Co-sputtered MoRe thin films for carbon nanotube growth-compatible superconducting coplanar resonators

Molybdenum rhenium alloy thin films can exhibit superconductivity up to critical temperatures of $T_c=15\mathrm{K}$. At the same time, the films are highly stable in the high-temperature methane / hydrogen atmosphere typically required to grow single wall carbon nanotubes. We characterize molybdenum rhenium alloy films deposited via simultaneous sputtering from two sources, with respect to their composition as function of sputter parameters and their electronic dc as well as GHz properties at low temperature. Specific emphasis is placed on the effect of the carbon nanotube growth conditions on the film. Superconducting coplanar waveguide resonators are defined lithographically; we demonstrate that the resonators remain functional when undergoing nanotube growth conditions, and characterize their properties as function of temperature. This paves the way for ultra-clean nanotube devices grown in situ onto superconducting coplanar waveguide circuit elements.Comment: 8 pages, 6 figure

Optomechanical coupling and damping of a carbon nanotube quantum dot

Carbon nanotubes are excellent nano-electromechanical systems, combining high resonance frequency, low mass, and large zero-point motion. At cryogenic temperatures they display high mechanical quality factors. Equally they are outstanding single electron devices with well-known quantum levels and have been proposed for the implementation of charge or spin qubits. The integration of these devices into microwave optomechanical circuits is however hindered by a mismatch of scales, between typical microwave wavelengths, nanotube segment lengths, and nanotube deflections. As experimentally demonstrated recently in [Blien et al., Nat. Comm. 11, 1363 (2020)], coupling enhancement via the quantum capacitance allows to circumvent this restriction. Here we extend the discussion of this experiment. We present the subsystems of the device and their interactions in detail. An alternative approach to the optomechanical coupling is presented, allowing to estimate the mechanical zero point motion scale. Further, the mechanical damping is discussed, hinting at hitherto unknown interaction mechanisms.Comment: 17 pages, 13 figures, 3 table

Employer wage subsidies and wages in Germany: empirical evidence from individual data

In Germany, targeted wage subsidies to employers are an important instrument of active labor market policy. This paper compares the wages of individuals taking up a subsidized job with those of otherwise similar individuals who found an unsubsidized job, combining propensity score matching with a differences-in-differences strategy. The results indicate for the short-run that subsidized jobs are not associated with gains or losses regarding daily wages. Nonetheless, because subsequent employment rates of subsidized persons are higher on average, we find a positive relationship between cumulated wages and subsidization

The Importance of Spatial Autocorrelation for Regional Employment Growth in Germany

In analyzing the disparities of the regional developments in the volume of employment in Germany, in the recent empirical literature so called shift-share-regression-models are frequently applied. However, these models usually neglect spatial interdependencies, even though such interdependencies are likely to occur on a regional level. Therefore, this paper focuses on the importance of spatial dependencies using spatial autocorrelation in order to analyze regional employment development. Spatial dependency in the form of spatial lag, spatial error and cross regressive model are compared. The results indicate that the exogenous variables' spatial lag sufficiently explains the spatial autocorrelation of regional employment growth

Regional Unemployment and New Economic Geography

Regional labor markets are characterized by huge disparities. The literature on the wage curve argues that there exists a negative relationship between unemployment and wages. However, this literature cannot explain how disparities of these variables between regions endogenously arise. In contrast, the New Economic Geography analyzes how disparities of regional goods markets endogenously arise, but usually ignores unemployment. Therefore, this paper discusses regional unemployment disparities by introducing efficiency wages into the New Economic Geography. This model shows how disparities of regional goods and labor markets endogenously arise through the interplay of increasing returns to scale, transport costs and migration

Arbeitsmarkt und Demographie

Im vorliegenden Beitrag werden die wechselseitigen Beziehungen von demographischen Veränderungen und Arbeitsmarktentwicklungen anhand eines Literaturüberblicks diskutiert. Insbesondere werden die Effekte von demographischen Strukturen und Prozessen auf die Lohnstruktur und auf die Arbeitslosigkeit präsentiert, wobei sowohl Mikro- als auch Makroansätze diskutiert und die Implikationen der Bevölkerungsalterung für den Arbeitsmarkt besprochen werden. In Mikroansätzen werden z.B. altersspezifische Profile der Humankapitalbildung als optimale Lösung eines individuellen Entscheidungsproblems modelliert. Im Gegensatz dazu werden in Makroansätzen die Beziehung von Makrovariablen, z.B. Jugendarbeitslosigkeit und Besetzungsstärke der eigenen Kohorte, modelliert. Schließlich stellen wir verschiedene theoretische Perspektiven vor, welche Effekte arbeitsmarktrelevanter Faktoren auf die Fertilität untersuchen

Arbeitslosigkeit und Stellenannahmebereitschaft: Erste Ergebnisse eines Faktoriellen Survey Moduls

Matching individuals to jobs is a fundamental problem in any labour market. This paper focuses on job characteristics, such as wages, job quality, and distance from the current place of residence, and the impact of these characteristics on the willingness of employed and unemployed individuals to accept new job offers. Using an experimental factorial survey module (FSM) implemented in the fifth wave of a large population survey (Panel Study Labour Market and Social Security), the willingness of employed and unemployed labour market participants to accept new job offers was compared while considering job characteristics like gain of income or commuting distance. In this study, unemployed and employed individuals received the same set of hypothetical job offers. Consistent with theoretical arguments, the about 20,000 evaluations provided by about 4,000 respondents showed that unemployed participants generally exhibit a greater willingness to accept new job offers than employed ones. Moreover, unemployed individuals were likely to make more concessions than employed individuals with respect to job quality, such as accepting fixed-term job offers. Interestingly, little evidence for different decision-making or weightings of mobility costs was found, which enables us to conclude that interregional unemployment disparities can scarcely be explained by unemployed individuals lacking the willingness to work or relocate

Development in Regional Labour Market in Germany: a Comparative Analysis of the Forecasting Performance of Competing Statistical Models

The aim of this paper is to forecast regional employment patterns in West German regions. After a brief exposition of key labour market issues, Artificial Neural Network (ANN) techniques are proposed as a new tool to generate reliable short term employment forecasts at a regional level. A variety of ANN models are developed and compared. Comparison with methods commonly applied to panel data, such as GMM (Generalised Method of Moments), confirms the ability of ANNs to capture complex data structures in a multi-regional context