Observation of many-body localization of interacting fermions in a quasi-random optical lattice

We experimentally observe many-body localization of interacting fermions in a one-dimensional quasi-random optical lattice. We identify the many-body localization transition through the relaxation dynamics of an initially-prepared charge density wave. For sufficiently weak disorder the time evolution appears ergodic and thermalizing, erasing all remnants of the initial order. In contrast, above a critical disorder strength a significant portion of the initial ordering persists, thereby serving as an effective order parameter for localization. The stationary density wave order and the critical disorder value show a distinctive dependence on the interaction strength, in agreement with numerical simulations. We connect this dependence to the ubiquitous logarithmic growth of entanglement entropy characterizing the generic many-body localized phase.Comment: 6 pages, 6 figures + supplementary informatio

Lower plate structure and upper plate deformational segmentation at the Sunda-Banda arc transition, Indonesia

The Sunda‐Banda arc transition at the eastern termination of the Sunda margin (Indonesia) represents a unique natural laboratory to study the effects of lower plate variability on upper plate deformational segmentation. Neighboring margin segments display a high degree of structural diversity of the incoming plate (transition from an oceanic to a continental lower plate, presence/absence of an oceanic plateau, variability of subducting seafloor morphology) as well as a wide range of corresponding fore‐arc structures, including a large sedimentary basin and an accretionary prism/outer arc high of variable size and shape. Here, we present results of a combined analysis of seismic wide‐angle refraction, multichannel streamer and gravity data recorded in two trench normal corridors located offshore the islands of Lombok (116°E) and Sumba (119°E). On the incoming plate, the results reveal a 8.6–9.0 km thick oceanic crust, which is progressively faulted and altered when approaching the trench, where upper mantle velocities are reduced to ∼7.5 km/s. The outer arc high, located between the trench and the fore‐arc basin, is characterized by sedimentary‐type velocities (Vp < 5.5 km/s) down to the top of the subducting slab (∼13 km depth). The oceanic slab can be traced over 70–100 km distance beneath the fore arc. A shallow serpentinized mantle wedge at ∼16 km depth offshore Lombok is absent offshore Sumba, where our models reveal the transition to the collisional regime farther to the east and to the Sumba block in the north. Our results allow a detailed view into the complex structure of both the deeper and shallower portions of the eastern Sunda margin

Sport, War and Democracy in Classical Athens

This article concerns the paradox of athletics in classical Athens. Democracy may have opened up politics to every class of Athenian but it had little impact on sporting participation. The city’s athletes continued to drawn predominantly from the upper class. It comes as a surprise then that lower-class Athenians actually esteemed athletes above every other group in the public eye, honoured them very generously when they won, and directed a great deal of public and private money to sporting competitions and facilities. In addition athletics escaped the otherwise persistent criticism of upper-class activities in the popular culture of the democracy. The research of social scientists on sport and aggression suggests this paradox may have been due to the cultural overlap between athletics and war under the Athenian democracy. The article concludes that the practical and ideological democratization of war by classical Athens legitimized and supported upper-class sport

Socioeconomic status and health in the second half of life: findings from the German Ageing Survey

This study examined social inequalities in health in the second half of life. Data for empirical analyses came from the second wave of the German Ageing Survey (DEAS), an ongoing population-based, representative study of community dwelling persons living in Germany, aged 40–85 years (N = 2,787). Three different indicators for socioeconomic status (SES; education, income, financial assets as an indicator for wealth) and health (physical, functional and subjective health) were employed. It could be shown that SES was related to health in the second half of life: Less advantaged persons between 40 and 85 years of age had worse health than more advantaged persons. Age gradients varied between status indicators and health dimensions, but in general social inequalities in health were rather stable or increasing over age. The latter was observed for wealth-related absolute inequalities in physical and functional health. Only income-related differences in subjective health decreased at higher ages. The amount of social inequality in health as well as its development over age did not vary by gender and place of residence (East or West Germany). These results suggest that, in Germany, the influence of SES on health remains important throughout the second half of life

Periodically driving a many-body localized quantum system

We experimentally study a periodically driven many-body localized system realized by interacting fermions in a one-dimensional quasi-disordered optical lattice. By preparing the system in a far-from-equilibrium state and monitoring the remains of an imprinted density pattern, we identify a localized phase at high drive frequencies and an ergodic phase at low ones. These two distinct phases are separated by a dynamical phase transition which depends on both the drive frequency and the drive strength. Our observations are quantitatively supported by numerical simulations and are directly connected to the change in the statistical properties of the effective Floquet Hamiltonian.We acknowledge support from Technical University of Munich - Institute for Advanced Study, funded by the German Excellence Initiative and the European Union FP7 under grant agreement 291763, from the DFG grant no. KN 1254/1-1, the European Commission (UQUAM, AQuS) and the Nanosystems Initiative Munich (NIM)

Sedimentary Mo isotope record across the Holocene fresh–brackish water transition of the Black Sea

Mo isotope data on Black Sea sediments spanning the transition from Pleistocene oxic–limnic conditions to the prevailing anoxic marine conditions are presented. Samples were taken from a gravity core collected at a water depth of 396 m. Samples deposited under oxic bottom water conditions range from δ98/95MoMOMO − 2.2‰ to − 1.95‰ (MOMO = Mean Ocean Molybdenum) while samples deposited under anoxic bottom water conditions range from δ98/95MoMOMO − 1‰ to − 0.54‰. The change of sedimentary environment is also recorded in the Mo contents increasing from oxic to anoxic sediments. The Mo isotopic composition and invariably low Mo content of the oxic sediments deposited under oxic bottom water conditions are compatible with a pure detrital origin of the Mo, irrespective of whether the deposits are of limnic or brackish origin. Mo content and isotopic compositions are identical above and below a sulfidisation front, which originates from the diffusion of sulfur species and in-situ microbial activity after establishment of brackish bottom water conditions. Further, no signal of the overlaying sapropels is seen in the underlying sediments. Thus, transport of sulfur species has not mobilised Mo during diagenesis. The δ98/95MoMOMO values of anoxic samples indicate seawater as the dominant source of Mo. However, even the heaviest Mo value of the anoxic period recorded in this core is δ98/95MoMOMO = − 0.5‰, with an average of − 0.7‰ for all anoxic sediments, i.e. 0.7‰ lighter than seawater. All samples can be explained qualitatively as three component mixtures of detrital, dissolved riverine and marine Mo. For the lower units a mass balance model can be successfully applied. For the youngest unit mixing models do not yield satisfactory results given present day water fluxes. It is therefore likely that additional Mo isotope fractionation effects are involved. First order modelling suggests that the lighter δ98/95MoMOMO values of the most recent samples reflect the presence of some Mo remaining dissolved as MoO42− in a larger part of water column above the core depth, thus allowing for a preservation of a net fractionation between MoO42− and MoS42−. This hypothesis is supported by the fact that the H2S concentration critical for the MoO42− ↔ MoS42− chemical switch is found at about 400 m water depth in the present Black Sea, close to the depth at the sampling site. At greater depth, increased H2S concentrations lead to almost complete Mo removal, erasing the fractionation signal. Difference between Unit I samples from this study, and those from earlier publications (with samples taken at greater depth) may thus merely reflect the fraction of Mo scavenged at different depths. The degree of Mo scavenging in fossil black shales and the continental Mo contribution are both difficult to constrain. Therefore, black shales from restricted semi-enclosed basins may not document the Mo isotopic composition of coeval ocean waters. However, oceanic Mo is a dominant Mo source in these basins, and anoxic sediments give reliable minimum values for coeval ocean water Mo isotopic compositions