4,712 research outputs found
Experimental Generation of Robust Entanglement from Classical Correlations via Local Dissipation
No full textWe experimentally show how classical correlations can be turned into quantum entanglement, via the presence of dissipation and the action of a CNOT gate. We first implement a simple two-qubit protocol in which entanglement production is not possible in the absence of such kind of noise, while it arises with its introduction, and is proportional to its amount. We then perform a more elaborate four-qubit experiment, by employing two hyperentangled photons initially carrying only classical correlations. We demonstrate a scheme where the entanglement is generated via local dissipation, with the advantage of being robust against local unitaries performed by an adversary
Structure of multipartite entanglement in random cluster-like photonic systems
Get PDFQuantum networks are natural scenarios for the communication of information among distributed parties, and the arena of promising schemes for distributed quantum computation.Measurement-based quantum computing is a prominent example of how quantum networking,embodied by the generation of a special class of multipartite states called cluster states, can be usedto achieve a powerful paradigm for quantum information processing. Here we analyze randomly generated cluster states in order to address the emergence of correlations as a function of the density of edges in a given underlying graph. We find that the most widespread multipartite entanglement does not correspond to the highest amount of edges in the cluster. We extend the analysis to higher dimensions, finding similar results, which suggest the establishment of small world structures in the entanglement sharing of randomised cluster states, which can be exploited in engineering more efficient quantum information carrier
Exploiting path-polarization hyperentangled photons for multiqubit quantum information protocols
Get PDFIn this thesis we describe and exploit a photonic source of hyperentangled states which allows the creation of a four qubit entangled state using path and polarization of two photons; this will be the main resource for a series of experiments that are linked to the main goal of exploring the advantages that quantum correlations brings in the aforementioned tasks. In particular we will focus onto showing that the same correlations which define the \emph{quantumness} of a state can be interpreted in two very different ways: either as something that introduces \emph{non-locality} between qubits, or something which reduces the \emph{information entropy} between qubits. Both interpretations allow the definition and observation of quantum advantage but, as we will show, the two views are not completely equivalent.
Our goal will be showing that quantum correlations can be seen as \emph{currency} that can be spent to perform tasks more efficiently than in the classical case
Experimental extractable work-based multipartite separability criteria
Get PDFA thermodynamic theory of quantum entanglement as well as the establishment of rigorous formal connections between the laws of thermodynamics and the phenomenology of entanglement are currently open areas of investigation. In this quest, a core problem is embodied by the understanding of the role that entanglement plays in processes of work extraction. Here, by considering information thermodynamics-based protocols, we answer the question “Is it possible to infer, quantitatively, quantum correlations by considering work-extraction schemes?”. Our experimental settings consist of suitably designed multi-photon optical interferometers able to address the case of both bipartite and multipartite entangled states. We compare the performance of such criteria to that of witnesses of entanglement based on the violation of Bell-like tests, showing their inherently different nature. Our work contributes strongly to the ongoing efforts in establishing photonic systems as a platform for experiments in information thermodynamics
Experimental lower bounds to the classical capacity of quantum channels
No full textWe show an experimental procedure to certify the classical capacity for noisy qubit channels. The method makes use of a fixed bipartite entangled state, where the system qubit is sent to the channel input and the set of local measurements, σx - σx, σy - σy, and σz - σz, is performed at the channel output and the ancilla qubit, thus without resorting to full quantum process tomography. The witness to the classical capacity is then achieved by reconstructing sets of conditional probabilities, noise deconvolution, and classical optimization of the pertaining mutual information. The performance of the method to provide lower bounds to the classical capacity is tested by a two-photon polarization entangled state in Pauli channels and amplitude damping channels. The measured lower bounds to the channels are in high agreement with the simulated data, which take into account both the experimental entanglement fidelity F=0.979±0.011 of the input state and the systematic experimental imperfections
Maxwell’s Demon in Photonic Systems
No full textPhotons are massless, noninteracting particles, and thermodynamics seems to be completely inappropriate in their description. Here we present two examples of the opposite: connecting thermodynamics with information through Maxwell’s Demon provides interesting insight on properties of light fields. This does not amount to directly applying thermodynamics to photons, but rather helps to obtain tools and concepts from thermodynamics to manipulate and evaluate the information content of light. The examples presented here pinpoint some of the challenges that arise when putting a thought experiment into practice and provide new insights into the relation between thermodynamic work and information
Il diritto penale nel canone di Mario Romano
No full textThis paper deals with the extension and the extraordinary scientific value of the works written by a great Master in Criminal Law, such as Mario Romano. The Author briefly presents some of the most relevant contributions given by Professor Mario Romano to the Criminal Science, first of all his "Commentario sistematico del codice penale" (Systematic Commentary on the penal code), a unique work. Finally, the paper talks about some topics which have been developed inside the work "Studi in onore di Mario Romano" (Studies in Honour of Mario Romano)
L'uno e il molteplice: su Catull. 5
No full textIn Catull. 5, the author cleverly works out two ancient topoi (‘let’s love, because the night/death is coming’; ‘kisses are the joy of lovers’), gaining a well balanced structure of the poem. In comparison with contemporary Graeco-Roman poetry (erotic epigrams – such as Philod. AP 9, 570 –, the Epitaph of Bion), both themes are handled with a remarkable taste for originality, especially in their ‘numerical’ aspects, in order to put special emphasis on the basic contrast between nox una and basia mille
Introduzione, a Mario Tobino, Il Clandestino
No full textL'introduzione presenta il libro più ambizioso di Mario Tobino, Il Clandestino, dedicato al racconto della sua esperienza con i gruppi clandestini della Resistenza Viareggina, libro con cui l'autore vinse il Premio Strega, nel 1962, imponendosi all'attenzione del grande pubblico dopo il successo dei libri manicomiali. Una nuova edizione in cui Paola Italia valorizza i materiali inediti dell'Archivio Tobino conservato presso l'Archivio Contemporaneo A. Bonsanti del Gabinetto GP Vieusseux di Firenze,Paola Italia presents an Introduction to the new edtion of Il Clandestino, the most ambitious of Mario Tobino's novels, dedicated to the story of his experience with the groups of the Tuscan Resistance when he was a psichiatric doctor ar Lucca. With this book the author won the Strega Prize, in 1962, attracting the attention of a wide public after the success of his psichiatric books. A new edition where Paola Italia enhances the unpublished material of Tobino Archive preserved in A. Bonsanti Contemporary Archive of G.P. Vieusseux Cabinet of Florence
Hyperentangled photon states on a chip
No full textIn order to achieve an optimal scalability, stability and compactness of complex quantum optical schemes based on a large number of elements, waveguide technology is of fundamental importance. Lately this technique has been implemented with experimental success with the introduction in the quantum domain of photonic integrated circuits built in various platforms and materials [1
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