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Reciprocity is a fundamental symmetry in physics; in optics it can be understood as the principle of ‘if I can see you, you can see me’. Breaking this symmetry results in asymmetric information transfer between two systems, i.e., the transmission amplitudes change under the exchange of source and detector. In the optimal situation, information transfer only occurs in one direction, which is a highly valuable feature for quantum information processing, where one aims to read out a quantum system while protecting the signal source. The violation of the symmetry of reciprocity requires rather special conditions, and one may ask the question if there is a general way to break reciprocity between two systems. This is indeed possible, we find that one can construct nonreciprocal interactions by combining the appropriate coherent and dissipative dynamics. Our nonreciprocity concept was experimentally confirmed within an optomechanical array setup in a collaboration with Oscar Painter’s group at Caltech. Furthermore, a number of related experiments can essentially be mapped to our approach as well. Overall, the nonreciprocity protocol is a powerful tool for realize directional interactions between two quantum systems and its full potential has yet to be explored. In this talk I give an introduction of the basic concept on how to engineer nonreciprocal interactions and devices.

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Anja Metelmann, FU Berlin
Seminar Room 0.03, ETP
Contact: Sebastian Diehl