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

Ground state cooling of atoms in optical lattices

We propose two schemes for cooling bosonic and fermionic atoms that are trapped in a deep optical lattice. The first scheme is a quantum algorithm based on particle number filtering and state dependent lattice shifts. The second protocol alternates filtering with a redistribution of particles by means of quantum tunnelling. We provide a complete theoretical analysis of both schemes and characterize the cooling efficiency in terms of the entropy. Our schemes do not require addressing of single lattice sites and use a novel method, which is based on coherent laser control, to perform very fast filtering.Comment: 12 pages, 7 figure

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

Tratamiento quirúrgico percutáneo del hallux valgus mediante osteotomías múltiples

Objetivo: Se presenta la experiencia del tratamiento del hallux valgus mediante la realización de osteotomía distal del primer metatarsiano y osteotomía de la falange con liberación del abductor por técnicas percutáneas. Material y método: Desde junio de 1996 hasta junio de 1997 han sido intervenidos 64 pacientes, la mayor parte mujeres con hallux valgus de grado moderado con un ángulo intermetatarsiano medio de 14.5° y un ángulo del complejo articular proximal (PASA) de 17,7° de media. Resultados: Los resultados obtenidos desde el punto de vista radiológico pusieron de manifiesto una corrección media de 5° del ángulo intermetatarsal y se obtiene un valor medio del PASA de 8,2°. La consolidación de las osteotomías se consiguió en el 100% de los pies sin retardos de consolidación significativos, salvo en un caso que precisó más de tres meses. Por lo que se refiere a las complicaciones, al no utilizar ningún medio de fijación, el desplazamiento de las osteotomías fue muy frecuente, pero sólo en un 8% de la serie tuvieron repercusión clínica. El acortamiento del primer metarsiano fue la norma alcanzando como media 0,7 cm, lo que se intentó compensar con un descenso de la cabeza del primer metatarsiano; la metatarsalgia por trasferencia en esta serie ocurrió en el 25% de los casos. No se presentaron alteraciones neurológicas, infección ni síndromes flebíticos postquiriírgicos. Conclusión: Parece que la técnica de Reverdin-Isham, por vía percutánea, es un buen método para el tratamiento del hallux valgus. ya que proporciona unos resultados clínicos muy aceptables, sin presentar complicaciones importantes; en el momento actual hay que asociar con mucha más frecuencia la realineación metatarsal a la cirugía del hallux valgus para evitar las metatarsalgias por trasferencia

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

Inducing nonclassical lasing via periodic drivings in circuit quantum electrodynamics

We show how a pair of superconducting qubits coupled to a microwave cavity mode can be used to engineer a single-atom laser that emits light into a nonclassical state. Our scheme relies on the dressing of the qubit-field coupling by periodic modulations of the qubit energy. In the dressed basis, the radiative decay of the first qubit becomes an effective incoherent pumping mechanism that injects energy into the system, hence turning dissipation to our advantage. A second, auxiliary qubit is used to shape the decay within the cavity, in such a way that lasing occurs in a squeezed basis of the cavity mode. We characterize the system both by mean-field theory and exact calculations. Our work may find applications in the generation of squeezing and entanglement in circuit QED, as well as in the study of dissipative few- and many-body phase transitions

Scalable Ion Trap Quantum Computing without Moving Ions

A hybrid quantum computing scheme is studied where the hybrid qubit is made of an ion trap qubit serving as the information storage and a solid-state charge qubit serving as the quantum processor, connected by a superconducting cavity. In this paper, we extend our previous work [1] and study the decoherence, coupling and scalability of the hybrid system. We present our calculations of the decoherence of the coupled ion - charge system due to the charge fluctuations in the solid-state system and the dissipation of the superconducting cavity under laser radiation. A gate scheme that exploits rapid state flips of the charge qubit to reduce decoherence by the charge noise is designed. We also study a superconducting switch that is inserted between the cavity and the charge qubit and provides tunable coupling between the qubits. The scalability of the hybrid scheme is discussed together with several potential experimental obstacles in realizing this scheme

Stable and unstable vortices in multicomponent Bose-Einstein condensates

We study the stability and dynamics of vortices in two-species condensates as prepared in the recent JILA experiment (M. R. Andrews {\em et al.}, Phys. Rev. Lett. 83 (1999) 2498). We find that of the two available configurations, in which one specie has vorticity $m=1$ and the other one has $m=0$, only one is linearly stable, which agrees with the experimental results. However, it is found that in the unstable case the vortex is not destroyed by the instability, but may be transfered from one specie to the other or display complex spatiotemporal dynamics.Comment: 4 EPS figures, now features a three-dimensional stud

The Bose–Hubbard model with squeezed dissipation

The stationary properties of the Bose–Hubbard model under squeezed dissipation are investigated. The dissipative model does not possess aU (1) symmetry but conserves parity. We find that 〈a j 〉 = 0 always holds, so no symmetry breaking occurs. Without the onsite repulsion, the linear case is known to be critical. At the critical point the system freezes to an EPR state with infinite two mode entanglement. We show here that the correlations are rapidly destroyed whenever the repulsion is switched on. As we increase the latter, the system approaches a thermal state with an effective temperature defined in terms of the squeezing parameter in the dissipators. We characterize this transition by means of a Gutzwiller ansatz and the Gaussian Hartree–Fock–Bogoliubov approximation

Coherent control of trapped ions using off-resonant lasers

In this paper we develop a unified framework to study the coherent control of trapped ions subject to state-dependent forces. Taking different limits in our theory, we can reproduce two different designs of a two-qubit quantum gate --the pushing gate [1] and the fast gates based on laser pulses from Ref. [2]--, and propose a new design based on continuous laser beams. We demonstrate how to simulate Ising Hamiltonians in a many ions setup, and how to create highly entangled states and induce squeezing. Finally, in a detailed analysis we identify the physical limits of this technique and study the dependence of errors on the temperature. [1] J.I. Cirac, P. Zoller, Nature, 404, 579, 2000. [2] J.J. Garcia-Ripoll, P. Zoller, J.I. Cirac, PRL 67, 062318, 200