Exact constraints on D≤10\leq 10 Myers Perry black holes and the Wald Problem

Exact relations on the existence of event horizons of Myers Perry black holes are obtained in $D\leq 10$ dimensions. It is further shown that naked singularities can not be produced by "spinning-up" these black holes by shooting particles into their $\lfloor\frac{D-1}{2}\rfloor$ equatorial planes.Comment: 7 pages, 11 figures, version two corrects an earlier error in equation (35) and adds some plots for cohomogeneity-2 and 3 black hole

Localized detection of quantum entanglement through the event horizon

We present a completely localized solution to the problem of entanglement degradation in non-inertial frames. A two mode squeezed state is considered from the viewpoint of two observers, Alice (inertial) and Rob (accelerated), and a model of localized projective detection is used to study the amount of entanglement that they are able to extract from the initial state. The Unruh vacuum noise plays only a minor role in the degradation process. The dominant source of degradation is a mode mismatch between the mode of the squeezed state Rob observes and the mode he is able to detect from his accelerated frame. Leakage of the initial mode through Rob's horizon places a limit on his ability to fully measure the state, leading to an inevitable degradation of entanglement that even in principle cannot be corrected by changing the hardware design of his detector.Comment: 5 pages, 3 figure

Superconducting circuit boundary conditions beyond the Dynamical Casimir Effect

We study analytically the time-dependent boundary conditions of superconducting microwave circuit experiments in the high plasma frequency limit, in which the conditions are Robin-type and relate the value of the field to the spatial derivative of the field. We give an explicit solution to the field evolution for boundary condition modulations that are small in magnitude but may have arbitrary time dependence, in a formalism that applies both to a semiopen waveguide and to a closed waveguide with two independently adjustable boundaries. The correspondence between the microwave Robin boundary conditions and the mechanically-moving Dirichlet boundary conditions of the Dynamical Casimir Effect is shown to break down at high field frequencies, approximately one order of magnitude above the frequencies probed in the 2011 experiment of Wilson et al. Our results bound the parameter regime in which a microwave circuit can be used to model relativistic effects in a mechanically-moving cavity, and they show that beyond this parameter regime moving mirrors produce more particles and generate more entanglement than their non-moving microwave waveguide simulations.Comment: 29 pages, 2 figures. v3: minor updates, including a change in the title. Published versio

Entanglement of two qubits in a relativistic orbit

The creation and destruction of entanglement between a pair of interacting two-level detectors accelerating about diametrically opposite points of a circular path is investigated. It is found that any non-zero acceleration has the effect of suppressing the vacuum entanglement and enhancing the acceleration radiation thereby reducing the entangling capacity of the detectors. Given that for large accelerations the acceleration radiation is the dominant effect, we investigate the evolution of a two detector system initially prepared in a Bell state using a perturbative mater equation and treating the vacuum fluctuations as an unobserved environment. A general function for the concurrence is obtained for stationary and symmetric worldlines in flatspace. The entanglement sudden death time is computed.Comment: v2: Some typo's fixed, figures compressed to smaller filesize and added some references

Ruling out stray thermal radiation in analogue black holes

Experimental searches for the thermal radiation from analogue black holes require the measurement of very low temperatures in regimes where other thermal noises may interfere or even mimic the sought-after effect. In this letter, we parameterize the family of bosonic thermal channels which give rise to such thermal effects and show that by use of coherent states and homodyne detection one can rule out the non-Hawking contributions and identify those candidate sources which arise from Hawking-like processes.Comment: 5 pages, 2 figure

Family Control and Financing Decisions

Empirical studies examining the financing decisions of the firm focus exclusively on publicly held firms, not family-controlled firms despite their economic importance. This study investigates the external financing behavior of family-controlled firms, using a comprehensive sample of 777 large European firms during the period 1998 to 2008. We document that, unlike nonfamily-controlled firms, the external financing decisions of family-controlled firms are influenced by control incentives and information asymmetry considerations. We find that family firms have a strong preference for debt financing, a noncontrol diluting security, while they are more reluctant to raise capital through equity offerings in comparison to nonfamily firms. We also find that credit markets, view family firms as more risk-averse and that family firms invest more in low-risk (fixed-asset capital expenditures (CAPEX)), than in high-risk investments (R&D expenditures) confirming their non-risk seeking behavior.Family firms, financing decisions, equity issues, debt issues, capital structure.

Split fermion quasi-normal modes

In this paper we use the conformal properties of the spinor field to show how we can obtain the fermion quasi-normal modes for a higher dimensional Schwarzschild black hole. These modes are of interest in so called split fermion models, where quarks and leptons are required to exist on different branes in order to keep the proton stable. As has been previously shown, for brane localized fields, the larger the number of dimensions the faster the black hole damping rate. Moreover, we also present the analytic forms of the quasi-normal frequencies in both the large angular momentum and the large mode number limits.Comment: 11 pages, 7 figures, version 2 added reference

Black hole quasinormal modes using the asymptotic iteration method

In this article we show that the asymptotic iteration method (AIM) allows one to numerically find the quasinormal modes of Schwarzschild and Schwarzschild de Sitter (SdS) black holes. An added benefit of the method is that it can also be used to calculate the Schwarzschild anti-de Sitter (SAdS) quasinormal modes for the case of spin zero perturbations. We also discuss an improved version of the AIM, more suitable for numerical implementation.Comment: 10 pages, LaTeX; references added; substantially expanded versio