Speaker: Mahdis Ghodrati (ICTP-AP, Beijing)
Time: 2026-03-09 15:00-16:30
Location: 710, SIMIS
Zoom meeting ID: 836 6873 4651 Password: SIMIS
Abstract:
Based on an analogy with holographic confining geometries and using complexified fields, I introduce a holographic toy model of third order photonic exceptional points (EPs) of ternary coupled microrings with gain and loss, which makes an open, non-Hermitian quantum system. For this model, I discuss the Ferrell-Glover-Tinkham sum rule for various combinations of gain and loss systems, and show the numerical result for the behavior of spectra which matches with the experiments. In addition, I show the numerical behavior of phase rigidity and the Petermann factor around EPs versus various parameters of the model. I also discuss the connections between recent developments in complexified, time-dependent entanglement entropy and EPs, and finally, I connect EPs and the
θ-vacuum of QCD through topological structures, partition functions, and winding numbers, and show the presence of a second-order EP in a perturbed θ-vacuum model. If time permits, I will also discuss some other recent developments in the physics of EPs through holographic models.
About Speaker:
Mahdis Ghodrati is currently a postdoc from ICTP-AP, Beijing. He obtained his Bachelor degree from Sharif U. of Tech and then the Ph.D from University of Michigan, Ann Arbor. After that he became a postdoc at Yangzhou University, APCTP Pohang and ICTP-AP, Beijing.
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