Research Topics:Quantum Magnetism:We study the phase diagrams, excitation spectra and thermodynamic properties of quantum magnets using numerical techniques such as Quantum Monte Carlo simulations and exact numerical diagonalization. Recently we have focused on impurity and field induced magnetic order in quantum spin liquids. Superconductivity:We are interested in unconventional superconductors and density wave states with nodal order parameters. Specifically, we are applying a generalized BCS mean field theory to understand the properties of cuprate, organic and heavy-fermion compounds. Recently, we have also been interested in Gossamer phenomena, i.e. the coexistence of two order unconventional parameters. Adaptive Quantum Design:We are developing adaptive quantum design algorithms to identify the best broken-symmetry spatial configurations of nanoscale building blocks such as atoms and molecules that enable desired target function responses. Recently, we have applied these techniques to tailor the quasiparticle density of states in atomic clusters, to achieve specific transmission profiles in dielectric structures for photonics, and to engineer many-body wave functions in quantum wells which can be used as excitonic modulators. Quantum Information Theory:Entanglement measures, such as the von-Neumann entropy, can be used to identify and characterize quantum phase transitions in many-body systems. In this project we examine the scaling behavior of the block entropy across quantum critical points using Quantum Monte Carlo. We also monitor how multi-partite entanglement compares with bipartite entanglement.
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