Seminar: Zeros of the S-matrix of chaotic cavities with localized losses and Coherent Perfect Absorption: random matrix results

Speaker: Yan Fyodorov (King’s College London)

Time: WED, 11th October, 3.00 – 4.00 PM 

Venue: B21, School of Physics, University of Nottingham

Title: Zeros of the S-matrix of chaotic cavities with localized losses and Coherent Perfect Absorption: random matrix results

Abstract: Poles of the scattering S-matrix in the complex plane (a.k.a resonances) enjoyed extensive research in recent years, both in theory and experiments related to chaotic cavities. In contrast, their partners – complex zeroes of S-matrices – stayed in shadow. We show that those become relevant if one considers adding local absorbers to the cavity in order to realize a chaotic Coherent Perfect Absorbing (CPA) trap. We employ the Random Matrix Theory framework to calculate the density of zeroes of an M-channel scattering matrix describing a chaotic cavity with a single localized absorber embedded in it. Our approach extends beyond the weak-coupling limit of the cavity with the channels and applies for any absorption strength. It provides an insight for the optimal amount of loss needed to realize CPAs. Our predictions are tested against simulations for two types of traps: a complex network of resonators and quantum graphs. The presentation will be based on the joint work with T.Kottos and Suwun Suwunnarat, J.Phys. A vol. 50, 30LT01 (2017).