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T. Milburn, J. Doppler, C. Holmes, S. Portolan, A. Girschik, F. Libisch, A. Mailybaev, P. Rabl, S. Rotter:
"General description of quasi-adiabatic dynamical phenomena near exceptional points";
Talk: 13th Workshop on Physics with Non-Hermitian Operators (PHHQP13), Jerusalem (invited); 2015-07-12 - 2015-07-16.

The appearance of so-called exceptional points in the complex spectra of non-Hermitian systems is often associated with phenomena that contradict our physical intuition. One example of particular interest is the state-exchange process predicted for an adiabatic encircling of an exceptional point [1]. In my talk I will discuss this process for the generic system of two coupled oscillator modes with loss or gain [2]. We identify a characteristic system evolution consisting of periods of quasi-stationarity interrupted by abrupt non-adiabatic transitions. Our findings explain the breakdown of the adiabatic theorem as well as the chiral behavior noticed previously in this context [3, 4] through the switching between two fixed points in the dynamics and the phenomenon of stability loss delay. The framework we set up to describe these effects provides a unified approach to model quasi-adiabatic dynamical effects in non-Hermitian systems in a qualitative and quantitative way. Finally, I will also discuss potential realizations of these concepts in real-world devices with promising properties.

References:
[1] C. Dembowski, H.-D. Gräf, H. L. Harney, A. Heine, W. D. Heiss, H. Rehfeld, and A. Richter, Phys. Rev. Lett. 86, 787 (2001).
[2] T. J. Milburn, J. Doppler, C. A. Holmes, S. Portolan, S. Rotter, and P. Rabl, arXiv:1410.1882v2
[3] M. V. Berry and R. Uzdin, J. Phys. A: Math. Theor. 44, 435303 (2011).
[4] I. Gilary, A. A. Mailybaev, and N. Moiseyev, Phys. Rev. A 88, 010102(R) (2013).