Aktuelle Veranstaltung für 24 Nov 2020
|Bert Koopmans, Eindhoven University of Technology, The Netherlands|
Femto-magnetism meets spintronics: Towards integrated magneto-photonics
|at Recording of the presentation|
16:15 Uhr s.t.
|Davide Racco, Perimeter Institute|
The low frequency part of the gravitational wave spectrum generated by local physics, such as a phase transition, is largely fixed by causality, offering a clean window into the early Universe. Due to the difference between sub-horizon and super-horizon physics, it is inevitable that there will be a distinct spectral feature that could allow for the direct measurement of the conformal Hubble rate at which the phase transition occurred. As an example, free-streaming particles present during the phase transition affect the production of super-horizon modes. This leads to a steeper decrease in the spectrum at low frequencies as compared to the well-known causal \(k^3\) super-horizon scaling of stochastic gravity waves. If a sizeable fraction of the energy density is in free-streaming particles, they even lead to the appearance of oscillatory features in the spectrum. If the universe was not radiation dominated when the waves were generated, a similar feature also occurs at the transition between sub-horizon to super-horizon causality. These features can be used to show surprising consequences, such as the fact that a period of matter domination following the production of gravity waves actually increases their power spectrum at low frequencies.
14:30 Uhr s.t., MITP seminar room
Wochenübersicht für die Woche 23 Nov 2020 bis 29 Nov 2020 (KW 48)
Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik
12:30 Uhr s.t., usually Staudingerweg 7, Minkowskiraum
|Viacheslav Filimonov, Institut für Physik|
Global Demonstrator and PFM module
|at Zoom for now|
Institut für Physik
13:00 Uhr s.t.
|Matteo Alfonsi, Institut für Physik, ETAP|
The XENON1T experiment has recently reported new results from the analysis of low energy electronic recoils data, characterized by the lowest background rate ever achieved in the energy range between 1 and 30 keV. An excess over known background has been observed around 2-3 keV, and this observation has been interpreted in terms of the existence of solar axions, or as an enhancement of the neutrino magnetic moment observed in solar neutrinos, or as an additional background initially not considered. In the latter hypothesis, among the various possibilities considered such as traces of 127Xe or 37Ar or tritium diluted into the active volume, only the tritium hypothesis cannot be confirmed or excluded with the current knowledge of the production and reduction mechanism. In this seminar I will describe the detector operation, the analysis approach and the arguments that allowed us to arrive to such conclusions, trying to address also the additional questions that has been posed by the community.
Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)
Institut für Physik
14 Uhr c.t.
|Dr. James Millen, King's College London, UK|
Nanoparticles suspended and cooled in vacuum are seen as ideal candidates for testing the limits of quantum mechanics, beyond state-of-the-art sensing, and tabletop detection of gravitational waves and dark matter. The standard technology involves optical trapping and levitation, though this comes with issues of optical absorption and photon scattering. Away from the optical regime, electromechanics concerns the control of mechanical motion via its coupling to an electrical circuit. Chip-based electromechanical systems are leading quantum technologies, allowing entanglement between different circuit-signals, quantum squeezing, and the coherent conversion of signals between different frequency regimes. I will present our preliminary results in the field of Levitated Electromechanics, where particles are levitated, detected and controlled all-electrically. I will introduce the concept of bath engineering in this system with a preliminary study of non-equilibrium dynamics, and our work towards miniaturization. For more information see www.levi-nano.com
GRK 2516 Soft Matter Seminar
10:30 Uhr s.t., via Zoom
|Thomas Hermans, University of Strasbourg, CNRS|
Liste der laufenden Seminare und Kolloquien
|Quantum Sonderseminar||Seminarraum Quantum (02-427)||Prof. Dr. Ferdinand Schmidt-Kaler|
|Technische Wartung: ducbao.ta (klammeraffe) uni-mainz.de|