de Finetti reductions for correlations

When analysing quantum information processing protocols one has to deal with large entangled systems, each consisting of many subsystems. To make this analysis feasible, it is often necessary to identify some additional structure. de Finetti theorems provide such a structure for the case where certain symmetries hold. More precisely, they relate states that are invariant under permutations of subsystems to states in which the subsystems are independent of each other. This relation plays an important role in various areas, e.g., in quantum cryptography or state tomography, where permutation invariant systems are ubiquitous. The known de Finetti theorems usually refer to the internal quantum state of a system and depend on its dimension. Here we prove a different de Finetti theorem where systems are modelled in terms of their statistics under measurements. This is necessary for a large class of applications widely considered today, such as device independent protocols, where the underlying systems and the dimensions are unknown and the entire analysis is based on the observed correlations.Comment: 5+13 pages; second version closer to the published one; new titl

Molecular phylogenetics of Melastomataceae and Memecylaceae

Melastomataceae are among the most abundant and diversified groups of plants throughout the tropics, but their intrafamily relationships and morphological evolution are poorly understood. Here we report the results of parsimony and maximum likelihood (ML) analyses of cpDNA sequences from the rbcL and ndhF genes and the rpl16 intron, generated for eight outgroups (Crypteroniaceae, Alzateaceae, Rhynchocalycaceae, Oliniaceae, Penaeaceae, Myrtaceae, and Onagraceae) and 54 species of melastomes. The sample represents 42 of the family’s currently recognized ~150 genera, the 13 traditional tribes, and the three subfamilies, Astronioideae, Melastomatoideae, and Memecyloideae (= Memecylaceae DC.). Parsimony and ML yield congruent topologies that place Memecylaceae as sister to Melastomataceae. Pternandra, a Southeast Asian genus of 15 species of which five were sampled, is the firstbranching Melastomataceae. This placement has low bootstrap support (72%), but agrees with morphological treatments that placed Pternandra in Melastomatacaeae because of its acrodromal leaf venation, usually ranked as a tribe or subfamily. The interxylary phloem islands found in Memecylaceae and Pternandra, but not most other Melastomataceae, likely evolved in parallel because Pternandra resembles Melastomataceae in its other wood characters. A newly discovered plesiomorphic character in Pternandra, also present in Memecylaceae, is a fibrous anther endothecium. Higher Melastomataceae lack an endothecium as do the closest relatives of Melastomataceae and Memecylaceae. The next deepest split is between Astronieae, with anthers opening by slits, and all remaining Melastomataceae, which have anthers opening by pores. Within the latter, several generic groups, corresponding to traditional tribes, receive solid statistical support, but relationships among them, with one exception, are different from anything predicted on the basis of morphological data. Thus, Miconieae and Merianieae are sister groups, and both are sister to a trichotomy of Bertolonieae, Microlicieae + Melastomeae, and Dissochaeteae + Blakeeae. Sonerileae/Oxysporeae are nested within Dissochaeteae, Rhexieae within Melastomeae, and African and Asian Melastomeae within neotropical Melastomeae. These findings have profound implications for our understanding of melastome morphological evolution (and biogeography), implying, for example, that berries evolved from capsules minimally four times, stamen connectives went from dorsally enlarged to basal/ventrally enlarged, and loss of an endothecium preceded poricidal dehiscence

A new Miconia (Melastomatacaeae) from Bolivia, with remarks on angular-branched species in the Andes

A new species of Melastomataceae frorm Bolivia is described, illustrated and placed in a phenetic context within Miconia, a genus of 1000 species and about 2000 published names. Miconia quadrialata is readily distinguished from its Congeners by two-colored leaves and sharply four-angular and winged branchlets. A search for quadrangular-branched miconias revealed that 12 of 15 such species (in four sections), including the new species, occur in cloud forest in the Andes, raising the question of the adaptive significance of quadrangular branchlets

Historical biogeography of Melastomataceae

Melastomataceae and Memecylaceae are pantropically distributed sister groups for which an ndhF gene phylogeny for 91 species in 59 genera is here linked with Eurasian and North American fossils in a molecular clock approach to biogeographical reconstruction. Nine species from the eight next-closest families are used to root phylogenetic trees obtained under maximum likelihood criteria. Melastomataceae comprise ∼3000 species in the neotropics, ∼1000 in tropical Asia, 240 in Africa, and 225 in Madagascar in 150-166 genera, and the taxa sampled come from throughout this geographic range. Based on fossils, ranges of closest relatives, tree topology, and calibrated molecular divergences, Melastomataceae initially diversified in Paloecene/Eocene times in tropical forest north of the Tethys. Their earliest (Eocene) fossils are from northeastern North America, and during the Oligocene and Miocene melastomes occurred in North America as well as throughout Eurasia. They also entered South America, with earliest (Oligocene) South American fossils representing Merianieae. One clade (Melastomeae) reached Africa from the neotropics 14-12 million years ago and from there spread to Madagascar, India, and Indochina. Basalmost Melastomataceae (Kibessieae, Astronieae) are species-poor lineages restricted to Southeast Asia. However, a more derived Asian clade (Sonerileae/Dissochaeteae) repeatedly reached Madagascar and Africa during the Miocene and Pliocene. Contradicting earlier hypotheses, the current distribution of Melastomataceae is thus best explained by Neogene long-distance dispersal, not Gondwana fragmentation

A de Finetti representation theorem for infinite dimensional quantum systems and applications to quantum cryptography

According to the quantum de Finetti theorem, if the state of an N-partite system is invariant under permutations of the subsystems then it can be approximated by a state where almost all subsystems are identical copies of each other, provided N is sufficiently large compared to the dimension of the subsystems. The de Finetti theorem has various applications in physics and information theory, where it is for instance used to prove the security of quantum cryptographic schemes. Here, we extend de Finetti's theorem, showing that the approximation also holds for infinite dimensional systems, as long as the state satisfies certain experimentally verifiable conditions. This is relevant for applications such as quantum key distribution (QKD), where it is often hard - or even impossible - to bound the dimension of the information carriers (which may be corrupted by an adversary). In particular, our result can be applied to prove the security of QKD based on weak coherent states or Gaussian states against general attacks.Comment: 11 pages, LaTe

1989 und die Folgen : deutsche Gegenwartsgeschichte im Nachwendefilm

In a significant way Schlöndorff's films "Die verlorene Ehre der Katharina Blum" and "Die Stille nach dem Schuss" reflect the change in intellectual discourse about politics in Germany after 1945, presenting it with different aesthetic means. The film "Die Verlorene Ehre der Katharina Blum" is a reconstruction of the ideological situation in 1968 in which Schlöndorff in close cooperation with Böll takes a provocative position. In "Die Stille nach dem Schuss", however, Schlöndorff outlines the public discussion about the political and ideological antagonisms in the former GDR and the coming to terms with its Stasi-past after 1989. Schlöndorff also critically evaluates his own position as a Western intellectual towards the GDR and in Germany after reunification. In contrast, the recent films "Der Baader Meinhof Komplex" and "Die innere Sicherheit" open up new perspectives on the extraparliamentary opposition and the Baader Meinhof group. Eichinger´s and Edel´s film puts the story into a historical context and denounces all heroism, whereas Petzold´s film shows the consequences of this political movement focusing on people´s private life in a way characteristic of the so-called "Berlin School".Schlöndorffs Filme "Die verlorene Ehre der Katharina Blum" und "Die Stille nach dem Schuss" spiegeln in signifikanter Weise einen Wandel des intellektuellen Diskurses über Politik in Deutschland nach 1945, zugleich konturieren sie ihn mit unterschiedlichen ästhetischen Mitteln. "Die Verlorene Ehre der Katharina Blum" rekonstruiert die ideologische Situation des Jahres 1968, in der Schlöndorff in enger Zusammenarbeit mit Böll eine markante Position bezieht, "Die Stille nach dem Schuss" skizziert demgegenüber eine Bewusstseinslage, in der erstmals nach der Wende des Jahres 1989 die politischen und ideologischen Widersprüche innerhalb der früheren DDR und die Aufarbeitung der Stasivergangenheit offen thematisiert werden. Dabei beleuchtet Schlöndorff zugleich kritisch die eigene Haltung als westlicher Intellektueller gegenüber der DDR und im vereinigten Deutschland. Dagegen machen die neueren Filme "Der Baader Meinhof Komplex" und "Die innere Sicherheit" auf je unterschiedliche Weise die Neubewertung der Außerparlamentarischen Opposition und der Baader Meinhof Gruppe deutlich, die ebenfalls nach 1989 einsetzt. Dabei führt der Film von Eichinger und Edel zu einer Historisierung und ideologiekritischen Entheroisierung, seine Präsentation einer Phase der politischen Opposition in Deutschland wird mit Mitteln des action-Films entfaltet. Petzolds Film dagegen zeigt die Folgen dieser Bewegung in der für die "Berliner Schule" typischen Konzentration auf das Private

Quantum Key Distribution Using Quantum Faraday Rotators

We propose a new quantum key distribution (QKD) protocol based on the fully quantum mechanical states of the Faraday rotators. The protocol is unconditionally secure against collective attacks for multi-photon source up to two photons on a noisy environment. It is also robust against impersonation attacks. The protocol may be implemented experimentally with the current spintronics technology on semiconductors.Comment: 7 pages, 7 EPS figure

Axial charges of octet and decuplet baryons

We present a study of axial charges of baryon ground and resonant states with relativistic constituent quark models. In particular, the axial charges of octet and decuplet $N$, $\Sigma$, $\Xi$, $\Delta$, $\Sigma^*$, and $\Xi^*$ baryons are considered. The theoretical predictions are compared to existing experimental data and results from other approaches, notably from lattice quantum chromodynamics and chiral perturbation theory. The relevance of axial charges with regard to $\pi$-dressing and spontaneous chiral-symmetry breaking is discussed