1,868 research outputs found
Algunas observaciones sobre sa Font des Verger y su funcionamiento hidrolĂłgico
[spa] La presente comunicaciĂłn trata en lĂneas generales de la descripciĂłn y funcionamiento hĂdrico de "Sa Font des Verger". Estas observaciones constituyen los primeros datos para que en su dĂa pueda realizarse un trabajo más extenso, como contribuciĂłn al conocimiento de esta cavidad
Photon-mediated qubit interactions in one-dimensional discrete and continuous models
In this work we study numerically and analytically the interaction of two qubits in a one-dimensionalwaveguide, as mediated by the photons that propagate through the guide. We develop strategies to assert the Markovianity of the problem, the effective qubit-qubit interactions, and their individual and collective spontaneous emission. We prove the existence of collective Lamb shifts that affect the qubit-qubit interactions and the dependency of coherent and incoherent interactions on the qubit separation. We also develop the scattering theory associated with these models and prove single-photon spectroscopy does probe the renormalized resonances of the singleand multiqubit models, in sharp contrast to earlier toy models in which individual and collective Lamb shifts cancel
Microwave Photon Detector in Circuit QED
Quantum optical photodetection has occupied a central role in understanding
radiation-matter interactions. It has also contributed to the development of
atomic physics and quantum optics, including applications to metrology,
spectroscopy, and quantum information processing. The quantum microwave regime,
originally explored using cavities and atoms, is seeing a novel boost with the
generation of nonclassical propagating fields in circuit quantum
electrodynamics (QED). This promising field, involving potential developments
in quantum information with microwave photons, suffers from the absence of
photodetectors. Here, we design a metamaterial composed of discrete
superconducting elements that implements a high-efficiency microwave photon
detector. Our design consists of a microwave guide coupled to an array of
metastable quantum circuits, whose internal states are irreversibly changed due
to the absorption of photons. This proposal can be widely applied to different
physical systems and can be generalized to implement a microwave photon
counter.Comment: accepted in Phys. Rev. Let
Full two-photon downconversion of just a single photon
We demonstrate, both numerically and analytically, that it is possible to
generate two photons from one and only one photon. We characterize the output
two photon field and make our calculations close to reality by including
losses. Our proposal relies on real or artificial three-level atoms with a
cyclic transition strongly coupled to a one-dimensional waveguide. We show that
close to perfect downconversion with efficiency over 99% is reachable using
state-of-the-art Waveguide QED architectures such as photonic crystals or
superconducting circuits. In particular, we sketch an implementation in circuit
QED, where the three level atom is a transmon
On the shape of vortices for a rotating Bose Einstein condensate
For a Bose-Einstein condensate placed in a rotating trap, we study the
simplified energy of a vortex line derived in Aftalion-Riviere Phys. Rev. A 64,
043611 (2001) in order to determine the shape of the vortex line according to
the rotational velocity and the elongation of the condensate. The energy
reflects the competition between the length of the vortex which needs to be
minimized taking into account the anisotropy of the trap and the rotation term
which pushes the vortex along the z axis. We prove that if the condensate has
the shape of a pancake, the vortex stays straight along the z axis while in the
case of a cigar, the vortex is bent
Place branding as participatory governance? An interdisciplinary case study of Tasmania, Australia
Research in both public administration and place development has identified a need to develop more participatory approachesto governing cities and regions. Scholars have identified place branding as one of several potential policy instruments to enablemore participatory place development. Recently, academics working in diverse disciplines, including political studies, publicadministration, and regional development have suggested that an alternative, bottom-up, more participatory approach toplace branding could be employed. Such an interdisciplinary approach would use iterative communication exchanges withina network of diverse stakeholders including residents to better foster stakeholder participation, contribute to sustainabledevelopment, and deliver substantive social justice and increased citizen satisfaction. Building on this research and using anexploratory, qualitative, case-study methodology, our aim was to observe and analyze such interactions and communicativeexchanges in practice. Drawing on the experience of the Australian state of Tasmania, we studied stakeholder reactions tothe participatory place branding approach. We found that although participants were initially skeptical and identified manybarriers to implementing participatory place branding, they simultaneously became excited by its possibilities and able toidentify how many of the barriers could be transcended
Testing the Reliability of Financial Sustainability. The Case of Spanish Local Governments
Local Governments (LGs) have strengthened the financial control as a consequence of mandatory requirements to ensure financial sustainability in their management. The aim of this study is to determine whether financial indicators about financial conditions defined in Spanish regulation are backed by worldwide generally accepted financial benchmarking indicators. For this purpose, we analyze the relationship between Spanish indicators of financial sustainability based on European Union (EU) regulations and Financial Trends Monitoring System Indicators (FTMS) of the International City/County Management Association (ICMA). For this purpose, two methodologies are applied: discriminant analysis and logistic regression, where the dependent variables are each of the Spanish financial indicators and the independent variables are ICMA indicators. The evidence supports that variables that are related to the control of expenditures, debt and the revenues show a greater explanatory power of financial sustainability, being the most important elements which offer relevant information about the financial sustainability measurement of LGs
Structural instability of vortices in Bose-Einstein condensates
In this paper we study a gaseous Bose-Einstein condensate (BEC) and show
that: (i) A minimum value of the interaction is needed for the existence of
stable persistent currents. (ii) Vorticity is not a fundamental invariant of
the system, as there exists a conservative mechanism which can destroy a vortex
and change its sign. (iii) This mechanism is suppressed by strong interactions.Comment: 4 pages with 3 figures. Submitted to Phys. Rev. Let
Split Instability of a Vortex in an Attractive Bose-Einstein Condensate
An attractive Bose-Einstein condensate with a vortex splits into two pieces
via the quadrupole dynamical instability, which arises at a weaker strength of
interaction than the monopole and the dipole instabilities. The split pieces
subsequently unite to restore the original vortex or collapse.Comment: 4 pages, 4 figures, added figures and references, revised tex
Mesoscale simulations of polymer dynamics in microchannel flows
The non-equilibrium structural and dynamical properties of flexible polymers
confined in a square microchannel and exposed to a Poiseuille flow are
investigated by mesoscale simulations. The chain length and the flow strength
are systematically varied. Two transport regimes are identified, corresponding
to weak and strong confinement. For strong confinement, the transport
properties are independent of polymer length. The analysis of the long-time
tumbling dynamics of short polymers yields non-periodic motion with a sublinear
dependence on the flow strength. We find distinct differences for
conformational as well as dynamical properties from results obtained for simple
shear flow
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