1,851 research outputs found
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
- …