445 research outputs found
Emergence of Quantum Correlations from Non-Locality Swapping
By studying generalized non-signalling theories, the hope is to find out what
makes quantum mechanics so special. In the present paper, we revisit the
paradigmatic model of non-signalling boxes and introduce the concept of a
genuine box. This will allow us to present the first generalized non-signalling
model featuring quantum-like dynamics. In particular, we present the coupler, a
device enabling non-locality swapping, the analogue of quantum entanglement
swapping, as well as teleportation. Remarkably, part of the boundary between
quantum and post-quantum correlations emerges in our study.Comment: 5 pages. 6 figures. Minor Revisions. To appear in PR
Dynamics of a two-level system coupled with a quantum oscillator in the very strong coupling limit
The time-dependent behavior of a two-level system interacting with a quantum
oscillator system is analyzed in the case of a coupling larger than both the
energy separation between the two levels and the energy of quantum oscillator
(, where is the frequency of the
transition between the two levels, is the frequency of the
oscillator, and is the coupling between the two-level system and the
oscillator). Our calculations show that the amplitude of the expectation value
of the oscillator coordinate decreases as the two-level system undergoes the
transition from one level to the other, while the transfer probability between
the levels is staircase-like. This behavior is explained by the interplay
between the adiabatic and the non-adiabatic regimes encountered during the
dynamics with the system acting as a quantum counterpart of the Landau-Zener
model. The transition between the two levels occurs as long as the expectation
value of the oscillator coordinate is driven close to zero. On the contrary, if
the initial conditions are set such that the expectation values of the
oscillator coordinate are far from zero, the system will remain locked on one
level.Comment: 4 pages, 4 figures, to be published in Physical Review
Analysis the 1978–2008 crustal and sub-crustal earthquake catalog of Vrancea region
The crustal and sub-crustal seismicity that occurred in the Vrancea area from 1978 to 2008 is investigated. Due to quarry blast contamination, the analysis of the crustal seismicity was restricted to events that occurred between 20 km and 60 km, considering sub-crustal events as all those that occurred at depths larger than 60 km. The completeness magnitude was estimated between 2.3 and 2.5 for the crustal seismicity and between 2.9 and 3.1 for the sub-crustal one. The Gutenberg-Richter b-values show clear differences between crustal and sub-crustal seismicity, with values around 0.9 and 1.3–1.4, respectively. The analysis performed in this study represents a preliminary issue for the seismic hazard assessment of surrounding regions like Moldova, for which the earthquakes generated in Vrancea represent an important threat
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