Experimental Detection of Quantum Channels

We demonstrate experimentally the possibility of efficiently detecting properties of quantum channels and quantum gates. The optimal detection scheme is first achieved for non entanglement breaking channels of the depolarizing form and is based on the generation and detection of polarized entangled photons. We then demonstrate channel detection for non separable maps by considering the CNOT gate and employing two-photon hyperentangled states.Comment: 8 pages, 9 figure

Two-particle bosonic-fermionic quantum walk via 3D integrated photonics

Quantum walk represents one of the most promising resources for the simulation of physical quantum systems, and has also emerged as an alternative to the standard circuit model for quantum computing. Up to now the experimental implementations have been restricted to single particle quantum walk, while very recently the quantum walks of two identical photons have been reported. Here, for the first time, we investigate how the particle statistics, either bosonic or fermionic, influences a two-particle discrete quantum walk. Such experiment has been realized by adopting two-photon entangled states and integrated photonic circuits. The polarization entanglement was exploited to simulate the bunching-antibunching feature of non interacting bosons and fermions. To this scope a novel three-dimensional geometry for the waveguide circuit is introduced, which allows accurate polarization independent behaviour, maintaining a remarkable control on both phase and balancement.Comment: 4 pages, 5 figures + supplementary informatio

Integrated optical waveplates for arbitrary operations on polarization-encoded single-qubits

Integrated photonic technologies applied to quantum optics have recently enabled a wealth of breakthrough experiments in several quantum information areas. Path encoding was initially used to demonstrate operations on single or multiple qubits. However, a polarization encoding approach is often simpler and more effective. Two-qubits integrated logic gates as well as complex interferometric structures have been successfully demonstrated exploiting polarization encoding in femtosecond-laser-written photonic circuits. Still, integrated devices performing single-qubit rotations are missing. Here we demonstrate waveguide-based waveplates, fabricated by femtosecond laser pulses, capable to effectively produce arbitrary single-qubit operations in the polarization encoding. By exploiting these novel components we fabricate and test a compact device for the quantum state tomography of two polarization-entangled photons. The integrated optical waveplates complete the toolbox required for a full manipulation of polarization-encoded qubits on-chip, disclosing new scenarios for integrated quantum computation, sensing and simulation, and possibly finding application also in standard photonic devices

Fermionic statistics suppresses Fano resonances

Fano resonances and bound states with energy in the continuum are ubiquitous phenomena in different areas of physics. Observations, however, have been limited so far to single-particle processes. In this work we experimentally investigate the multi-particle case and observe Fano interference in a non-interacting two-particle Fano-Anderson model by considering propagation of two-photon states in engineered photonic lattices. We demonstrate that the quantum statistics of the particles, either bosonic or fermionic, strongly affects the decay process. Remarkably, we find that the Fano resonance, when two discrete levels are coupled to a continuum, is suppressed in the fermionic case

Anderson localization of entangled photons in an integrated quantum walk

Waves fail to propagate in random media. First predicted for quantum particles in the presence of a disordered potential, Anderson localization has been observed also in classical acoustics, electromagnetism and optics. Here, for the first time, we report the observation of Anderson localization of pairs of entangled photons in a two-particle discrete quantum walk affected by position dependent disorder. A quantum walk on a disordered lattice is realized by an integrated array of interferometers fabricated in glass by femtosecond laser writing. A novel technique is used to introduce a controlled phase shift into each unit mesh of the network. Polarization entanglement is exploited to simulate the different symmetries of the two-walker system. We are thus able to experimentally investigate the genuine effect of (bosonic and fermionic) statistics in the absence of interaction between the particles. We will show how different types of randomness and the symmetry of the wave-function affect the localization of the entangled walkers.Comment: 7 pages, 5 figures, revised version published on Nature Photonics 7, 322-328 (2013

Quantum simulation of bosonic-fermionic non-interacting particles in disordered systems via quantum walk

We report on the theoretical analysis of bosonic and fermionic non-interacting systems in a discrete two-particle quantum walk affected by different kinds of disorder. We considered up to 100-step QWs with a spatial, temporal and space-temporal disorder observing how the randomness and the wavefunction symmetry non-trivially affect the final spatial probability distribution, the transport properties and the Shannon entropy of the walkers.Comment: 13 pages, 10 figures. arXiv admin note: text overlap with arXiv:1101.2638 by other author

Research Progress on Homogeneous Fabrication of Large-Area Perovskite Films by Spray Coating

The bottleneck for large-scale processing within perovskite solar cells (PSCs) development is the stringent need for uniform thin films. On a lab scale, the spin coating methodology with acceptable uncertainty ensures a high level of uniformity with minimal roughness, no voids, and reproducible procedures. However, the technique is strongly limited for up-scaling because the uncertainty is out of range from the spin center to the edge, resulting in areas only up to a few cm2. In order to boost the industrialization of PSCs, the spray coating (SC) methodology can represent a good solution for achieving the goal of uniformity (in terms of crystal size, film thickness, and roughness) that, combined to a reduced active materials waste, compatible to roll2roll production line, will pave the way to PSCs mass production. In this critical review, we present the technological features of SC relevant to PSCs development and critically discuss the key points on which to address the focus for achieving optimal and reliable performances in connection with the fundamental higher potential of SC over spin-coating in allowing to control thin film homogeneity. This review can help in the commercialization of perovskite solar cells but also can contribute to the development of scale-up methodologies

Il Segretario, lo Statista. Aldo Moro dal centro-sinistra alla solidarietà nazionale

[Italiano]: Aldo Moro segretario della Democrazia cristiana, presidente del Consiglio in una alleanza di centro-sinistra, stratega dell’accordo di governo con il Partito comunista e infine vittima del terrorismo politico. Esaminando due diverse fasi della vita politica italiana – la stagione del centro-sinistra e la tragica vicenda della lotta armata – questo volume ripercorre, da molteplici prospettive, il tormentato percorso del leader politico che meglio riassume la storia d’Italia del secondo dopoguerra ./[English]: Aldo Moro, General Secretary of the Christian Democracy, Prime minister in an alliance of center-left, strategist of the government agreement with the Communist Party and finally victim of the political terrorism. Looking at two different stages of Italian political life - the season of center-left coalition and the tragic story of the armed struggle - this volume traces, from multiple perspectives, the tormented path of the leader politician that best sums up the Italian history of the second post-war period

Aragonite crystals grown on bones by reaction of CO2 with nanostructured Ca(OH)2 in the presence of collagen. Implications in archaeology and paleontology.

The loss of mechanical properties affecting archeological or paleontological bones is often caused by demineralization processes that are similar to those driving the mechanisms leading to osteoporosis. One simple way to harden and to strengthen demineralized bone remains could be the in situ growth of CaCO3 crystals in the aragonite polymorph - metastable at atmospheric pressure -which is known to have very strong mechanical strength in comparison with the stable calcite. In the present study the controlled growth of aragonite crystals was achieved by reaction between atmospheric CO2 and calcium hydroxide nanoparticles in the presence of collagen within the deteriorated bones. In a few days the carbonation of Ca(OH)2 particles led to a mixture of calcite and aragonite, increasing the strength of the mineral network of the bone. Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) and Fourier transform infrared (FT-IR) spectrometry showed that aragonite crystallization was achieved. The effect of the aragonite crystal formation on the mechanical properties of the deteriorated bones was investigated by means of X-rays microtomography, helium porosimetry, atomic force microscopy (AFM), and Vickers microhardness techniques. All these data enabled to conclude that the strength of the bones increased of a factor of 50-70% with respect to the untreated bone. These results could have immediate impact for preserving archeological and paleontological bone remains