Conclusive and arbitrarily perfect quantum state transfer using parallel spin chain channels

We suggest a protocol for perfect quantum communication through spin chain channels. By combining a dual-rail encoding with measurements only at the receiving end, we can get conclusively perfect state transfer, whose probability of success can be made arbitrarily close to unity. As an example of such an amplitude delaying channel, we show how two parallel Heisenberg spin chains can be used as quantum wires. Perfect state transfer with a probability of failure lower than P in a Heisenberg chain of N spin-1/2 particles can be achieved in a timescale of the order of N^1.7|ln(P)|. We demonstrate that our scheme is more robust to decoherence and non-optimal timing than any scheme using single spin chains.Comment: 6 pages, 4 figures ; expanded version inluding discussion of transmission tim

Measured reduction in Alfv\'en wave energy propagating through longitudinal gradients scaled to match solar coronal holes

We have explored the effectiveness of a longitudinal gradient in Alfv\'en speed in reducing the energy of propagating Alfv\'en waves under conditions scaled to match solar coronal holes. The experiments were conducted in the Large Plasma Device at the University of California, Los Angeles. Our results show that the energy of the transmitted Alfv\'en wave decreases as the inhomogeneity parameter, $\lambda/L_{\rm A}$, increases. Here, $\lambda$ is the wavelength of the Alfv\'en wave and $L_{\rm A}$ is the scale length of Alfv\'en speed gradient. For gradients similar to those in coronal holes, the waves are observed to lose a factor of $\approx 5$ more energy than they do when propagating through a uniform plasma without a gradient. We have carried out further experiments and analyses to constrain the cause of wave energy reduction in the gradient. The loss of Alfv\'en wave energy from mode coupling is unlikely, as we have not detected any other modes. Contrary to theoretical expectations, the reduction in the energy of the transmitted wave is not accompanied by a detectable reflected wave. Nonlinear effects are ruled out as the amplitude of the initial wave is too small and the wave frequency well below the ion cyclotron frequency. Since the total energy must be conserved, it is possible that the lost wave energy is being deposited in the plasma. Further studies are needed to explore where the energy is going

Quantum communication via a continuously monitored dual spin chain

We analyze a recent protocol for the transmission of quantum states via a dual spin chain [Burgarth and Bose, Phys. Rev. A 71, 052315 (2005)] under the constraint that the receiver's measurement strength is finite. That is, we consider the channel where the ideal, instantaneous and complete von Neumann measurements are replaced with a more realistic continuous measurement. We show that for optimal performance the measurement strength must be "tuned" to the channel spin-spin coupling, and once this is done, one is able to achieve a similar transmission rate to that obtained with ideal measurements. The spin chain protocol thus remains effective under measurement constraints.Comment: 5 pages, revtex 4, 3 eps figure

Revealing the galaxy-halo connection in IllustrisTNG

We use the IllustrisTNG (TNG) simulations to explore the galaxy-halo connection as inferred from state-of-the-art cosmological, magnetohydrodynamical simulations. With the high mass resolution and large volume achieved by combining the 100 Mpc (TNG100) and 300 Mpc (TNG300) volumes, we establish the mean occupancy of central and satellite galaxies and their dependence on the properties of the dark matter haloes hosting them. We derive best-fitting HOD parameters from TNG100 and TNG300 for target galaxy number densities of $\bar{n}_g = 0.032\,h^3$Mpc$^{-3}$ and $\bar{n}_g = 0.016\,h^3$Mpc$^{-3}$, respectively, corresponding to a minimum galaxy stellar mass of $M_\star\sim1.9\times10^9\,{\rm M}_\odot$ and $M_\star\sim3.5\times10^9\,{\rm M}_\odot$, respectively, in hosts more massive than $10^{11}\,{\rm M}_\odot$. Consistent with previous work, we find that haloes located in dense environments, with low concentrations, later formation times, and high angular momenta are richest in their satellite population. At low mass, highly-concentrated haloes and those located in overdense regions are more likely to contain a central galaxy. The degree of environmental dependence is sensitive to the definition adopted for the physical boundary of the host halo. We examine the extent to which correlations between galaxy occupancy and halo properties are independent and demonstrate that HODs predicted by halo mass and present-day concentration capture the qualitative dependence on the remaining halo properties. At fixed halo mass, concentration is a strong predictor of the stellar mass of the central galaxy, which may play a defining role in the fate of the satellite population. The radial distribution of satellite galaxies, which exhibits a universal form across a wide range of host halo mass, is described accurately by the best-fit NFW density profile of their host haloes.Comment: 20 pages, 13 figures, 1 table, comments welcom

Transfer of a Polaritonic Qubit through a Coupled Cavity Array

We demonstrate a scheme for quantum communication between the ends of an array of coupled cavities. Each cavity is doped with a single two level system (atoms or quantum dots) and the detuning of the atomic level spacing and photonic frequency is appropriately tuned to achieve photon blockade in the array. We show that in such a regime, the array can simulate a dual rail quantum state transfer protocol where the arrival of quantum information at the receiving cavity is heralded through a fluorescence measurement. Communication is also possible between any pair of cavities of a network of connected cavities.Comment: Contribution to Special Issue in Journal of Modern Optics celebrating the 60th birthday of Peter L. Knigh

Use of Micellar Liquid Chromatography to Determine Mebendazole in Dairy Products and Breeding Waste from Bovine Animals

Mebendazole is an anthelmintic drug used in cattle production. However, residues may occur in produced food and in excretions, jeopardizing population health. A method based on micellar liquid chromatography (MLC) was developed to determine mebendazole in dairy products (milk, cheese, butter, and curd) and nitrogenous waste (urine and dung) from bovine animals. Sample treatment was expedited to simple dilution or solid-to-liquid extraction, followed by filtration and direct injection of the obtained solution. The analyte was resolved from matrix compounds in less than 8 min, using a C18 column and a mobile phase made up of 0.15 M sodium dodecyl sulfate (SDS)–6% 1-pentanol phosphate buffered at pH 7, and running at 1 mL/min under isocratic mode. Detection was performed by absorbance at 292 nm. The procedure was validated according to the guidelines of the EU Commission Decision 2002/657/EC in terms of: specificity, method calibration range (from the limit of quantification to 25–50 ppm), sensitivity (limit of detection 0.1–0.2 ppm; limit of quantification, 0.3–0.6 ppm), trueness (92.5–102.3%), precision (<7.5%, expressed at RSD), robustness, and stability. The method is reliable, sensitive, easy-to-handle, eco-friendly, safe, inexpensive, and provides a high sample-throughput. Therefore, it is useful for routine analysis as a screening or quantification method in a laboratory for drug-residue control

Uptake, depuration, and behavioural effects of oxazepam on activity and foraging in a tropical snail (Melanoides tuberculata)

Pharmaceuticals are increasingly being detected in surface waters around the globe, giving rise to concerns that they may alter the physiology and behaviour of aquatic organisms exposed in the wild. Invertebrates represent important components of many ecosystems and bear a high potential for transmitting pharmaceutical contaminants to higher trophic levels. Here, we present a laboratory study in which we exposed a freshwater tropical snail, Melanoides tuberculata, to a serial dilution of the benzodiazepine oxazepam ranging from 50 ng/L to 5 mg/L. We tested for subsequent behavioural effects, including locomotor activity and foraging propensity, at two diurnal time points (day and night), and across three days. We found that the snails displayed a high level of behavioural tolerance to all treatments of oxazepam except at the highest exposure, where locomotor and foraging activity declined. We also detected a weak non-monotonic response curve suggestive of behavioural disinhibition at moderate exposure levels. Regardless of treatment, the snails were also less active after three days of exposure and more active during nighttime observations. We measured the uptake of oxazepam in tissues across treatments, showing that it bioconcentrated at up to 29 times the water exposure level (BCF range: 7 - 29). Finally, we characterized the uptake/depuration pharmacokinetics of oxazepam in snail tissues across time, which revealed that the snails reach a steady state equilibrium i

Local controllability of quantum networks

We give a sufficient criterion that guarantees that a many-body quantum system can be controlled by properly manipulating the (local) Hamiltonian of one of its subsystems. The method can be applied to a wide range of systems: it does not depend on the details of the couplings but only on their associated topology. As a special case, we prove that Heisenberg and Affleck-Kennedy-Lieb-Tasaki chains can be controlled by operating on one of the spins at their ends. In principle, arbitrary quantum algorithms can be performed on such chains by acting on a single qubit.Comment: 4 pages, 3 figure