Related papers: Ground State Wave Function Overlap in Superconduct…
The two-dimensional $t$-$J$ model in the ground state is investigated by the power Lanczos method. The pairing-pairing correlation function for $d_{x^2-y^2}$-wave symmetry is enhanced in the realistic parameter regime for high-$T_c$…
Supersymmetry plays a main role in all current thinking about superstring theory. Indeed, many remarkable properties of string theory have been explained using supersymmetry as a tool. In this dissertation, we review the basic formulation…
The ground-state phase properties of a two-dimensional Bose system with dipole-dipole interactions is studied by means of quantum Monte Carlo techniques. Limitations of mean-field theory in a two-dimensional geometry are discussed. A…
We analyze a class of quantum-critical models, in which momentum integration and the selection of a particular pairing symmetry can be done explicitly, and the competition between non-Fermi liquid and pairing can be analyzed within an…
This paper consists of three parts. In part I, we microscopically derive Ginzburg--Landau (GL) theory from BCS theory for translation-invariant systems in which multiple types of superconductivity may coexist. Our motivation are…
The ground state properties of the S=1/2 transverse-field Ising model on the checkerboard lattice are studied using linear spin wave theory. We consider the general case of different couplings between nearest neighbors (J1) and…
In this letter, we study the ground state of two spherical macroions of identical radius, but asymmetric bare charge ((Q_{A}>Q_{B})). Electroneutrality of the system is insured by the presence of the surrounding divalent counterions. Using…
We study a system of penetrable bosons embedded in a spherical surface. Under the assumption of weak interaction between the particles, the ground state of the system is, to a good approximation, a pure condensate. We employ thermodynamic…
Systematic investigation of the accuracy of the description of the energies of deformed one-quasiparticle states has been performed in covariant density functional theory in actinide and rare-earth mass regions. The sources of the…
It is well established that superconductivity is based on a coherent quantum state of Cooper pairs with charge 2e, and this is equally true of the Josephson effect. In contrast, Kadin recently presented an alternative real-space model of…
The phase conjugation of an unknown Gaussian state cannot be realized perfectly by any physical process. A semi-classical argument is used to derive a tight lower bound on the noise that must be introduced by an approximate phase…
We propose a new class of ground states for doped Mott insulators in the electron second-quantization representation. They are obtained from a bosonic resonating valence bond (RVB) theory of the t-J model. At half filling, the ground state…
We examine the superfluid phase of a hard-core boson model with nearest-neighbor exchange J and four-particle ring-exchange K at half-filling on the square lattice. At zero temperature we find that the superfluid in the pure-J model is…
We set up the effective field theories which describe the SO(5)-invariant picture of the high-Tc cuprates in various regimes. We use these to get quantitative conclusions concerning the size of SO(5)-breaking effects. We consider two…
Since the first experimental realization of Bose-Einstein condensates in a spin-orbit-coupled Zeeman lattice, a wide range of applications have been found in these systems. Here, we systematically study the ground-state phase diagram of the…
Systems showing resonant superfluidity, driven by an exchange coupling of strength $g$ between uncorrelated pairs of itinerant fermions and tightly bound ones, undergo a first order phase transition as $g$ increases beyond some critical…
We develop a variational wave function for the ground state of a one-dimensional bosonic lattice gas. The variational theory is initally developed for the quantum rotor model and later on extended to the Bose-Hubbard model. This theory is…
Superconductivity (SC) may microscopically coexist with density wave (DW) when the nesting of the Fermi surface (FS) is not perfect. There are, at least, two possible microscopic structures of a DW state with quasi-particle states remaining…
Bose-Einstein condensation and the $\lambda$-transition are described in molecular detail for bosons interacting with a pair potential. New phenomena are identified that are absent in the usual ideal gas treatment. Monte Carlo simulations…
Twenty-five years after the first proposal, the question whether the ground state of a frustrated spin-half system is well described by a spin-liquid Resonating Valence Bond (RVB) wave function is still controversial. A physically…