Optimized quantum nondemolition measurement of a field quadrature

We suggest an interferometric scheme assisted by squeezing and linear feedback to realize the whole class of field-quadrature quantum nondemolition measurements, from Von Neumann projective measurement to fully non-destructive non-informative one. In our setup, the signal under investigation is mixed with a squeezed probe in an interferometer and, at the output, one of the two modes is revealed through homodyne detection. The second beam is then amplitude-modulated according to the outcome of the measurement, and finally squeezed according to the transmittivity of the interferometer. Using strongly squeezed or anti-squeezed probes respectively, one achieves either a projective measurement, i.e. homodyne statistics arbitrarily close to the intrinsic quadrature distribution of the signal, and conditional outputs approaching the corresponding eigenstates, or fully non-destructive one, characterized by an almost uniform homodyne statistics, and by an output state arbitrarily close to the input signal. By varying the squeezing between these two extremes, or simply by tuning the internal phase-shift of the interferometer, the whole set of intermediate cases can also be obtained. In particular, an optimal quantum nondemolition measurement of quadrature can be achieved, which minimizes the information gain versus state disturbance trade-off

Soliton back-action evading measurement using spectral filtering

We report on a back-action evading (BAE) measurement of the photon number of fiber optical solitons operating in the quantum regime. We employ a novel detection scheme based on spectral filtering of colliding optical solitons. The measurements of the BAE criteria demonstrate significant quantum state preparation and transfer of the input signal to the signal and probe outputs exiting the apparatus, displaying the quantum-nondemolition (QND) behavior of the experiment.Comment: 5 pages, 5 figure

Teleportation of continuous variable polarisation states

This paper discusses methods for the optical teleportation of continuous variable polarisation states. We show that using two pairs of entangled beams, generated using four squeezed beams, perfect teleportation of optical polarisation states can be performed. Restricting ourselves to 3 squeezed beams, we demonstrate that polarisation state teleportation can still exceed the classical limit. The 3-squeezer schemes involve either the use of quantum non-demolition measurement or biased entanglement generated from a single squeezed beam. We analyse the efficacies of these schemes in terms of fidelity, signal transfer coefficients and quantum correlations

A New Targeting - A New Take-Up? Non-Take-Up of Social Assistance in Germany after Social Policy Reforms

We present first estimates of rates of non-take-up for social assistance in Germany after the implementation of major social policy reforms in 2005. The analysis is based on a microsimulation model, which includes a detailed description of the German social assistance programme. Our findings suggest a moderate decrease in non-take-up compared to estimates before the reform. In order to identify the determinants of claiming social assistance, we estimate a model of take-up behaviour which considers potential endogeneity of the benefit level. The estimations reveal that the degree of needs, measured as the social assistance benefit level a household is eligible for, and the expected duration of eligibility are the key determinants of the take-up decision, while costs of claiming seem to play a minor role.Diese Studie liefert erste Schätzungen für Quoten der Nicht-Inanspruchnahme für Leistungen der Grundsicherung nach SGB II und SGB XII. Die Analyse basiert auf einem Mikrosimulationsmodell, welches eine detaillierte Abbildung der deutschen Sozialgesetzgebung erlaubt. Unsere Ergebnisse deuten darauf hin, dass sich die Nicht-Inanspruchnahme im Vergleich zur Situation vor der Hartz-IV-Reform verringert hat. Um die Determinanten der Inanspruchnahme zu bestimmen, schätzen wir ein Modell des Inanspruchnahmeverhaltens. Die Schätzungen zeigen, dass die Höhe des Anspruchs sowie die erwartete Bezugsdauer die entscheidenden Einflussfaktoren darstellen, während die Kosten der Inanspruchnahme eine untergeordnete Rolle spielen

Squeezing more from a quantum nondemolition measurement

We use a stable, 5 dB, amplitude squeezed source for a quantum nondomolition (QND) experiment. The performance of our QND system is enhanced by an electro-optic feedforward loop which improve,, the signal transfer efficiency. At best, we measure a total signal transfer of 1.81 and conditional variance of 0.55

Multi-Mode Front Lens for Momentum Microscopy: Part II Experiments

We have experimentally demonstrated different operating modes for the front lenses of the momentum microscopes described in Part I. Measurements at energies from vacuum UV at a high-harmonic generation (HHG)-based source to the soft and hard X-ray range at a synchrotron facility validated the results of theoretical ray-tracing calculations. The key element is a ring electrode concentric with the extractor electrode, which can tailor the field in the gap. First, the gap-lens-assisted extractor mode reduces the field strength at the sample while mitigating image aberrations. This mode gave good results in all spectral ranges. Secondly, by compensating the field at the sample surface with a negative voltage at the ring electrode we can operate in zero-field mode, which is beneficial for operando experiments. Finally, higher negative voltages establish the repeller mode, which removes all slow electrons below a certain kinetic energy to eliminate the primary contribution to the space-charge interaction in pump-probe experiments. The switch from extractor to repeller mode is associated with a reduction in the k-field-of-view (10-20 % at hard-X-ray energies, increasing to ~50% at low energies). Real-space imaging also benefits from the new lens modes as confirmed by ToF-XPEEM imaging with 650 nm resolution.Comment: 22 pages, 9 figures, 56 reference

Non-Take-Up of Student Financial Aid: A Microsimulation for Germany

This paper estimates the percentage of students who do not take up their federal need-based student financial aid entitlements and sheds light on determinants of this behavior. Against the background that educational mobility in Germany is low although extensive student financial aid for needy students is available, it is crucial to know whether students assert their claims for student aid at all. To investigate non-take-up, we set up a microsimulation model for the German Socio-Economic Panel Study 2002-2013 and estimate the respective aid amounts students would have received, had they filed an application for need-based aid. The results indicate that about 40% of the eligible low-income students do not take up their entitlements. We employ instrumental variable techniques and a sample selection model to consider several potential explanatory factors for this behavior. Our results suggest that non-take-up is inversely related to the level of benefits, though the elasticity is rather low. Apart from that, a shorter expected duration of benefit receipt is related to a higher non-take-up rate, whereas the possibility to draw upon older siblings' experience with completing the complex application for aid is associated with higher probabilities to claim. Moreover, we find robust evidence that significantly more students socialized in the former socialist East Germany choose to take up student aid than similar West German students. Finally, in line with behavioral economic theory, debt aversion of highly impulsive and impatient students is associated with higher rates of non-take-up

Potential Effects of a Statutory Minimum Wage on the Gender Pay Gap A Simulation-Based Study for Germany

In a simulation-based study with data from the German Socio-Economic Panel Study (SOEP), we analyze the effects of the newly introduced statutory minimum wage of 8.50 Euro per working hour in Germany on the gender wage gap. In our first scenario where we abstain from employment effects, the pay differential is reduced by 2.5 percentage points from 19.6 % to 17.1 %, due to a reduction of the sticky-floor effect at the bottom of the wage distribution. In more realistic scenarios where we incorporate minimum wage effects on labor demand, a further reduction of the pay gap by 0.2 pp (1.2 pp) in case of a monopsonistic (neoclassical) labor market is achieved. However, this comes at the cost of job losses by which women are more strongly affected than men. The magnitude of job losses ranges between 0.2 % and 3.0 % of all employees. It is higher in a neoclassical market setting and positively related to the assumed wage elasticity