The description of the properties of liquid Helium is a challenge for any microscopic many–body theory. In this context, we study the ground state and the excitation spectrum of one He impurity in liquid He at T = 0 with the aim of illustrating the power of the correlated basis function formalism in describing heavily correlated systems. The strong interatomic interaction and the large density ...

It is shown that the homogeneous cooling state (HCS) for a heavy impurity particle in a granular fluid supports two distinct phases. The order parameter straight phi;(s) is the mean square velocity of the impurity particle relative to that of a fluid particle, and the control parameter xi* is the fluid cooling rate relative to the impurity collision rate. For xi*<1 there is a "normal" phase for...

We have measured the concentration dependence of the transmission conduction electron spin resonance linewidth of copper doped with Li, Zn, Ga, Ge, As, Ni, and Ti. In each case, we find a linear concentration dependence which allows us to determine a spin-flip cross-section, 03C3sf, for each impurity. These crosssections, together with those deduced from linewidth data previously published for ...

We study electron transport in nanojunctions in which an electron on a quantum dot or a molecule is interacting with an N-state local impurity, a harmonic ("Holstein") mode, or a two-state system ("spin"). These two models, the Anderson-Holstein model and the spin-fermion model, can be conveniently transformed by a shift transformation into a form suitable for a perturbative expansion in the tu...

In a recent experiment, signatures of Majorana fermion (MF) were found in the vortex core threading a heterostructure composed of n layers of topological insulator (TI) deposited on a bulk s-wave superconductor. Here we provide strong theoretical support to the experiment. First, we demonstrate that MF modes appear on both top and bottom layers of TI, and are well separated for n ~ 6. The top M...

It is shown that the calculation of the magnetic moment of a Friedel-Anderson impurity in mean-field theory is unreliable. A class of approximate solutions, which contains the mean-field solution as an element, is expressed in rotated Hilbert space and optimized. The optimal state has considerably lower energy than the mean field solution and requires almost twice the Coulomb exchange U to beco...

Recent scanning tunnelling microscopy (STM) experiments on underdoped cuprates have displayed modulations in the local electronic density of states which are centered on a Cu-O-Cu bond (Kohsaka et al., Science 315, 1380 (2007)). As a paradigm of the pinning of such bond-centered ordering in strongly correlated systems, we present the theory of valence bond solid (VBS) correlations near a single...

When an impurity interacts with a bath of phonons it forms a polaron. For increasing interaction strengths the mass of the polaron increases and it can become self-trapped. For impurity atoms inside an atomic Bose-Einstein condensate (BEC) the nature of this transition is not understood. While Feynman's variational approach to the Fröhlich model predicts a sharp transition for light impurities,...

The numerical renormalization group method (NRG) has been developed by Wilson in the 1970's to investigate the Kondo problem. The NRG has since then been applied to the calculation of static and dynamic properties of a variety of impurity models, in particular in the very low temperature regime. These investigations lead to a deeper understanding of the physics of magnetic impurities in a free ...

Quantum spin-orbital liquids are elusive strongly correlated states of matter that emerge from quantum frustration between spin and orbital degrees of freedom. A promising route towards the observation of those states is the creation of artificial Mott insulators where antiferromagnetic correlations between spins and orbitals can be designed. We show that Coulomb impurity lattices on the surfac...