Ultra Fast Nonlinear Optical Tuning of Photonic Crystal Cavities

We demonstrate fast (up to 20 GHz), low power (5 $\mu W$) modulation of photonic crystal (PC) cavities in GaAs containing InAs quantum dots. Rapid modulation through blue-shifting of the cavity resonance is achieved via free carrier injection by an above-band picosecond laser pulse. Slow tuning by several linewidths due to laser-induced heating is also demonstrated

Uniformly Rotating Homogeneous Rings in post-Newtonian Gravity

In this paper uniformly rotating relativistic rings are investigated analytically utilizing two different approximations simultaneously: (1) an expansion about the thin ring limit (the cross-section is small compared with the size of the whole ring) (2) post-Newtonian expansions. The analytic results for rings are compared with numerical solutions.Comment: 12 pages, 7 figures, v1: 2 tables added, agrees with published versio

The Parametric Transition of Strange Matter Rings to a Black Hole

It is shown numerically that strange matter rings permit a continuous transition to the extreme Kerr black hole. The multipoles as defined by Geroch and Hansen are studied and suggest a universal behaviour for bodies approaching the extreme Kerr solution parametrically. The appearance of a `throat region', a distinctive feature of the extreme Kerr spacetime, is observed. With regard to stability, we verify for a large class of rings, that a particle sitting on the surface of the ring never has enough energy to escape to infinity along a geodesic.Comment: 16 pages, 11 figures, v3: minor changes so as to coincide with published versio

Fast radio bursts: recent discoveries and future prospects

Fast radio bursts (FRBs) are quickly becoming a subject of intense interest in time-domain astronomy. The progenitors of FRBs remain unknown but a wide variety of models exist from cataclysmic to repeating scenarios. Advances in FRB detection using current and next-generation radio telescopes will enable the growth of the population in the next few years. Real-time discovery of FRBs is now possible with 6 sources detected in real-time within the past 2 years at the Parkes telescope. Here we discuss the developing strategies for maximising real-time science with FRBs including polarisation capture and multi-wavelength follow-up, with particular focus on real-time detections with the Parkes telescope as a test bed for fast radio burst science. We also discuss how our response to these events can pave the way for the next generation of FRB searches with wide-field interferometers.Comment: Published in Proceedings from 11th INTEGRAL Conference: Gamma-ray Astrophysics in Multi-Wavelenth Perspectiv

Fast Radio Bursts

The discovery of radio pulsars over a half century ago was a seminal moment in astronomy. It demonstrated the existence of neutron stars, gave a powerful observational tool to study them, and has allowed us to probe strong gravity, dense matter, and the interstellar medium. More recently, pulsar surveys have led to the serendipitous discovery of fast radio bursts (FRBs). While FRBs appear similar to the individual pulses from pulsars, their large dispersive delays suggest that they originate from far outside the Milky Way and hence are many orders-of-magnitude more luminous. While most FRBs appear to be one-off, perhaps cataclysmic events, two sources are now known to repeat and thus clearly have a longer-lived central engine. Beyond understanding how they are created, there is also the prospect of using FRBs -- as with pulsars -- to probe the extremes of the Universe as well as the otherwise invisible intervening medium. Such studies will be aided by the high implied all-sky event rate: there is a detectable FRB roughly once every minute occurring somewhere on the sky. The fact that less than a hundred FRB sources have been discovered in the last decade is largely due to the small fields-of-view of current radio telescopes. A new generation of wide-field instruments is now coming online, however, and these will be capable of detecting multiple FRBs per day. We are thus on the brink of further breakthroughs in the short-duration radio transient phase space, which will be critical for differentiating between the many proposed theories for the origin of FRBs. In this review, we give an observational and theoretical introduction at a level that is accessible to astronomers entering the field.Comment: Invited review article for The Astronomy and Astrophysics Revie

W mass and Triple Gauge Couplings at Tevatron

On behalf of CDF and D0 CollaborationsInternational audienceThe W mass is a crucial parameter in the Standard Model (SM) of particle physics, providing constraints on the mass of the Higgs boson as well as on new physics models via quantum loop corrections. On the other hand, any deviation of the triple gauge boson couplings (TGC) from their values predicted by the SM would be also an indication for new physics. We present recent measurements on W boson mass and searches for anomalous TGC (aTGC) in Wγ, Zγ, WW, WZ and ZZ at Fermilab Tevatron both by CDF and DØ Collaborations. The CDF Collaboration has measured the W boson mass using data corresponding to 2.2 fb−1 of integrated luminosity. The measurement, performed using electron and muon decays of W boson, yields a mass of MW = 80387 ± 19 MeV. The DØ Collaboration has measured MW = 80367 ± 26 MeV with data corresponding to 4.3 fb−1 of integrated luminosity in the channel W → ev. The combination with an earlier DØ result, using independant data sample at 1 fb−1 of integrated luminosity, yields MW = 80375 ± 23 MeV. The limits on anomalous TGCs parameters are consistent with the SM expectations