Dr Harald Schwefel, The Dodd-Walls Centre for Photonic and Quantum Technologies and Department of Physics, University of Otago, Dunedin, New Zealand
Leuchs-Russell Auditorium, A.1.500, Staudtstr. 2
Location details

Abstract:

Dielectric whispering-gallery-mode resonators are a great tool to entrap electro-magnetic radiation throughout the dielectric’s transparency range1. I will discuss hybrid systems which are resonant for both microwave and optical fields and that allow for second order nonlinear effects.

In an efficient resonant system and for strong microwave and optical fields, sum- and difference frequency generation can cascade, leading to optical frequency combs2. For the limit of very weak microwaves and only sum frequency generation, coherent conversion of microwave signals allows the quantum state of individual microwave photons to be transferred into the optical domain3, useful for connecting future superconducting-qubits-based quantum-networks. In my talk I will discuss our current results and address future direction including dual comb spectroscopy and quantum state conversion.

1    “Nonlinear and Quantum Optics with Whispering Gallery Resonators,” D.V. Strekalov, C. Marquardt, A.B. Matsko, H.G.L. Schwefel, and G. Leuchs, Journal of Optics 18, 123002 (2016).
2    “Resonant Electro-Optic Frequency Comb,” A. Rueda, F. Sedlmeir, M. Kumari, G. Leuchs, and H.G.L. Schwefel, Nature 568, 378 (2019).
3    “Efficient Microwave to Optical Photon Conversion: An Electro-Optical Realization,” A. Rueda, F. Sedlmeir, M.C. Collodo, U. Vogl, B. Stiller, G. Schunk, D.V. Strekalov, C. Marquardt, J.M. Fink, O. Painter, G. Leuchs, and H.G.L. Schwefel, Optica 3, 597 (2016).


Biography:
Harald Schwefel received his Ph.D. in theoretical physics from Yale University, USA. He has since worked as a postdoc at Yale, Japan, and as a group leader at the Max Planck Institute for the Science of Light, Germany. Since 2015 he is a Senior Lecturer at the Physics Department of the University of Otago, New Zealand and Principle Investigator of the Dodd-Walls Centre for Photonics and Quantum Technologies. His research interests are in nonlinear crystalline whispering gallery mode resonators, which he studies in the microwave