Universality of Entanglement Transitions from Stroboscopic to Continuous Measurements.

Measurement-driven transitions between extensive and subextensive scaling of the entanglement entropy receive interest as they illuminate the intricate physics of thermalization and control in open interacting quantum systems. While this transition is well established for stroboscopic measurements in random quantum circuits, a crucial link to physical settings is its extension to continuous observations, where for an integrable model it has been shown that the transition changes its nature and becomes immediate. Here, we demonstrate that the entanglement transition at finite coupling persists if the continuously measured system is randomly nonintegrable, and show that it is smoothly connected to the transition in the stroboscopic models. This provides a bridge between a wide range of experimental settings and the wealth of knowledge accumulated for the latter systems.

Exciton Polaritons in a Two-Dimensional Lieb Lattice with Spin-Orbit Coupling.

We study exciton polaritons in a two-dimensional Lieb lattice of micropillars. The energy spectrum of the system features two flat bands formed from S and P_{x,y} photonic orbitals, into which we trigger bosonic condensation under high power excitation. The symmetry of the orbital wave functions combined with photonic spin-orbit coupling gives rise to emission patterns with pseudospin texture in the flat band condensates. Our Letter shows the potential of polariton lattices for emulating flat band Hamiltonians with spin-orbit coupling, orbital degrees of freedom, and interactions.

Effect of chiral symmetry on chaotic scattering from Majorana zero modes.

In many of the experimental systems that may host Majorana zero modes, a so-called chiral symmetry exists that protects overlapping zero modes from splitting up. This symmetry is operative in a superconducting nanowire that is narrower than the spin-orbit scattering length, and at the Dirac point of a superconductor-topological insulator heterostructure. Here we show that chiral symmetry strongly modifies the dynamical and spectral properties of a chaotic scatterer, even if it binds only a single zero mode. These properties are quantified by the Wigner-Smith time-delay matrix Q=-iℏS^{†}dS/dE, the Hermitian energy derivative of the scattering matrix, related to the density of states by ρ=(2πℏ)^{-1}TrQ. We compute the probability distribution of Q and ρ, dependent on the number ν of Majorana zero modes, in the chiral ensembles of random-matrix theory. Chiral symmetry is essential for a significant ν dependence.

Fermion-parity anomaly of the critical supercurrent in the quantum spin-Hall effect.

The helical edge state of a quantum spin-Hall insulator can carry a supercurrent in equilibrium between two superconducting electrodes (separation L, coherence length ξ). We calculate the maximum (critical) current I(c) that can flow without dissipation along a single edge, going beyond the short-junction restriction L << ξ of earlier work, and find a dependence on the fermion parity of the ground state when L becomes larger than ξ. Fermion-parity conservation doubles the critical current in the low-temperature, long-junction limit, while for a short junction I(c) is the same with or without parity constraints. This provides a phase-insensitive, dc signature of the 4 π-periodic Josephson effect.

Long-time signatures of short-time dynamics in decaying quantum-chaotic systems.

We analyze the decay of classically chaotic quantum systems in the presence of fast ballistic escape routes on the Ehrenfest time scale. For a continuous excitation process, the form factor of the decay cross section deviates from the universal random-matrix result on the Heisenberg time scale, i.e., for times much larger than the time for ballistic escape. We derive an exact analytical description and compare our results with numerical simulations for a dynamical model.

Hepatic encephalopathy in liver cirrhosis: pathogenesis, diagnosis and management.

The pathogenesis of hepatic encephalopathy (HE) is unknown. Many theories have been proposed. Most established therapies are based on such theories but since no theory has have ever been proved, therapies have to be considered empiric. The spectrum of HE ranges from minimal cerebral functional deficits, which can only be found by sensitive psychometric tests, to coma with signs of decerebration. HE has arbitrarily been divided into stages. A number of precipitating factors are known and the first line of therapy should always be the elimination of these factors. The differential diagnosis includes all states of impaired consciousness and deficits in cerebral function in patients with chronic liver disease, and clinical and biochemical tests to differentiate are indicated. The therapeutic options for HE include: protein restriction only for a limited time in comatous patients; nonabsorbable antibiotics (aminoglycosides), which because of adverse effects are also limited to higher grades of HE: intestinal cleansing which is applicable in all degrees of HE; lactulose, branched chain aminoacids and ornithin aspartate which have been proven to be effective and can be applied long term in patients with lower grades of HE.

Search for two-scale localization in disordered wires in a magnetic field

A recent paper [A. V. Kolesnikov and K. B. Efetov, Phys. Rev. Lett. 83, 3689 (1999)] predicts a two-scale behavior of wave function decay in disordered wires in the crossover regime from preserved to broken time-reversal symmetry. We have tested this prediction by a transmission approach, relying on the Borland conjecture that relates the decay length of the transmittance to the decay length of the wave functions. Our numerical simulations show no indication of two-scale behavior.

Transmission delay times of localized waves.

We investigate the effects of wave localization on the delay time tau (frequency sensitivity of the scattering phase shift) of a wave transmitted through a disordered waveguide. Localization results in a separation tau=chi+chi(') of the delay time into two independent but equivalent contributions, associated to the left and right end of the waveguide. For N=1 propagating modes, chi and chi(') are identical to half the reflection delay time of each end of the waveguide. In this case the distribution function P(tau) in an ensemble of random disorder can be obtained analytically. For N>1 propagating modes the distribution function can be approximated by a simple heuristic modification of the single-channel problem. We find a strong correlation between channels with long reflection delay times and the dominant transmission channel.

Statistics of finite-time Lyapunov exponents in a random time-dependent potential.

The sensitivity of trajectories over finite-time intervals t to perturbations of the initial conditions can be associated with a finite-time Lyapunov exponent lambda, obtained from the elements M(ij) of the stability matrix M. For globally chaotic dynamics, lambda tends to a unique value (the usual Lyapunov exponent lambda(infinity)) for almost all trajectories as t is sent to infinity, but for finite t it depends on the initial conditions of the trajectory and can be considered as a statistical quantity. We compute for a particle moving in a randomly time-dependent, one-dimensional potential how the distribution function P(lambda;t) approaches the limiting distribution P(lambda; infinity)=delta(lambda-lambda(infinity)). Our method also applies to the tail of the distribution, which determines the growth rates of moments of M(ij). The results are also applicable to the problem of wave-function localization in a disordered one-dimensional potential.

Semiclassical singularities from bifurcating orbits.

We investigated numerically, for a generic quantum system (a kicked top), how the singular behavior of classical systems at bifurcations is reflected by their quantum counterpart. Good agreement is found with semiclassical predictions.

Localization-induced coherent backscattering effect in wave dynamics.

We investigate the statistics of single-mode delay times of waves reflected from a disordered waveguide in the presence of wave localization. The distribution of delay times is qualitatively different from the distribution in the diffusive regime, and sensitive to coherent backscattering: The probability of finding small delay times is enhanced by a factor close to sqrt[2] for reflection angles near the angle of incidence. This dynamic effect of coherent backscattering disappears in the diffusive regime.

Measurements of local PO2 in the resting skeletal muscles of rats with portocaval anastomosis (PCA) under normoxic conditions.

Direct measurements of local oxygen pressure by means of platinum multiwire electrode were performed in rats to investigate the effect of an end-to-side portocaval shunt procedure on muscle tissue oxygenation. Compared with intact rats and/or sham operated animals, rats with portocaval anastomosis showed a significant increase of muscle tissue oxygenation with nearly bellshaped pO2 histograms. This considerable increase in tissue oxygenation might appear to be due to the well known PCA induced hyperdynamic cardiovascular state.

Evaluation of the Crohn's Disease Activity Index (CDAI) and the Dutch Index for severity and activity of Crohn's disease. An analysis of the data from the European Cooperative Crohn's Disease Study.

In the European Cooperative Crohn's Disease Study a general documentation of clinical and laboratory data was made at the entry into the study in 452 patients. These patients were in different states of their disease from quiescent to very active. In all patients the Crohn's Disease Activity Index of Best (CDAI) and the Dutch Index of van Hees was calculated. Three gastroenterologists did a global clinical rating and a separate laboratory rating without knowledge of the indices. The ratings were then correlated with the indices in the individual patients. The clinical rating correlated well with the CDAI (r = 0.88) and less with the Dutch Index (r = 0.672). On the other hand the laboratory rating showed a better correlation with the Dutch Index (r = 0.742) than with the CDAI (r = 0.573). This demonstrates that the CDAI preferably is an estimate of the clinical severity of the disease and not of the activity of inflammation. Vice versa the Dutch Index is mainly reflecting the activity of the inflammatory process.