arXiv subjects

G. Di Nepi

Publications and source records attributed to G. Di Nepi.

4 recordsLinked to original sources

arXiv2004

Nonlocality tests of Bell Inequalities and of Hardy's "ladder theorem" without "supplementary assumptions"

We have experimentally tested the non local properties of the states generated by a high brilliance source of entanglement which virtually allows the direct measurement of the full set of photon pairs created by the basic QED process implied by the parametric quantum scattering. Standard Bell measurements and Bell's inequality violation test have been realized over the entire cone of emission of the degenerate pairs. By the same source we have verified the Hardy's ladder theory up to the 20th step and the contradiction between the standard quantum theory and the local realism has been tested for 41% of entangled pairs. PACS: 03.65.Ud, 03.67.Mn, 42.65.Lm

quant-ph↗

arXiv2003

Universal ultrabright source of entangled photon states: generation and tomographic analysis of Werner states and of Maximally Entangled Mixed States

A novel ultrabright parametric source of polarization entangled photon pairs with striking spatial characteristics is reported. The distribution of the output electromagnetic k-modes excited by Spontaneous Parametris Down Conversion and coupled to the output detectors can be very broad. It could coincide with the full set of phase-matched excited modes, at least in principle. In this case a relevant conditional quasi-pure output state should be realized. By these (approximate) states realized over a full Entanglement-Ring output distribution, the non local properties of the generated entanglement has been tested by standard Bell measurements and by Ou-Mandel interferometry. A novel ''mode-patchwork'' technique based on the quantum superposition principle is adopted to synthesize in a straightforward and reliable way any kind of mixed-states, of large conceptual and technological interest in modern Quantum Information. Tunable Werner states and Maximally Entangled Mixed States (MEMS) have indeed been created by the new technique and investigated by quantum tomography. A thorough study of the entropic and nonlocal properties of these states has been undertaken experimentally and theoretically, by a unifying variational approach.

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arXiv2003

Experimental Detection of Entanglement with Polarized Photons

We report on the first experimental realization of the entanglement witness for polarization entangled photons. It represents a recently discovered significant quantum information protocol which is based on few local measurements. The present demonstration has been applied to the so-called Werner states, a family of ''mixed'' quantum states that include both entangled and non entangled states. These states have been generated by a novel high brilliance source of entanglement which allows to continuously tune the degree of mixedness.

quant-ph↗

arXiv2003

Violation of Bell inequalities and Quantum Tomography with Pure-states, Werner-states and Maximally Entangled Mixed States created by a Universal Quantum Entangler

Entangled pure-states, Werner-states and generalized mixed-states of any structure, spanning a 2x2 Hilbert space are created by a novel high-brilliance universal source of polarization-entangled photon pairs. The violation of a Bell inequality has been tested for the first time with a pure-state, indeed a conceptually relevant ideal condition, and with Werner-states. The generalized ''maximally entangled mixed states'' (MEMS) were also synthetized for the first time and their exotic properties investigated by means of a quantum tomographic technique.

quant-ph↗