Qubit-portraits of qudit states and quantum correlations

The machinery of qubit-portraits of qudit states, recently presented, is consider here in more details in order to characterize the presence of quantum correlations in bipartite qudit states. In the tomographic representation of quantum mechanics, Bell-like inequalities are interpreted as peculiar properties of a family of classical joint probability distributions which describe the quantum state of two qudits. By means of the qubit-portraits machinery a semigroup of stochastic matrices can be associated to a given quantum state. The violation of the CHSH inequalities is discussed in this framework with some examples, we found that quantum correlations in qutrit isotropic states can be detected by the suggested method while it cannot in the case of qutrit Werner states.Comment: 12 pages, 4 figure

Entanglement Typicality

We provide a summary of both seminal and recent results on typical entanglement. By typical values of entanglement, we refer here to values of entanglement quantifiers that (given a reasonable measure on the manifold of states) appear with arbitrarily high probability for quantum systems of sufficiently high dimensionality. We work within the Haar measure framework for discrete quantum variables, where we report on results concerning the average von Neumann and linear entropies as well as arguments implying the typicality of such values in the asymptotic limit. We then proceed to discuss the generation of typical quantum states with random circuitry. Different phases of entanglement, and the connection between typical entanglement and thermodynamics are discussed. We also cover approaches to measures on the non-compact set of Gaussian states of continuous variable quantum systems.Comment: Review paper with two quotes and minimalist figure

The Political Repercussions of Homosexual Repression of Masculinity and Identity in Martin Sherman\u27s Bent

There are very few works of gay holocaust literature, mostly due to the fact that even post Nazi-Germany, homosexuality was outlawed. Bent, thereby serves as a testament of the persecution faced by homosexuals at the hands of the Nazis. This paper argues that the play is developed to display the main character Max having a better chance of survival if he denies his sexual preference and instead claims he is a Jew. While some may argue that such a decision privileges being Jewish over homosexuality, the final argument proves that this is not the case. Art is category of its own, one that is known for creating its own boundaries. In Bent, there is no privileging of one group over another rather the play serves as a display of the disjointedness of the various communities in Nazi German

On the classical capacity of quantum Gaussian channels

The set of quantum Gaussian channels acting on one bosonic mode can be classified according to the action of the group of Gaussian unitaries. We look for bounds on the classical capacity for channels belonging to such a classification. Lower bounds can be efficiently calculated by restricting to Gaussian encodings, for which we provide analytical expressions.Comment: 10 pages, IOP style. v2: minor corrections, close to the published versio

Invariant measures on multimode quantum Gaussian states

We derive the invariant measure on the manifold of multimode quantum Gaussian states, induced by the Haar measure on the group of Gaussian unitary transformations. To this end, by introducing a bipartition of the system in two disjoint subsystems, we use a parameterization highlighting the role of nonlocal degrees of freedom -- the symplectic eigenvalues -- which characterize quantum entanglement across the given bipartition. A finite measure is then obtained by imposing a physically motivated energy constraint. By averaging over the local degrees of freedom we finally derive the invariant distribution of the symplectic eigenvalues in some cases of particular interest for applications in quantum optics and quantum information.Comment: 17 pages, comments are welcome. v2: presentation improved and typos corrected. Close to the published versio

Tangibile/Intangibile. Dialoghi sul Design per i Territori 02

Il Network di Ricerca "D4T - Design for Territories" del Dipartimento di Design del Politecnico di Milano ha condotto un ciclo di focus group con l’obiettivo di attivare la discussione e il confronto sulla tematica del Design per i Territori. I focus group sono concepiti come momenti informali di impostazione critico-problematica, con l’obiettivo che diventino attivatori di un successivo dibattito allargato e condiviso. Il secondo focus group, tenutosi presso il Dipartimento di Design del Politecnico di Milano il 18 ottobre 2016, ha affrontato il tema del rapporto tra Tangibile e Intangibile cercando di rispondere ai seguenti interrogativi: in che modo il design si occupa del patrimonio e delle risorse tangibili e intangibili dei territori? In che modo il design è in grado di svelare le capacità di un territorio? Quali sono le azioni, gli strumenti e le strategie messe in atto? Gli ospiti invitati al second focus group sono stati: Daniela Calabi (Politecnico di Milano); Marco Ferreri (designer); Martha Friel (Centro Studi Silva Santagata; Università IULM); Lia Krucken (IPB Brasile); Federica Olivares (City Innovation Lab), Francesca Piredda (Politecnico di Milano); Raffaella Trocchianesi (Politecnico di Milano)

Quantum limits to incoherent imaging are achieved by linear interferometry

We solve the general problem of determining, through imaging, the three-dimensional positions of N weak incoherent pointlike emitters in an arbitrary spatial configuration. We show that a structured measurement strategy in which a passive linear interferometer feeds into an array of photodetectors is always optimal for this estimation problem, in the sense that it saturates the quantum Cramér-Rao bound. We provide a method for the explicit construction of the optimal interferometer. Further explicit results for the quantum Fisher information and the optimal interferometer design that attains it are obtained for the special case of one and two incoherent emitters in the paraxial regime. This work provides insights into the phenomenon of superresolution through incoherent imaging that has attracted much attention recently. Our results will find a wide range of applications over a broad spectrum of frequencies, from fluorescence microscopy to stellar interferometry

Partial scaling transform of multiqubit states as a criterion of separability

The partial scaling transform of the density matrix for multiqubit states is introduced to detect entanglement of quantum states. The transform contains partial transposition as a special case. The scaling transform corresponds to partial time scaling of subsystem (or partial Planck's constant scaling) which was used to formulate recently separability criterion for continous variables.A measure of entanglement which is a generalization of negativity measure is introduced being based on tomographic probability description of spin states.Comment: 16 pages, 5 figures, submitted to J. Phys. A: Math. Ge