Quantum Hall phase emerging in an array of atoms interacting with photons | Dr. Alexander Poddubny

Dr. Alexander Poddubny, Theoretical Seminar at The Department of Physics & Engineering, ITMO | 04/01/2020
"Quantum Hall phase emerging
in an array of atoms
interacting with photons."
----
Abstract: Topological quantum phases underpin many concepts of modern physics. While the existence of disorder-immune topological edge states of electrons usually requires magnetic fields, the direct effects of the magnetic field on light are very weak. As a result, demonstrations of topological states of photons employ synthetic fields engineered in special complex structures or external time-dependent modulations. Here, we reveal that the quantum Hall phase with topological edge states, spectral Landau levels, and Hofstadter butterfly can emerge in a simple quantum system, where topological order arises solely from interactions without any fine-tuning. Such systems, arrays of two-level atoms (qubits) coupled to light being described by the classical Dicke model, have recently been realized in experiments with cold atoms and superconducting qubits. We believe that our findings will open new horizons in several disciplines including quantum physics, many-body physics, and nonlinear topological photonics, and it will set an important reference point for experiments on qubit arrays and quantum simulators.

0:00 Moderator: Dr.Maxim Gorlach
0:11:06 Comment from chat by Andrey Stepanenko "No y in last equation"
0:15:48 Question from chat by Dr. Maxim Gorlach "Ky is not multiplied by x?"
0:23:23 Question from the chat by Dr. Roman Saveliev "Why there is no Ax component?"
0:24:33 Question from the chat by Ivan Toftul: "Where do we take -2 psi_x from?'
0:24:53 Comment from Dr. Maxim Gorlach
0:29:33 Discussion with Dr. Alexey Yulin started
0:48:08 Question from Dr. Maxim Gorlach
0:53:08 Question from chat by Dr. Andrey Bogdanov "How do you measure the localization degree?"
0:55:18 Comment from Nikita Olekhno "IPR, inverse sum of components |V|^4 , 1/\sum_{m}\sum_{n}|\psi_{mn}|^4"
0:57:08 Question by Dr. Maxim Gorlach
1:03:08 Discussion with Dr. Maxim Gorlach
1:11:38 Question by Dr. Roman Saveliev

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