Speaker Institution : Ruprecht Karls Universität Heidelberg
Title : Criticality in Quantum Long Range Systems
Abstract : The interest in long range interacting systems has recently raised due to their experimental realization in cold atom setups. Our investigation focuses on the derivation of the phase diagram and the critical exponents of weak long range interacting N components quantum rotor models (the N = 1 case being the quantum Ising model). Our picture is generic, non perturbative and it is valid for any spin components number $N$, spatial dimension $d$ and decay exponent $\sigma$. The phase diagram as a function of the decay exponent $\sigma$ is rich and the correlation functions are strongly anisotropic in the spatial and time domains. The results are in good agreement with Monte Carlo simulations and Density matrix renormalization group calculations pursued on quantum Ising and XY spin chains and also with spin systems coupled with an anomalous Bosonic bath.