Mohammad Ali Rajabpour: Formation probabilities, Post-measurement entanglement entropy and Casimir effect

I will first introduce formation probability as a quantity which can determine the universality class of a quantum critical system. In other words, by calculating this quantity one can find the central charge and critical exponents of a quantum system and determine the universality class uniquely. I will show that calculating this quantity boils down to finding Casimir energy of two needles. Then using boundary conformal field theory (BCFT) techniques we find exact results for the formation probabilities. Numerical results for transverse field Ising model will be presented to support the analytical results.  Then we will  briefly talk about Shannon mutual information as another quantity which can play similar role. We will present a conjecture which connects Shannon mutual information to the central charge of the underlying conformal field theory. We will support the conjecture  with many numerical calculations. Finally, we will introduce post-measurement entanglement entropy as a tripartite measure of entanglement. We will show that this quantity is related to the Casimir energy of needles on Riemann surfaces and can be calculated exactly for conformal field theories. To do that we use a slightly different method than twist operator technique. Many analytical results, such as, Renyi entropy, entanglement Hamiltonian, distribution of the eigenvalues of entanglement Hamiltonian, the effect of the boundary and Affleck-Ludwig boundary entropy can be discussed naturally in our framework.  Few numerical results regarding free bosons and transverse field Ising chain will be presented as support for analytical results.

* Mohammad Ali Rajabpour, Instituto de Fisica Universidade Federal Fluminense Niteroi, Rio de Janeiro

Szabolcs Vajna: Replica resummation of the Baker-Campbell-Hausdorff series

We developed a novel perturbative expansion for the effective Hamiltonian governing the dynamics of periodically kicked systems in the small parameter of the kick strength. The expansion is based on the replica trick, and is formally equivalent to the infinite resummation of the Baker-Campbell-Hausdorff series in the non-kicked Hamiltonian, while taking finite order terms in the kicks. As an application of the replica expansion, we study the heating properties of a periodically kicked spin chain. We demonstrate that even away from the high frequency driving limit, the heating rate is at least stretched exponentially suppressed in the kick strength. This leads to a long pre-thermal regime, where the dynamics is governed by the effective Hamiltonian obtained from the expansion.


* Szabolcs Vajna, Faculty of Mathematics and Physics, University of Ljubljana

Thomas Seligman: Conduction in realistic graphene related nano-structures: Tight bindng, Microwave experiments and outlook to many-body calculations

We present recent microwave experiments and corresponding tight binding calculations for acetylene and carbon nano-strips. In particular we focus on band gaps near the Dirac point and its sensitivity to the details of the connections. Finally we shall briefly discuss the perspectives of making effective many-body calculations by extending the techniques developed for the extension DFT-based programs to transport.

* Thomas Seligman, Centro Internacional de Ciencias, Cuernavaca

Gábor Takács: Dynamical confinement in out-of-equilibrium quantum systems

Non-equlibrium quantum systems have recently come to the fore in theoretical physics, mainly due to the rapid development of experimental techniques. The interest is partly motivated by fundamental theoretical problems: what are the conditions for a closed non-equilibrium quantum system to evolve towards an equilibrium, and what is the nature of an eventual equilibrium state? Another reason is that a large number of exotic quantum phenomena, hitherto only predicted or known theoretically, have been realised in the lab, which allows for directly comparing the models to physics reality. In this lecture I present a new result, which on the one hand points to a surprising phenomenon in the framework of an especially simple model. On the other hand it turned out that the findings are explained in terms of a statistical physics analogue of quark confinement known from the theory of strong interactions.

* Gábor Takács, Department of Theoretical Physics, Budapest University of Technology and Economics