6,082 research outputs found
Entanglement dynamics via coherent-state propagators
The dynamical generation of entanglement in closed bipartite systems is
investigated in the semiclassical regime. We consider a model of two particles,
initially prepared in a product of coherent states, evolving in time according
to a generic Hamiltonian, and derive a formula for the linear entropy of the
reduced density matrix using the semiclassical propagator in the coherent-state
representation. The formula is explicitly written in terms of quantities that
define the stability of classical trajectories of the underlying classical
system. The formalism is then applied to the problem of two nonlinearly coupled
harmonic oscillators and the result is shown to be in remarkable agreement with
the exact quantum measure of entanglement in the short-time regime. An
important byproduct of our approach is a unified semiclassical formula which
contemplates both the coherent-state propagator and its complex conjugate.Comment: 10 page
Decoherence induced by a phase-damping reservoir
A phase damping reservoir composed by -bosons coupled to a system of
interest through a cross-Kerr interaction is proposed and its effects on
quantum superpo sitions are investigated. By means of analytical calculations
we show that: i-) the reservoir induces a Gaussian decay of quantum coherences,
and ii-) the inher ent incommensurate character of the spectral distribution
yields irreversibility . A state-independent decoherence time and a master
equation are both derived an alytically. These results, which have been
extended for the thermodynamic limit, show that nondissipative decoherence can
be suitably contemplated within the EI D approach. Finally, it is shown that
the same mechanism yielding decoherence ar e also responsible for inducing
dynamical disentanglement.Comment: 8 pages, 3 figure
Slaves, Soldiers, Citizens: African American Artifacts of the Civil War Era
Based on the exhibit Slaves, Soldiers, Citizens: African American Artifacts of the Civil War Era, this book provides the full experience of the exhibit, which was on display in Special Collections at Musselman Library November 2012- December 2013. It also includes several student essays based on specific artifacts that were part of the exhibit.
Table of Contents:
Introduction Angelo Scarlato, Lauren Roedner ’13 & Scott Hancock
Slave Collars & Runaways: Punishment for Rebellious Slaves Jordan Cinderich ’14
Chancery Sale Poster & Auctioneer’s Coin: The Lucrative Business of Slavery Tricia Runzel ’13
Isaac J. Winters: An African American Soldier from Pennsylvania Who Fought at Petersburg Avery Lentz ’14
Basil Biggs: A Prominent African American in Gettysburg after the Battle Lauren Roedner ’13
Linton Ingram: A Former Slave Who Became a Notable African American Educator in Georgia Brian Johnson & Lincoln Fitch ’14
Uncle Tom’s Cabin Theatre Poster: Racism in Post-Emancipation Entertainment Michelle Seabrook ’13
Essay Bibliographies
Grand Army of the Republic
Exhibit Inventory
Acknowledgmentshttps://cupola.gettysburg.edu/libexhibits/1001/thumbnail.jp
Observation of strongly entangled photon pairs from a nanowire quantum dot
A bright photon source that combines high-fidelity entanglement, on-demand
generation, high extraction efficiency, directional and coherent emission, as
well as position control at the nanoscale is required for implementing
ambitious schemes in quantum information processing, such as that of a quantum
repeater. Still, all of these properties have not yet been achieved in a single
device. Semiconductor quantum dots embedded in nanowire waveguides potentially
satisfy all of these requirements; however, although theoretically predicted,
entanglement has not yet been demonstrated for a nanowire quantum dot. Here, we
demonstrate a bright and coherent source of strongly entangled photon pairs
from a position controlled nanowire quantum dot with a fidelity as high as
0.859 +/- 0.006 and concurrence of 0.80 +/- 0.02. The two-photon quantum state
is modified via the nanowire shape. Our new nanoscale entangled photon source
can be integrated at desired positions in a quantum photonic circuit, single
electron devices and light emitting diodes.Comment: Article and Supplementary Information with open access published at:
http://www.nature.com/ncomms/2014/141031/ncomms6298/full/ncomms6298.htm
Computation of energy exchanges by combining information theory and a key thermodynamic relation: Physical applications
Abstract By considering a simple thermodynamic system, in thermal equilibrium at a temperature T and in the presence of an external parameter A , we focus our attention on the particular thermodynamic (macroscopic) relation d U = T d S + δ W . Using standard axioms from information theory and the fact that the microscopic energy levels depend upon the external parameter A , we show that all usual results of statistical mechanics for reversible processes follow straightforwardly, without invoking the Maximum Entropy principle. For the simple system considered herein, two distinct forms of heat contributions appear naturally in the Clausius definition of entropy, T d S = δ Q ( T ) + δ Q ( A ) = C A ( T ) d T + C T ( A ) d A . We give a special attention to the amount of heat δ Q ( A ) = C T ( A ) d A , associated with an infinitesimal variation d A at fixed temperature, for which a "generalized heat capacity", C T ( A ) = T ( ∂ S / ∂ A ) T , may be defined. The usefulness of these results is illustrated by considering some simple thermodynamic cycles
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An injectable bone marrow-like scaffold enhances T cell immunity after hematopoietic stem cell transplantation.
Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for multiple disorders, but deficiency and dysregulation of T cells limit its utility. Here we report a biomaterial-based scaffold that mimics features of T cell lymphopoiesis in the bone marrow. The bone marrow cryogel (BMC) releases bone morphogenetic protein-2 to recruit stromal cells and presents the Notch ligand Delta-like ligand-4 to facilitate T cell lineage specification of mouse and human hematopoietic progenitor cells. BMCs subcutaneously injected in mice at the time of HSCT enhanced T cell progenitor seeding of the thymus, T cell neogenesis and diversification of the T cell receptor repertoire. Peripheral T cell reconstitution increased ~6-fold in mouse HSCT and ~2-fold in human xenogeneic HSCT. Furthermore, BMCs promoted donor CD4+ regulatory T cell generation and improved survival after allogeneic HSCT. In comparison to adoptive transfer of T cell progenitors, BMCs increased donor chimerism, T cell generation and antigen-specific T cell responses to vaccination. BMCs may provide an off-the-shelf approach for enhancing T cell regeneration and mitigating graft-versus-host disease in HSCT
An Optimal Decision Procedure for MPNL over the Integers
Interval temporal logics provide a natural framework for qualitative and
quantitative temporal reason- ing over interval structures, where the truth of
formulae is defined over intervals rather than points. In this paper, we study
the complexity of the satisfiability problem for Metric Propositional Neigh-
borhood Logic (MPNL). MPNL features two modalities to access intervals "to the
left" and "to the right" of the current one, respectively, plus an infinite set
of length constraints. MPNL, interpreted over the naturals, has been recently
shown to be decidable by a doubly exponential procedure. We improve such a
result by proving that MPNL is actually EXPSPACE-complete (even when length
constraints are encoded in binary), when interpreted over finite structures,
the naturals, and the in- tegers, by developing an EXPSPACE decision procedure
for MPNL over the integers, which can be easily tailored to finite linear
orders and the naturals (EXPSPACE-hardness was already known).Comment: In Proceedings GandALF 2011, arXiv:1106.081
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