Berlin 2018 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 69: Poster: Quantum Systems
DY 69.10: Poster
Donnerstag, 15. März 2018, 15:30–18:00, Poster A
Microwave graphs with time-dependent perturbations — •Tobias Hofmann1, Aimaiti Rehemanjiang1, Ulrich Kuhl1,2, and Hans-Jürgen Stöckmann1 — 1Fachbereich Physik der Philipps-Universität Marburg, D-35032 Marburg, Germany — 2Université Côte d’Azur, CNRS, Institut de Physique de Nice, 06108 Nice, France
The study of microwave billiards, where one Parameter depends on time, always has been a challenge.
One possible parameter is the coupling to an external channel, which we have specifically in mind here.
The difficulties arise from the need to apply perturbations of
sufficient strength with frequencies of the order of the mean level
spacing, typically of some MHz to be in the interesting regime.
In microwave networks time variations can be achieved by a means of a T junction, where one port is connected to a cable with a changeable terminator. A wave traveling through the cable being reflected at the end and returning to the T junction acquires a phase given by Δϕ=2kl+ϕterm, where k=2πν/c is the wave number, l the cable length and ϕterm is the reflection phase. The expected periodic variation of the transmission from port 1 to port 2 with frequency ν was experimentally verified. If now the terminator of the cable is replaced by a variable diode, ϕterm may be changed continuously by means of the diode voltage. Periodic modulations of the transmission with frequencies up to 10 MHz have already been achieved. By applying stochastic time variations also the study of “noisy graphs” [1] become feasible.
[1] D. Waltner, U. Smilansky, J. Phys. A 47, 355101 (2014).