1,038 research outputs found
Adiabatic Tracking of a State: a New Route to Nonequilibrium Physics
We present a novel numerical approach to track the response of a quantum
system to an external perturbation that is progressively switched-on. The
method is applied, within the framework of the density matrix renormalization
group technique, to track current-carrying states of interacting fermions in
one dimension and in presence of an Aharonov-Bohm magnetic flux. This protocol
allows us to access highly excited states. We also discuss the connection with
the entanglement entropy of these excited states
Emergence of One-Dimensional Physics from the Distorted Shastry-Sutherland Lattice
Motivated by the on-going investigation of SrCu(BO) under
pressure, we study a variant of the two-dimensional Shastry-Sutherland (SS)
spin-1/2 model with two types of dimers. Combined with the frustration of the
SS model, this modification induces, in a large parameter range, a dimensional
reduction at low energies, with nearly decoupled effective S=1 Haldane chains
forming along one of the diagonals of the lattice. We also present evidence
that the intermediate plaquette solid phase of the undistorted SS model remains
stable in a finite region of the phase diagram.Comment: 4 pages, 5 figure
Quantum phase transitions in multileg spin ladders with ring exchange
Four-spin exchange interaction has been raising intriguing questions
regarding the exotic phase transitions it induces in two-dimensional quantum
spin systems. In this context, we investigate the effects of a cyclic four-spin
exchange in the quasi-1D limit by considering a general N-leg spin ladder. We
show by means of a low-energy approach that, depending on its sign, this ring
exchange interaction can engender either a staggered or a uniform dimerization
from the conventional phases of spin ladders. The resulting quantum phase
transition is found to be described by the SU(2)_N conformal field theory. This
result, as well as the fractional value of the central charge at the
transition, is further confirmed by a large-scale numerical study performed by
means of Exact Diagonalization and Density Matrix Renormalization Group
approaches for N \le 4
Magnetization plateaux in the classical Shastry-Sutherland lattice
We investigated the classical Shastry-Sutherland lattice under an external
magnetic field in order to understand the recently discovered magnetization
plateaux in the rare-earth tetraborides compounds RB. A detailed study of
the role of thermal fluctuations was carried out by mean of classical spin
waves theory and Monte-Carlo simulations. Magnetization quasi-plateaux were
observed at 1/3 of the saturation magnetization at non zero temperature. We
showed that the existence of these quasi-plateaux is due to an entropic
selection of a particular collinear state. We also obtained a phase diagram
that shows the domains of existence of different spin configurations in the
magnetic field versus temperature plane.Comment: 4 pages, proceedings of HFM200
Competing superconducting instabilities in the one-dimensional p-band degenerate cold fermionic system
The zero-temperature phase diagram of -orbital two-component fermionic
system loaded into a one-dimensional optical lattice is mapped out by means of
analytical and numerical techniques. It is shown that the -band model away
from half-filling hosts various competing superconducting phases for attractive
and repulsive interactions. At quarter filling, we analyze the possible
formation of incompressible Mott phases and in particular for repulsive
interactions, we find the occurrence of a Mott transition with the formation of
fully gapped bond-ordering waves.Comment: published versio
Symmetry-protected topological phases of alkaline-earth cold fermionic atoms in one dimension
We investigate the existence of symmetry-protected topological phases in
one-dimensional alkaline-earth cold fermionic atoms with general half-integer
nuclear spin I at half filling. In this respect, some orbital degrees of
freedom are required. They can be introduced by considering either the
metastable excited state of alkaline-earth atoms or the p-band of the optical
lattice. Using complementary techniques, we show that SU(2) Haldane topological
phases are stabilised from these orbital degrees of freedom. On top of these
phases, we find the emergence of topological phases with enlarged SU(2I+1)
symmetry which depend only on the nuclear spin degrees of freedom. The main
physical properties of the latter phases are further studied using a
matrix-product state approach. On the one hand, we find that these phases are
symmetry-protected topological phases, with respect to inversion symmetry, when
I=1/2,5/2,9/2,..., which is directly relevant to ytterbium and strontium cold
fermions. On the other hand, for the other values of I(=half-odd integer),
these topological phases are stabilised only in the presence of exact
SU(2I+1)-symmetry
Environmental Sustainability and the Hospitality Customer Experience: A Study in Tourist Accommodation
Academic research on sustainability in the hospitality industry is scarce and fragmented, and requires a general structure to lend coherence to its approach. There is a need for empirical research to fathom the question of environmental sustainability and customer experience in the hospitality industry and to study the interaction between the two concepts. This paper aims to close these gaps by establishing the nature of the relationship between customers’ perceptions of the environmental practices in tourism accommodation and their customer experiences and levels of satisfaction. The working hypotheses, based on a review of the literature on environmental sustainability and customer experience in the hospitality industry, are tested in an empirical study of 412 Spanish customers who stayed in various types of tourist accommodation. The main conclusion is that the relationship between environmental sustainability and customer experience in the hospitality industry can be demonstrated. This paper also validates a measurement scale based on the most accepted dimensionality of the construct: cognitive (think), affective (feel), behavioral (act), sensory (sense) and social (relate)
Variation propagation of bench vises in multi-stage machining processes
ComunicaciĂłn presentada a MESIC 2019 8th Manufacturing Engineering Society International Conference (Madrid, 19-21 de Junio de 2019)Variation propagation has been successfully modeled by the Stream of Variation (SoV) approach in multistage machining processes. However, the SoV model basically supports 3-2-1 fixtures based on punctual locators and other workholding systems such as conventional vises are not considered yet. In this paper, the SoV model is expanded to include the fixture- and datum-induced variations on workholding devices such as bench vises. The model derivation is validated through assembly and machining simulations on Computer Aided Design software. The case study analyzed shows an average error of part quality prediction between the SoV model and the CAD simulations of 0.26%
Influence of lattice distortions in classical spin systems
We investigate a simple model of a frustrated classical spin chain coupled to
adiabatic phonons under an external magnetic field. A thorough study of the
magnetization properties is carried out both numerically and analytically. We
show that already a moderate coupling with the lattice can stabilize a plateau
at 1/3 of the saturation and discuss the deformation of the underlying lattice
in this phase. We also study the transition to saturation where either a first
or second order transition can occur, depending on the couplings strength.Comment: Submitted to Phys. Rev.
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