Monday, March 21st 2022
17:15 get-together with coffee and snacks
Main Lecture Hall at TU Wien, Atominstitut, Stadionallee 2, 1020 Vienna
The seminar talk will be preceded by a VCQ Student talk at 17:45 by Miguel Gallego Ballester: Macroscopically nonlocal quantum correlations
Host: Markus Aspelmeyer
Due to the current Covid-situation, please don’t forget to wear your FFP2-mask at the Atominstitut and keep a 1-meter-distance during the get-together with coffee and snacks.
Abstract
The 'second quantum revolution' aims at exploiting coherence for novel technologies that will likely involve electromagnetic, mechanical, atomic, and topological degrees of freedom. Directional amplifiers, that amplify signals depending on the propagation direction, have recently attracted much attention, also for applications in quantum technologies. Here, I will present a unifying framework based on topology to understand non-reciprocity and directional amplification in driven-dissipative cavity arrays. Specifically, I will discuss a one-to-one correspondence between a non-zero topological invariant defined on the spectrum of the dynamic matrix and regimes of directional amplification, in which the end-to-end gain grows exponentially with the number of cavities. Time permitting, I will give a brief overview on our work on higher-order and fractional discrete time crystals in quantum and classical spin arrays.
Wanjura, C.C., Brunelli, M. & Nunnenkamp, A. Topological framework for directional amplification in driven-dissipative cavity arrays. Nat Commun 11, 3149 (2020). https://doi.org/10.1038/s41467-020-16863-9
Wanjura, C.C., Brunelli, M. & Nunnenkamp, A. Correspondence between non-Hermitian topology and directional amplification in the presence of disorder. Phys. Rev. Lett. 127, 213601 (2021). https://doi.org/10.1103/PhysRevLett.127.213601
Pizzi, A., Knolle, J. & Nunnenkamp, A. Higher-order and fractional discrete time crystals in clean long-range interacting systems. Nat Commun 12, 2341 (2021). https://doi.org/10.1038/s41467-021-22583-5
Andrea Pizzi, Andreas Nunnenkamp, and Johannes Knolle, Classical Prethermal Phases of Matter, Phys. Rev. Lett. 127, 140602 (2021). https://doi.org/10.1103/PhysRevLett.127.140602
