主讲人：Barbara Dietz

　　时间：2018年4月3日 10：00

　　地点：理学院206报告厅

　　主办：理学院

　　主讲人简介：Barbara Dietz is currently a full professor of physics at Lanzhou University (兰州大学). She is originally from Germany, where she received her PhD in Physics from the University of Duisburg-Essen (杜伊斯堡-埃森 大学). She has been research associate at the Technical University of Darmstadt （达姆施塔特理工大学) for over 15 years, after which she moved to the Polish Academy of Sciences (波兰科学院) as an assistant professor. She has been working in China since 2016. Her research includes both theoretical and experimental work in quantum chaos, dealing in particular with quantum scattering, random matrix theory, and microwave cavities. More recently, she has also been working on the experimental realization of artificial graphene, as well as on quantum networks.

　　主讲内容：First I will give a brief introduction on aspects of Quantum Chaos, that is, on the study of manifestations of classical chaos in the spectral fluctuation properties of the corresponding quantum system. Then I will report on the investigation of the fluctuations in the spectra of microwave networks simulating quantum graphs with classically chaotic dynamics and preserved or violated time-reversal invariance. Such systems are especially suited for the theoretical and experimental study of various aspects related with wave chaos, random matrix theory and the semiclassical approach. Both closed and open quantum systems with and without time-reversal invariance violation may be designed.

　　In the experimental spectra approximately 6% of the levels are missing. However, the statistical analysis of the spectral properties of a quantum system and the comparison with those of random matrices from the conventional results for Gaussian ensembles requires complete sequences of eigenvalues belonging to the same symmetry class. We will present a procedure [1-3], to determine the fraction of missing levels and still unambiguously identify the symmetries from the spectral properties of the corresponding quantum system. Incomplete spectra are actually a problem one has to cope with in real physical systems, like, e.g., nuclei, dielectric and microwave cavities. Thus, such a procedure is a requisite for their analysis.

References

[1] M. Białous et al., Phys. Rev. E 94, 042211 (2016).

[2] M. Białous et al., Phys. Rev. Lett. 117, 144101 (2016).

B. Dietz et al., Phys. Rev. E 95, 052202 (2017).