Speaker: Manuel Meyer Department of Physics, Chemistry and Pharmacy University of Southern Denmark Abstract: The nature of dark matter continues to elude us, even after almost one century after first evidence for this non-luminous substance appeared. A leading hypothesis is that dark matter, which makes up more than 80% of all matter in the universe, consists of yet undiscovered fundamental particles. Such dark matter particles might interact feebly with known particles of the Standard Model, making them potentially detectable in the laboratory. The predicted low interaction rates require extremely sensitive detectors and ultra-low background levels. In this talk, I will discuss our recent progress in characterizing and improving the performance of transition edge sensors (TESs). Such TESs are planned to be used in the Any Light Particle (ALPS) II experiment, which searches for axions and axion-like particles. I will also review how we can use our TES to search for weakly interacting massive particles. With our ongoing research, we hope to achieve a new record for background suppression employing both optical filtering inside a cryostat as well as machine learning techniques while maintaining a quantum efficiency close to unity.  Location: D-IAS Aud. (V24-501a-0), Danish Institute for Advanced Study - DIAS. The event is open to all.

Speaker: Sergey I. Bozhevolnyi Center for Nano Optics University of Southern Denmark Abstract:Manipulation of single-photon emission from quantum emitters (QEs) has attracted a considerable attention in recent years due to its importance for quantum information technologies in quantum communication, computation, sensing and metrology. Here, recent progress in on-chip manipulation of the polarization, directionality and phase distribution in single-photon emission by making use of planar holographic QE-coupled metasurfaces is presented and discussed. The underlying idea is related to the concept of meta-atom, in which a QE is efficiently and non-radiatively coupled to surface modes, such as surface plasmon polaritons (SPPs), that are subsequently outcoupled into free propagating waves. An innovative metasurface design approach, vectorial scattering (computer-generated) holography, is introduced for the purpose of designing hybrid SPP-QE coupled metasurfaces suitable for generation of well-collimated beams of single photons with desirable polarization characteristics propagating along given directions. Latest results include its extension for realizing single-photon sources with radiation channels that exhibit diverse (including vectorial with spin and orbital angular momenta) wavefronts and polarization characteristics, opening thereby a way to generating quantum structured light in high dimensions. Location: D-IAS Aud. (V24-501a-0), Danish Institute for Advanced Study - DIAS. The event is open to all.