1,172 research outputs found
Slave Housing: In Search of Endangered Architecture
Although enslaved Africans constituted a significant majority of the population of Charleston County, South Carolina, from the early eighteenth century until the Civil War, only miniscule number of former slave houses survive. Intense analysis of the surviving slave houses at McLeod Plantation on James Island raises questions about what inherent aspects of their plan and construction constitutes what this study labels \u27slave architecture.\u27 The emergence, development and decline of slave houses reflects the broader history of slavery in the South Carolina Lowcountry and suggests that improved documentation of these rare buildings can play an important role in conveying the history of Charleston County\u27s antebellum black majority
Strongly interacting confined quantum systems in one dimension
In one dimension, the study of magnetism dates back to the dawn of quantum
mechanics when Bethe solved the famous Heisenberg model that describes quantum
behaviour in magnetic systems. In the last decade, one-dimensional systems have
become a forefront area of research driven by the realization of the
Tonks-Girardeau gas using cold atomic gases. Here we prove that one-dimensional
fermionic and bosonic systems with strong short-range interactions are solvable
in arbitrary confining geometries by introducing a new energy-functional
technique and obtaining the full spectrum of energies and eigenstates. As a
first application, we calculate spatial correlations and show how both ferro-
and anti-ferromagnetic states are present already for small system sizes that
are prepared and studied in current experiments. Our work demonstrates the
enormous potential for quantum manipulation of magnetic correlations at the
microscopic scale.Comment: 11 pages, 2 figures, including methods, final versio
Fractional energy states of strongly-interacting bosons in one dimension
We study two-component bosonic systems with strong inter-species and
vanishing intra-species interactions. A new class of exact eigenstates is found
with energies that are {\it not} sums of the single-particle energies with wave
functions that have the characteristic feature that they vanish over extended
regions of coordinate space. This is demonstrated in an analytically solvable
model for three equal mass particles, two of which are identical bosons, which
is exact in the strongly-interacting limit. We numerically verify our results
by presenting the first application of the stochastic variational method to
this kind of system. We also demonstrate that the limit where both inter- and
intra-component interactions become strong must be treated with extreme care as
these limits do not commute. Moreover, we argue that such states are generic
also for general multi-component systems with more than three particles. The
states can be probed using the same techniques that have recently been used for
fermionic few-body systems in quasi-1D.Comment: 6 pages, 4 figures, published versio
Multicomponent Strongly Interacting Few-Fermion Systems in One Dimension
The paper examines a trapped one-dimensional system of multicomponent
spinless fermions that interact with a zero-range two-body potential. We show
that when the repulsion between particles is very large the system can be
approached analytically. To illustrate this analytical approach we consider a
simple system of three distinguishable particles, which can be addressed
experimentally. For this system we show that for infinite repulsion the energy
spectrum is sixfold degenerate. We also show that this degeneracy is partially
lifted for finitely large repulsion for which we find and describe
corresponding wave functions.Comment: Paper in connection with the 22nd European Conference on Few-Body
Problems in Physics, Krakow, Poland, 9-13 September 201
Engineering the Dynamics of Effective Spin-Chain Models for Strongly Interacting Atomic Gases
We consider a one-dimensional gas of cold atoms with strong contact
interactions and construct an effective spin-chain Hamiltonian for a
two-component system. The resulting Heisenberg spin model can be engineered by
manipulating the shape of the external confining potential of the atomic gas.
We find that bosonic atoms offer more flexibility for tuning independently the
parameters of the spin Hamiltonian through interatomic (intra-species)
interaction which is absent for fermions due to the Pauli exclusion principle.
Our formalism can have important implications for control and manipulation of
the dynamics of few- and many-body quantum systems; as an illustrative example
relevant to quantum computation and communication, we consider state transfer
in the simplest non-trivial system of four particles representing
exchange-coupled qubits.Comment: 10 pages including appendix, 3 figures, revised versio
Bound states of Dipolar Bosons in One-dimensional Systems
We consider one-dimensional tubes containing bosonic polar molecules. The
long-range dipole-dipole interactions act both within a single tube and between
different tubes. We consider arbitrary values of the externally aligned dipole
moments with respect to the symmetry axis of the tubes. The few-body structures
in this geometry are determined as function of polarization angles and dipole
strength by using both essentially exact stochastic variational methods and the
harmonic approximation. The main focus is on the three, four, and five-body
problems in two or more tubes. Our results indicate that in the weakly-coupled
limit the inter-tube interaction is similar to a zero-range term with a
suitable rescaled strength. This allows us to address the corresponding
many-body physics of the system by constructing a model where bound chains with
one molecule in each tube are the effective degrees of freedom. This model can
be mapped onto one-dimensional Hamiltonians for which exact solutions are
known.Comment: 22 pages, 7 figures, revised versio
Initial data sets for the Schwarzschild spacetime
A characterisation of initial data sets for the Schwarzschild spacetime is
provided. This characterisation is obtained by performing a 3+1 decomposition
of a certain invariant characterisation of the Schwarzschild spacetime given in
terms of concomitants of the Weyl tensor. This procedure renders a set of
necessary conditions --which can be written in terms of the electric and
magnetic parts of the Weyl tensor and their concomitants-- for an initial data
set to be a Schwarzschild initial data set. Our approach also provides a
formula for a static Killing initial data set candidate --a KID candidate.
Sufficient conditions for an initial data set to be a Schwarzschild initial
data set are obtained by supplementing the necessary conditions with the
requirement that the initial data set possesses a stationary Killing initial
data set of the form given by our KID candidate. Thus, we obtain an algorithmic
procedure of checking whether a given initial data set is Schwarzschildean or
not.Comment: 16 page
High Pressure optical nanothermometer based on Er3+ photoluminescence
The optical properties of a sparsely investigated material, LaGdO3 doped with Er3+, are explored regarding its suitability as nanothermometer. Besides its excellent capabilities for dielectric applications, when doping with Er3+, this material provides a highly efficient upconversion photoluminescence (PL) for high temperature thermometry at high pressure due to its structural stability. LaGdO3 belongs to the perovskite-type ABO3 compounds with a B-type monoclinic C2/m space group (a = 14.43 Å; b = 3.69 Å; c = 9.00 Å; and ? = 100.70º) at ambient conditions. It undergoes a structural phase transition to a hexagonal ?3#?1 phase at 3GPa yielding a notable PL enhancement, thus enabling it as a potential high-pressure hightemperature nanothermometer.We acknowledge financial support from MAT2015-69508-P (MINECO/FEDER), MAT2015-71070-REDC; PGC2018-101464-B-I00 (MICIN/FEDER), IDIVAL 18/28, the European Research Council FET-OPEN NCLas H2020 Project (EU829161), and BSH Electrodomésticos España, S.A
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