11,289 research outputs found
Quasideterministic generation of maximally entangled states of two mesoscopic atomic ensembles by adiabatic quantum feedback
We introduce an efficient, quasideterministic scheme to generate maximally
entangled states of two atomic ensembles. The scheme is based on quantum
nondemolition measurements of total atomic populations and on adiabatic quantum
feedback conditioned by the measurements outputs. The high efficiency of the
scheme is tested and confirmed numerically for ideal photodetection as well as
in the presence of losses.Comment: 7 pages, 6 figures, title changed, revised version published on Phys.
Rev
Berry phase correction to electron density of states in solids
Liouville's theorem on the conservation of phase space volume is violated by
Berry phase in the semiclassical dynamics of Bloch electrons. This leads to a
modification of the phase space density of states, whose significance is
discussed in a number of examples: field modification of the Fermi-sea volume,
connection to the anomalous Hall effect, and a general formula for orbital
magnetization. The effective quantum mechanics of Bloch electrons is also
sketched, where the modified density of states plays an essential role.Comment: Minor revision. Journal info updat
Statistical Mechanics of Steiner trees
The Minimum Weight Steiner Tree (MST) is an important combinatorial
optimization problem over networks that has applications in a wide range of
fields. Here we discuss a general technique to translate the imposed global
connectivity constrain into many local ones that can be analyzed with cavity
equation techniques. This approach leads to a new optimization algorithm for
MST and allows to analyze the statistical mechanics properties of MST on random
graphs of various types
Hospitality Spaces, Hospitable Moments: Consumer Encounters and Affective Experiences in Commercial Settings
This paper examines the production of hospitable experiences within consumer encounters in commercial hospitality spaces. It considers the different dimensions or forms of hospitality and distinguishes between the offer of food, drink, shelter and entertainment within commercial transactions, the offer of hospitality as a means of achieving social or political goals, and meta-hospitality – temporary states of being that are different from the rational manifestations of hospitality. It is argued that meta-hospitality is tied to communitesque moments – short-lived emotional bonds that may be built or experienced through hospitality transactions. A case study is used to identify three factors that shape the development of communitesque experiences – the ecology in which it occurs, the participants' roles and their capabilities
A Discrete Time Presentation of Quantum Dynamics
Inspired by the discrete evolution implied by the recent work on loop quantum
cosmology, we obtain a discrete time description of usual quantum mechanics
viewing it as a constrained system. This description, obtained without any
approximation or explicit discretization, mimics features of the discrete time
evolution of loop quantum cosmology. We discuss the continuum limit, physical
inner product and matrix elements of physical observables to bring out various
issues regarding viability of a discrete evolution. We also point out how a
continuous time could emerge without appealing to any continuum limit.Comment: 20 pages, RevTex, no figures. Additional Clarifications added.
Version accepted for publication in Class. Quant. Gra
MR-Guided Laser Interstitial Thermal Therapy for Treatment of Brain Tumors
Minimally invasive technologies for intracranial lesions are a rapidly growing area of surgical neuro-oncology. Magnetic resonance (MR)-guided laser interstitial thermal therapy (LITT) is novel adjunctive therapy for patients who are poor candidates for open surgical resection. Recent developments in modern stereotaxy, fiber optics, and MR thermography imaging have improved the safety profile of LITT, enabling its emergence as an attractive alternative adjunct therapy for intracranial lesions which are deep-seated, refractory to standard therapies, or in patients with multiple comorbidities. In this chapter, we review the technological principles underlying LITT and provide a comprehensive, up-to-date summary of the evidence regarding the indications, outcomes, and limitations of LITT for a diverse array of intracranial tumors, including dural-based lesions, metastases, gliomas, and radiation necrosis
Critical charge instability on verge of the Mott transition and the origin of quantum protection in high- cuprates
The concept of topological excitations and the related ground state
degeneracy are employed to establish an effective theory of the superconducting
state evolving from the Mott insulator for high-Tc cuprates. Casting the
Coulomb interaction in terms of composite-fermions via the gauge flux
attachment facility, we show that instanton events in the Matsubara "imaginary
time," labeled by topological winding numbers, are essential configurations of
the phase field dual to the charge. In analogy to the usual phase transition
that is characterized by a sudden change of the symmetry, the topological phase
transitions are governed by a discontinuous change of the topological numbers
signaled by the divergence of the zero-temperature topological susceptibility.
This defines a quantum criticality ruled by topologically conserved numbers
rather than the Landau principle of the symmetry breaking. We show that in the
limit of strong correlations topological charge is linked to the average
electronic filling number and the topological susceptibility to the electronic
compressibility of the system. We exploit the impact of these nontrivial U(1)
instanton phase field configurations for the cuprate phase diagram which
displays the "hidden" quantum critical point covered by the superconducting
lobe in addition to a sharp crossover between a compressible normal "strange
metal" state and a region characterized by a vanishing compressibility, which
marks the Mott insulator. Finally, we argue that the existence of robust
quantum numbers explains the stability against small perturbation of the system
and attributes to the topological "quantum protectorate" as observed in
strongly correlated systems.Comment: 23 pages, 12 figure
Connection between low energy effective Hamiltonians and energy level statistics
We study the level statistics of a non-integrable one dimensional interacting
fermionic system characterized by the GOE distribution. We calculate
numerically on a finite size system the level spacing distribution and
the Dyson-Mehta correlation. We observe that its low energy spectrum
follows rather the Poisson distribution, characteristic of an integrable
system, consistent with the fact that the low energy excitations of this system
are described by the Luttinger model. We propose this Random Matrix Theory
analysis as a probe for the existence and integrability of low energy effective
Hamiltonians for strongly correlated systems.Comment: REVTEX, 5 postscript figures at the end of the fil
The JCMT Gould Belt survey: Dense core clusters in Orion B
The James Clerk Maxwell Telescope Gould Belt Legacy Survey obtained SCUBA-2 observations of dense cores within three sub-regions of OrionB: LDN1622, NGC2023/2024, and NGC2068/2071, all of which contain clusters of cores. We present an analysis of the clustering properties of these cores, including the two-point correlation function and Cartwright’s Q parameter. We identify individual clusters of dense cores across all three regions using a minimal spanning tree technique, and find that in each cluster, the most massive cores tend to be centrally located. We also apply the independent M–Σ technique and find a strong correlation between core mass and the local surface density of cores. These two lines of evidence jointly suggest that some amount of mass segregation in clusters has happened already at the dense core stage
V371 Per - A Thick-Disk, Short-Period F/1O Cepheid
V371 Per was found to be a double-mode Cepheid with a fundamental mode period
of 1.738 days, the shortest among Galactic beat Cepheids, and an unusually high
period ratio of 0.731, while the other Galactic beat Cepheids have period
ratios between 0.697 and 0.713. The latter suggests that the star has a
metallicity [Fe/H] between -1 and -0.7. The derived distance from the Galactic
Plane places it in the Thick Disk or the Halo, while all other Galactic beat
Cepheids belong to the Thin Disk. There are indications from historical data
that both the fundamental and first overtone periods have lengthened.Comment: Accepted for publication in MNRA
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