High-fidelity copies from a symmetric 1 to 2 quantum cloning machine

A symmetric 1 to 2 quantum cloning machine (QCM) is presented that provides high-fidelity copies with $0.90 \le F \le 0.95$ for all pure (single-qubit) input states from a given meridian of the Bloch sphere. \cor{Emphasize is placed especially on the states of the (so-called) Eastern meridian, that includes the computational basis states \ketm{0}, \ketm{1} together with the diagonal state \ketm{+} = \frac{1}{\sqrt{2}} (\ketm{0} + \ketm{1}), for which suggested cloning transformation is shown to be optimal.} In addition, we also show how this QCM can be utilized for eavesdropping in Bennett's B92 protocol for quantum key distribution with a substantial higher success rate than obtained for universal or equatorial quantum copying.Comment: 2 figures, 20 reference

The Distribution and Heterogeneity of Technical Efficiency within Industries: An Empirical Assessment

This paper analyzes the distribution of technical efficiency within manufacturing industries. Using a representative sample of 35,000 firms in 255 industries of the German cost structure census, technical efficiencies are estimated by applying a deterministic frontier production function with firmspecific fixed effects. A new measure is also introduced for characterizing the extent of heterogeneity within an industry that is robust with regard to extreme values of a few small firms. It was found that the level of intra-industry heterogeneity is mainly determined by an industries' average technical efficiency, average firm size, capital intensity and the rate of new firm formation. Most strikingly, we find that in about 95 percent of industries the distribution of technical efficiency is skewed to the right, not to the left as is commonly assumed.Technical efficiency; Heterogeneity; Deterministic production function frontier

Pricing Rare Event Risk in Emerging Markets

This paper solves the pricing problem of an merging market debt contract in which the borrower’s economy is subject to rare event risk. Our model combines elements of a reduced form and a structural model of debt pricing. Rare event risk is modeled as a sudden event in fundamentals, and we study the role of the debt contract in providing risk sharing between the borrower and the lender. The two main frictions under consideration in our equilibrium model are limited participation of the lender through the debt contract, and heterogeneous beliefs between the borrower and the lender about the likelihood of a rare event. We solve for the rate of interest, the credit spread, the risk premium, the write-off (recovery rate) in case of default, and the dynamics of the debt contract in non-default times. We find that limited participation combined with heterogeneous beliefs has strong e®ects on the level and variability of the debt contract propertiesRare Event Risk, Emerging Markets, Exchange Economy, Heterogeneous Beliefs, Incomplete Market

Geography vs. Institutions at the Village Level

There is a well-known debate about the roles of geography versus institutions in explaining the long-term development of countries. These debates have usually been based on cross-country regressions where questions about parameter heterogeneity, unobserved heterogeneity, and endogeneity cannot easily be controlled for. The innovation of Acemoglu, Johnson and Robinson (2001) was to address this last point by using settler mortality as an instrument for geography-induced endogenous institutions and found that this supported their line of reasoning. We believe there is value-added to consider this debate at the micro level within a country as particularly questions of parameter heterogeneity and unobserved heterogeneity are likely to be smaller than between countries. Moreover, at the micro level it is possible to identify more precise transmission mechanisms from geography via institutions to economic development outcomes. In particular, we examine the determinants of economic development across villages on the Indonesian Island of Sulawesi and find that geography-induced endogenous emergence of land rights is the critical institutional link between geographic conditions and technological change. We therefore highlight and empirically validate a new transmission channel from endogenously generated institutions on economic development.geography, migration, land rights, institutions, technology adoption, agricultural development, Indonesia

Measuring performance heterogeneity within groups: A two-dimensional approach

We introduce a new two-dimensional measure for the heterogeneity of performance within groups of economic units. This measure accounts both, for the relative performance of the single units of groups and their relative size. We demonstrate that the new measure leads to a much more differentiated description of heterogeneity than alternative measures, for example, the mean or range. In particular, we provide an example to demonstrate that the proposed measure of heterogeneity is relatively robust with regard to extreme values of units ("outliers") with a relatively small size. -- Wir stellen ein neues zweidimensionales Maß für die Heterogenität der Leis-tungsfähigkeit innerhalb von Gruppen ökonomischer Einheiten vor. Dieses Maß berücksichtigt neben der Leistungsfähigkeit auch die relative Größe der betreffen-den Einheiten. Wir zeigen, dass dieses neue Maß die Heterogenität innerhalb von Gruppen wesentlich differenzierter beschreibt als alternative Maße, wie etwa das arithmetische Mittel und die Spannweite. Anhand eines numerischen Beispiels kann gezeigt werden, dass unser Maß vergleichsweise robust gegenüber extremen Werten (Ausreißern) relativ kleiner Einheiten ist.Performance,heterogeneity,dispersion measures,Leistungsfähigkeit,Heterogenität,Streuungsmaße

What causes cross-industry differences of technical efficiency? An empirical investigation

Using micro-level panel data of about 35,000 firms from the German Cost Structure Census, we analyze the differences of technical efficiency across industries. Technical efficiency is estimated by firms fixed effects. One striking result is that the distribution of technical efficiency across industries is positively skewed. This is because the efficiency distribution is truncated at the lower end due to the least efficient firms which exit the market. We investigate the causes of technical efficiency differences across industries. Our econometric analyses provide evidence that capital and human capital intensity, the degree of vertical specialization as well as new firm formation rate are important for explaining the average technical efficiency of an industry. -- Anhand von Mikro-Daten für ca. 35.000 Unternehmen aus der deutschen Kostenstrukturstatistik analysieren wir Branchenunterschiede der technischen Effizienz. Dabei wird die technische Effizienz als ein unternehmensspezifischer fixer Effekt spezifiziert. Ein wesentliches Ergebnis besteht in dem Befund, dass die Verteilung der technischen Effizienz über die Branchen eine positive Schiefe aufweist. Der Grund hierfür ist offenbar darin zu sehen, dass die Effizienzverteilung innerhalb der Branchen jeweils am unteren Ende abgeschnitten ist, da die Unternehmen mit relativ geringer Effizienz aus dem Markt ausscheiden müssen. Nach den Ergebnissen unserer ökonometrischen Analyse spielen die Sachkapital- und Humankapitalintensität, das Ausmaß vertikaler Spezialisierung sowie die das Ausmaß an Marktzutritten für die Erklärung der durchschnittlichen technischen Effizienz einer Branche eine wesentliche Rolle.Technical efficiency,cross-industry study,efficiency distribution,Technische Effizienz,Branchenunterschiede,Effizienzverteilung

Geography vs. Institutions at the Village Level

There is a well-known debate about the roles of geography versus institutions in explaining the long-term development of countries. These debates have usually been based on cross-country regressions where questions about parameter heterogeneity, unobserved heterogeneity, and endogeneity cannot easily be controlled for. The innovation of Acemoglu, Johnson and Robinson (2001) was to address this last point by using settler mortality as an instrument for geography-induced endogenous institutions and found that this supported their line of reasoning. We believe there is value-added to consider this debate at the micro level within a country as particularly questions of parameter heterogeneity and unobserved heterogeneity are likely to be smaller than between countries. Moreover, at the micro level it is possible to identify more precise transmission mechanisms from geography via institutions to economic development outcomes. In particular, we examine the determinants of economic development across villages on the Indonesian Island of Sulawesi and find that geography-induced endogenous emergence of land rights is the critical institutional link between geographic conditions and technological change. We therefore highlight and empirically validate a new transmission channel from endogenously generated institutions on economic development.geography, migration, land rights, institutions, technology adoption, agricultural development, Indonesia

Purchase and redemption decisions of mutual fund investors and the role of fund families

This paper investigates the purchases and redemptions of a large cross-sectional sample of German equity funds. We find that investors punish bad performance by selling their shares, but also have a tendency to sell winners. Investors in large fund families show higher sales and redemption rates. Furthermore, family size also affects the flow-performance relationship. On the one hand, investors in large families punish bad performance more, on the other, they also tend to sell winners more. Finally, we find that inner-family rankings play an important role for redemptions, with investors strongly redeeming their shares from intra-family losers. --Mutual funds,fund family,flow-performance relationship