TU BRAUNSCHWEIG

Welcome to the Institute of Mathematical Physics.

We investigate and describe aspects of quantum matter at low temperatures.

Prof. Christoph Karrasch's group investigates strong correlations in low-dimensional systems.

Prof. Patrik Recher's group focusses on the theory of quantum transport in low-dimensional systems.

Prof. Gertrud Zwicknagl's group studies strong correlations and cooperative effects in solids.

Upcoming talks

Tues. Jul. 23rd 2:00 pm in A318

Dynamical Quantum Phase Transitions in Topological Systems: Quasi-Disorder and Localization

Philipp Heilmann,

TU Dresden

Dynamical quantum phase transitions (DQPTs) have recently become a field of high interest in quantum many-body theory since experiments with ultra cold atoms and quantum simulators pave the way to explore properties of quantum states beyond the equilibrium paradigm. In my work I investigate the effects of quasi-disorder on DQPTs in topological systems. First, I briefly review DQPTs induced by quantum quenches in topological systems and I discuss the concept of a dynamical topological order parameter, constructed as a momentum space winding number of the Pancharatnam geometric phase. Then, I will introduce quasi-randomness by adding an incommensurate potential and point out that this leads to the emergence of mobility edges and a new quasi-localized phase. Furthermore, I discuss the phase diagrams for the topological and for the quasi-localized phase and present the results of quenches through this new landscape of phases.

Wed. Aug. 7th 10:00 am in A318

Electronic quantum transport in clean graphene devices

Dr. Ming-Hao Liu,

National Cheng Kung University (Tainan, Taiwan)

Electrons in clean graphene are known to behave like Dirac fermions due to its celebrated energy dispersion linear in momentum. Despite the discovery of graphene in 2004, devices of ultraclean samples with micron-scale mean free paths became accessible only recently. Reliable quantum transport simulations in the ballistic regime have become an important guiding tool for understanding and predicting novel transport experiments. In this talk, simple keys to quantum transport simulations for clean graphene devices [1] will be briefly introduced. A few selected topics simulating real graphene devices will be summarized to show the power of the introduced method. Finally, recent works on graphene superlattices [2] and decoupled twisted bilayer graphene [3] will be discussed.

[1] M.-H. Liu et al., Phys. Rev. Lett. 114, 036601 (2015)
[2] P. Rickhaus et al., arXiv:1907.00582
[3] S.-C. Chen et al., arXiv:1907.03288


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