Abstract: Recent experiments have resolved Yu-Shiba-Rusinov bound states induced by magnetic impurities (atoms or molecules) on NbSe2 superconductors. In our work, we show that it is possible to generate Majorana bound states localized at the ends of chains of ferromagnetic impurities on top of NbSe2. The robustness of topological phases is analyzed as a function of coupling strength between substrate and impurity, the orientation of the impurity chains on the superconductor, and the impurity spin direction.

Reference: D. Sticlet and C. Morari, Phys. Rev. B 100, 075420 (2019)

In theories of emergent gravity and holography the classical geometry of spacetime is arising from entanglement patterns of states of a conformal quantum field theory (CFT) living on its boundary. Using the AdS/CFT correspondence in this talk we elucidate how boundary entanglement patterns of the CFT vacuum are encoded into the bulk via the dynamics of a cluster algebra.
 

For a subdivision of the boundary into n parts the conditional mutual informations of overlapping boundary regions are mapped to triangulations of geodesic n-gons of the bulk. Such triangulations are mapped to tilings of kinematic space with causal diamonds. In this picture cluster dynamics is just a scanning of kinematic space by a seed pattern of such diamonds. We show that the space of all such tilings forms an associahedron, an object also known form recent studies of the theory of the S-matrix. Finally we observe that the flips relating the tilings are reminiscent of errors in an error correcting code.

The emerging field of phase-coherent caloritronics is based on the possibility of controlling heat currents by using the phase difference of the superconducting order parameter. The goal is to design and implement thermal devices that can control energy transfer with a degree of accuracy approaching that reached for charge transport by contemporary electronic components. This can be done by making use of the macroscopic quantum coherence intrinsic to superconducting condensates, which manifests itself through the Josephson effect and the proximity effect. The talk focuses on the first experimental realization of a heat interferometer.

Note the unusal time: 9:00!

A simple probe of chaos and operator growth in many-body quantum systems is the out of time ordered four point function. In a large class of local systems, the effects of chaos in this correlator build up exponentially fast inside the so called butterfly cone. It has been previously observed that the growth of these effects is organized along rays and can be characterized by a velocity dependent Lyapunov exponent. We prove a bound on this exponent that generalizes the chaos bound of Maldacena, Shenker and Stanford. We observe that many systems saturate this bound in a finite size region near the edge of the butterfly cone and the size of this region grows with the coupling. We discuss the connection to conformal Regge theory, where the velocity dependent exponent controls the four point function in an interpolating regime between the Regge and the light cone limit, and relate the aforementioned saturation of our bound to an exchange of dominance between the stress tensor and the pomeron.