non-Hermitian pair of coupled mechanical oscillators. The mechanical oscillators are a pair of pillars carved out of a single isotropic elastodynamic medium made of aluminum and consist of carefully controlled differential losses. The interoscillator coupling originates exclusively from background modes associated with the “environment,” that portion of the structure which, if perfectly rigid, would support the oscillators without coupling. We describe the effective interaction in terms of a coupled-mode framework in which only one nearby environmental mode can qualitatively reproduce changes to the exceptional-point characteristics. Our experimental and numerical demonstrations illustrate strategic directions utilizing environmental mode control for the implementation of exceptional-point degeneracies. Potential applications include a new type of noninvasive differential atomic force microscopy and hypersensitive sensors for the structural integrity of surfaces.

Read the paper here: https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.13.01...

We are seeking a highly motivated postdoctoral fellow in the fields of mechanical engineering for a duration of 12 months in the wave dynamic lab (http://www.micromechanics.cn/en/) at Beijing Institute of Technology in China. Any candidates with strong experience in wave dynamics of periodic structures, metamaterials and soft structures are welcome. Gross salary 30,000USD annually.

Candidates should send their CV including a list of 3 references before 2016/06/15 to Prof. Gengkai Hu at hugeng@bit.edu.cn.