Physics within a quantum reference frame

We investigate the physics of quantum reference frames. Specifically, we study several simple scenarios involving a small number of quantum particles, whereby we promote one of these particles to the role of a quantum observer and ask what is the description of the rest of the system, as seen by this observer? We highlight the interesting aspects of such questions by presenting a number of apparent paradoxes. By unravelling these paradoxes we get a better understanding of the physics of quantum reference frames.Comment: 11 pages, 4 figures. v2: Published versio

Semiclassical limit of the entanglement in closed pure systems

We discuss the semiclassical limit of the entanglement for the class of closed pure systems. By means of analytical and numerical calculations we obtain two main results: (i) the short-time entanglement does not depend on Planck's constant and (ii) the long-time entanglement increases as more semiclassical regimes are attained. On one hand, this result is in contrast with the idea that the entanglement should be destroyed when the macroscopic limit is reached. On the other hand, it emphasizes the role played by decoherence in the process of emergence of the classical world. We also found that, for Gaussian initial states, the entanglement dynamics may be described by an entirely classical entropy in the semiclassical limit.Comment: 8 pages, 2 figures (accepted for publication in Phys. Rev. A

Decoherence induced by a phase-damping reservoir

A phase damping reservoir composed by $N$-bosons coupled to a system of interest through a cross-Kerr interaction is proposed and its effects on quantum superpo sitions are investigated. By means of analytical calculations we show that: i-) the reservoir induces a Gaussian decay of quantum coherences, and ii-) the inher ent incommensurate character of the spectral distribution yields irreversibility . A state-independent decoherence time and a master equation are both derived an alytically. These results, which have been extended for the thermodynamic limit, show that nondissipative decoherence can be suitably contemplated within the EI D approach. Finally, it is shown that the same mechanism yielding decoherence ar e also responsible for inducing dynamical disentanglement.Comment: 8 pages, 3 figure

Correlating Local Quantum Reality with Causally Disconnected Choices

In 1935, Einstein, Podolsky, and Rosen claimed the incompleteness of quantum mechanics by assuming that local actions cannot influence the elements of reality in a distant location. In this Letter, we show that Alice's local quantum operations can be correlated with the quantum reality of observables in the causally disconnected laboratory of Bob. We propose a modified optical quantum eraser experiment that can be implemented using current technology for verifying our theoretical predictions, without any need for retrodiction. We simulate such an experiment using IBM quantum computers

A Kinetic Approach to Photomineralization of Methane in Air by Membranes Based on TiO2/WO3

Photomineralization of methane in air (10.0-1,000 ppm (mass/volume) of C) at 100% relative humidity (dioxygen as oxygen donor), was systematically studied at 318 \ub1 3 K, in an annular laboratory-scale reactor, by photocatalytic membranes immobilising titanium dioxide and tungsten trioxide as co-photocatalysts. Kinetics of both substrate disappearance, to yield intermediates, and total organic carbon (TOC) disappearance, to yield carbon dioxide, were followed. A kinetic model was employed, from which, by a set of differential equations, four final optimised parameters, k1 and K1, k2 and K2, were calculated, able to fit the whole kinetic profile adequately. Modelling of quantum yields, as a function of substrate concentration and irradiance, as well as of concentration of photocatalysts, was carried out very satisfactorily. Kinetics of hydroxyl radicals reacting between themselves, leading to hydrogen peroxide, other than with substrate or intermediates leading to mineralization, were considered, paralleled by second competition kinetics involving superoxide radical anion. When using appropriate blends of the two photocatalysts, limiting quantum yields \uf046 1e values increase considerably and approach the maximum allowable value for the investigated molecule, in a much wider range of irradiances than that shown by the single catalysts mainly at low irradiances. This may be interpreted by strong competition kinetics of superoxide radicals generated by the catalyst defects, in the corresponding range of high irradiances. By this way, operation at high irradiance values is possible, without losing any efficiency for the mineralization process

Open-slope, translational submarine landslide in a tectonically active volcanic continental margin (Licosa submarine landslide, southern Tyrrhenian Sea)

The southern Tyrrhenian continental margin is the product of Pliocene-Recent back-arc extension. An area of approximately 30 km of gentle (about 1.5°) lower slope of the last glacial outer shelf sedimentary wedge in water depths of between 200 and 300 m failed between 14 and 11 ka BP. We approached the landslide by multibeam and sub-bottom profiler surveying, high-resolution multichannel seismics, and coring for stratigraphic and geotechnical purposes. With regard to a slope-stability analysis, we carried out an assessment of the stratigraphic and structural setting of the area of the Licosa landslide. This analysis revealed that the landslide detached along a marker bed that was composed of the tephra layer Y-5 (c. 39 ka). Several previously unknown geological characteristics of the area are likely to have affected the slope stability. These are the basal erosion of the slope in the Licosa Channel, a high sedimentation rate in the sedimentary wedge, earthquake shaking, the volcanic ash nature of the detachment surface, subsurface gas/fluid migration, and lateral porewater flow from the depocentre of wedge to the base of the slope along the high-permeability ash layers. A newly discovered prominent structural discontinuity is identified as the fault whose activity may have triggered the landslide