Dimension Effects in Insulating NbTiN Disordered Films and the Asymptotic Freedom of Cooper Pairs

JETP Letters - We investigate the evolution of the electronic transport in disordered NbTiN films at the insulating side of the superconductor-insulator transition as function of the effective...     

Phase transitions in quantum pattern recognition

With the help of quantum mechanics one can formulate a model of associative memory with optimal storage capacity. This model is generalized by introducing a parameter playing the role of an effective temperature. The corresponding thermodynamics provides criteria to tune the efficiency of quantum pattern recognition. It is shown that the associative memory undergoes a phase transition from a disordered, high-temperature phase with no correlation between input and output to an ordered, low-temperature phase with minimal input-output Hamming distance.     

Superconductors with topological order

We propose a mechanism of superconductivity in which the order of the ground state does not arise from the usual Landau mechanism of spontaneous symmetry breaking but is rather of topological origin. The low-energy effective theory is formulated in terms of emerging gauge fields rather than a local order parameter and the ground state is degenerate on topologically non-trivial manifolds. The simplest example of this mechanism of superconductivity is concretely realized as global superconductivity in Josephson junction arrays.