Interpretation of experimental results on Kondo systems with crystal field

We present a simple approach to calculate the thermodynamic properties of single Kondo impurities including orbital degeneracy and crystal field effects (CFE) by extending a previous proposal by K. D. Schotte and U. Schotte [Physics Lett. A 55, 38 (1975)]. Comparison with exact solutions for the specific heat of a quartet ground state split into two doublets shows deviations below $10\%$ in absence of CFE and a quantitative agreement for moderate or large CFE. As an application, we fit the measured specific heat of the compounds CeCu$_2$Ge$_2$, CePd$_{3}$Si$_{0.3}$, CePdAl, CePt, Yb$_2$Pd$_2$Sn and YbCo$_2$Zn$_{20}$. The agreement between theory and experiment is very good or excellent depending on the compound, except at very low temperatures due to the presence of magnetic correlations (not accounted in the model)

Extreme intranight variability in the BL Lacertae object AO 0235+164

We present results of two-colour photometry with high time resolution of the violently variable BL Lac object AO 0235+164. We have found extreme intranight variability with amplitudes of ~ 100 % over time scales of 24 hours. Changes of 0.5 magnitudes in both R and V bands were measured within a single night, and variations up to 1.2 magnitudes occurred from night to night. A complete outburst with an amplitude ~ 30 % was observed during one of the nights, while the spectrum remained unchanged. This seems to support an origin based on a thin relativistic shock propagating in such a way that it changes the viewing angle, as recently suggested by Kraus et al. (1999) and Qian et al. (2000).Comment: 4 pages, 3 figures, to appear in Astronomy & Astrophysics (Letters

Probing magnetic order in ultracold lattice gases

A forthcoming challenge in ultracold lattice gases is the simulation of quantum magnetism. That involves both the preparation of the lattice atomic gas in the desired spin state and the probing of the state. Here we demonstrate how a probing scheme based on atom-light interfaces gives access to the order parameters of nontrivial quantum magnetic phases, allowing us to characterize univocally strongly correlated magnetic systems produced in ultracold gases. This method, which is also nondemolishing, yields spatially resolved spin correlations and can be applied to bosons or fermions. As a proof of principle, we apply this method to detect the complete phase diagram displayed by a chain of (rotationally invariant) spin-1 bosons.Comment: published versio

Communicating via ignorance: Increasing communication capacity via superposition of order

Classically, no information can be transmitted through a depolarising, that is a completely noisy, channel. We show that by combining a depolarising channel with another channel in an indefinite causal order---that is, when there is superposition of the order that these two channels were applied---it becomes possible to transmit significant information. We consider two limiting cases. When both channels are fully-depolarising, the ideal limit is communication of 0.049 bits; experimentally we achieve $(3.4{\pm}0.2){\times}10^{-2}$ bits. When one channel is fully-depolarising, and the other is a known unitary, the ideal limit is communication of 1 bit. We experimentally achieve 0.64${\pm}$0.02 bits. Our results offer intriguing possibilities for future communication strategies beyond conventional quantum Shannon theory

Models for gamma-ray production in low-mass microquasars

Unlike high-mass gamma-ray binaries, low-mass microquasars lack external sources of radiation and matter that could produce high-energy emission through interactions with relativistic particles. In this work we consider the synchrotron emission of protons and leptons that populate the jet of a low-mass microquasar. In our model photohadronic and inverse Compton (IC) interactions with synchrotron photons produced by both protons and leptons result in a high-energy tail of the spectrum. We also estimate the contribution from secondary pairs injected through photopair production. The high-energy emission is dominated by radiation of hadronic origin, so we can call these objects proton microquasars.Comment: 4 pages, 2 figures, accepted for publication in the International Journal of Modern Physics D, proceedings of HEPRO meeting, held in Dublin, in September 200

Behaviour of compacted silt used to construct flood embankment

This paper investigates the unsaturated mechanical behaviour of a fill material sampled from flood embankments located along the Bengawan Solo River in Indonesia. In order to gain a better understanding of this fill material, in situ tests were carried out alongside an extensive laboratory programme. Two different phenomena related to changes in moisture content of the embankment fill material are experimentally studied herein: (a) volumetric collapse and (b) variation in shear strength with suction. At low densities, similar to those found in situ, the material exhibited significant volumetric collapse behaviour. Triaxial tests carried out under saturated, suction-controlled and constant water content conditions indicate that the shear strength of the material increased with suction; in particular the effective angle of friction increased from 24.9 degrees under saturated conditions to 35.8 degrees under air-dried conditions

Hiding Ignorance Using High Dimensions

The absence of information -- entirely or partly -- is called ignorance. Naturally, one might ask if some ignorance of a whole system will imply some ignorance of its parts. Our classical intuition tells us yes, however quantum theory tells us no: it is possible to encode information in a quantum system so that despite some ignorance of the whole, it is impossible to identify the unknown part arXiv:1011.6448. Experimentally verifying this counter-intuitive fact requires controlling and measuring quantum systems of high dimension $(d {>} 9)$. We provide this experimental evidence using the transverse spatial modes of light, a powerful resource for testing high dimensional quantum phenomenon