Waveguide QED: non-Markovian subradiance and interaction-induced quantum chaos | Prof. A. Poddubny

Prof. Alexander Poddubny, ITMO University, Ioffe Institute, Australian National University. Theoretical Seminar at The Department of Physics & Engineering, ITMO | 09/02/2020
"Waveguide QED: non-Markovian subradiance and interaction-induced quantum chaos"

Abstract: I will discuss two problems in the field of waveguide quantum electrodynamics (QED) studying propagating photons coupled to arrays of atoms or superconducting qubits. First, I will consider a periodic Bragg-spaced array of superconducting qubits. I will demonstrate that both photon bunching and anti-bunching persist at times that greatly exceed both radiative and non-radiative lifetimes of a single qubit. The correlations become immune to non-radiative dissipation due to the Borrmann effect, that is a strongly non-Markovian collective feature of light-qubit coupling inherent to the Bragg regime. Second, I will discuss interaction-induced chaotic states for photon pairs. I will show that nonparabolicity of the polariton dispersion enables a new mechanism of quantum chaos and nonintegrability. These results provide new insights in the interplay between order, chaos and localization in many-body quantum systems.

00:00:00 Introduction
00:02:05 Part I: non-Markovian subradiance
00:02:05 Bragg array of qubits
00:08:32 Markovian approximation
00:09:55 Question by Andrey Bogdanov
00:11:48 Question by Ivan Toftul
00:15:03 Transition from superradiant to photonic crystal regime
00:17:10 Question by Ivan Iorsh
00:19:34 Question by Mihail Petrov
00:26:33 Question by Ivan Iorsh
00:30:43 Question by Maxim Gorlach
00:31:08 Lifetime
00:34:48 Correlations g_2
00:37:17 Question by Maxim Gorlach
00:38:58 Part II: Quantum chaos induced by the interaction of two photons
00:39:48 Competition between order and chaos
00:41:29 Conception: two particles as plane waves and Bethe ansatz
00:48:28 Dispersion and isofrequency contours for polaritons
00:51:33 Bethe ansatz breaks
00:54:08 Question by Ivan Iorsh
00:58:38 Chaotic and non-chaotic states
00:59:21 Question by Maxim Gorlach
01:02:38 Conclusion, Questions, and discussion in the end

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