Ruggero Vaia

Research topics:
– Quantum fluctuations in finite-size systems
– Initialization of magnetic qubits by means of spin-chain solitons
– Optimal ballistic quantum-information transfer
– Magnetic impurities in 2D antiferromagnets
– Classical limit of the Ising model and of its quantum phase transition
– Field-tunable Kosterlitz-Thouless transition in 2D Heisenberg antiferromagnets
– 2D isotropic and anisotropic quantum Heisenberg antiferromagnets
– Effective Hamiltonian and critical temperature of 3D quantum Heisenberg magnets
– Coexisting Ising and Kosterlitz-Thouless transitions in the easy-plane Heisenberg antiferromagnet on the triangular lattice
– Kosterlitz-Thouless transition in 2D quantum magnets with easy-plane anisotropy
– Solitons in quantum spin chains with planar anisotropy and applied field
– Quantum statistical properties of 1D Heisenberg ferromagnets
– Path-integral theory of environmental coupling and reentrant enhancement of quantum fluctuations
– Quantum Monte Carlo for dissipative systems: low-T phase diagram of 2D Josephson-junction arrays with resistive shunts
– Effective potential for dissipative quantum systems
– Trotter-number extrapolation in quantum Monte Carlo simulations
– Quantum thermodynamics of rare-gas solids
– Effective classical Hamiltonian by the “pure-quantum self-consistent harmonic approximation” (PQSCHA)
– Quantum thermodynamics of pairs and chains of atoms with anharmonic interaction (Lennard-Jones, Toda, Morse)
– Classical effective potential and application to quantum nonlinear 1D models