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Sigurðsson Seminar
(or back to the Physics Seminars page)
- What? Time-Delay Polaritonics
- Who? Helgi Sigurðsson (University of Southampton).
Dr. Helgi Sigurðsson is a Research Fellow at the University of Southampton, School of Physics and Astronomy in the Hybrid Photonics group led by Prof. Pavlos Lagoudakis. He specializes in theoretical studies involving strong light-matter physics with a strong focus on exciton-polariton condensates. He received his BSc in physics from the University of Iceland in 2012 and PhD in Research Physics at the Nanyang Technological University, Singapore in 2016 under the supervision of Prof. Ivan Shelykh. From 2016 to 2018 he worked as a post-doctoral researcher at the University of Iceland under the supervision of Prof. Vidar Gudmundsson and Prof. Ivan Shelykh. His works involve realizing universal logic circuitry based on spatially manipulated exciton-polariton condensates, topological polaritonics, bifurcation points, numerical simulation of polariton condensate kinetics, artificial gauge fields for light-dressed electron states, and classical simulators for optimization tasks inspired by polariton condensate networks.
- Where? Wulfruna building (city campus), MA043a.
- When? Thursday 13th June, 16:00.
- Why? Helgi will overview recent advances in his research
- How? The talk is one hour and open to questions, tea & cookies will be provided.
- Chair: Anton Nalitov
Abstract: The field of polaritonics has experienced a dramatic growth due to being highly interdisciplinary and promising state-of-the-art devices with low power operation, fast signal processing capabilities, versatile control, room-temperature operation, and optical input-readout. The condensation of polaritons appears due to stimulated scattering into a high-gain state and is therefore fundamentally different from standard equilibrium Bose-Einstein condensation and sometimes referred as lasing without inversion. Conventionally, polariton condensates, and their equilibrium counterparts, are studied in trap geometries which restrict their phase space and allow easy study of complicated many body phenomena such as Josephson physics. However, in the inverse case, when polariton condensates are freely expanding from small (point-like) sources realized using tightly focused incoherent lasers they experience dynamics reminiscent of coupled semiconductor lasers with a time-delay.
In this lecture, I will present experimental results and an intuitive theoretical approach describing two spatially separated non-trapped polariton condensates, entitled the polariton dyad. The study provides evidence, for the first time, that interactions between non-trapped polariton condensates are approximately captured with coupled nonlinear time-delayed equations of motion, similar to the Lang-Kobayashi equation. A strong link between the field of polaritonics and semiconductor lasers is therefore established, and the potential of using polariton networks to simulate complex time delay problems in various sciences such as economics, epidemic outbreaks, traffic models, biology, etc., becomes possible. Of interest today are efficient devices which can emulate neurological functions which are naturally dictated by time delayed responses and history dependence.