4,605 research outputs found
Unified entropic measures of quantum correlations induced by local measurements
We introduce quantum correlations measures based on the minimal change in
unified entropies induced by local rank-one projective measurements, divided by
a factor that depends on the generalized purity of the system in the case of
non-additive entropies. In this way, we overcome the issue of the artificial
increasing of the value of quantum correlations measures based on non-additive
entropies when an uncorrelated ancilla is appended to the system without
changing the computability of our entropic correlations measures with respect
to the previous ones. Moreover, we recover as limiting cases the quantum
correlations measures based on von Neumann and R\'enyi entropies (i.e.,
additive entropies), for which the adjustment factor becomes trivial. In
addition, we distinguish between total and semiquantum correlations and obtain
some relations between them. Finally, we obtain analytical expressions of the
entropic correlations measures for typical quantum bipartite systems.Comment: 10 pages, 1 figur
Dynamics of Entanglement and Bell-nonlocality for Two Stochastic Qubits with Dipole-Dipole Interaction
We have studied the analytical dynamics of Bell nonlocality as measured by
CHSH inequality and entanglement as measured by concurrence for two noisy
qubits that have dipole-dipole interaction. The nonlocal entanglement created
by the dipole-dipole interaction is found to be protected from sudden death for
certain initial states
Geochemistry and mineralogy of travertine deposits of the SW flank of Mt. Etna (Italy): Relationships with past volcanic and degassing activity
Travertine deposits outcropping in the lower SW flank of Mt. Etna were studied for their mapping, as well as for their chemical,
mineralogical and isotopic compositions. These deposits are dated to about 24 to 5 ka in the Adrano area, located at the western
limit of the study area. In this area travertines show high Mg contents and are composed mostly of dolomite, thus apparently ruling
out any primary deposition in favour of a diagenetic origin. Travertines outcropping near Paternò, in the east part of the study area,
should be younger than 18 ka. Those located to the SSW of Paternò (Paternò–Diga) show high Sr contents and aragonite as
dominant mineralogical phase, thus suggesting primary deposition. Those located to the Wof Paternò (Paternò Simeto–Stazione)
are instead poor both in Mg and in Sr and show calcite as dominant phase. Carbon isotope composition of travertines indicates a
magmatic origin of CO2 that formed them. Based on the estimated volume of travertines, between 10 and 20 Gg/a of CO2 were
involved in their formation. The time-span of travertine formation coincided with the eruptive cycles of Ellittico and the first part of
Mongibello, which were probably characterised by a greater amount of CO2 transported through groundwater circulation.
Widespread travertine deposition probably ceased after the opening of the Valle del Bove depression that modified the volcanologic
and hydrologic conditions in the summit crater area
Entanglement dynamics of two independent qubits in environments with and without memory
A procedure to obtain the dynamics of independent qudits (-level
systems) each interacting with its own reservoir, for any arbitrary initial
state, is presented. This is then applied to study the dynamics of the
entanglement of two qubits, initially in an extended Werner-like mixed state
with each of them in a zero temperature non-Markovian environment. The
dependence of the entanglement dynamics on the purity and degree of
entanglement of the initial states and on the amount of non-Markovianity is
also given. This extends the previous work about non-Markovian effects on the
two-qubit entanglement dynamics for initial Bell-like states [B. Bellomo
\textit{et al.}, Phys. Rev. Lett. \textbf{99}, 160502 (2007)]. The effect of
temperature on the two-qubit entanglement dynamics in a Markovian environment
is finally obtained.Comment: 10 pages, 6 figure
Entanglement Trapping in Structured Environments
The entanglement dynamics of two independent qubits each embedded in a
structured environment under conditions of inhibition of spontaneous emission
is analyzed, showing entanglement trapping. We demonstrate that entanglement
trapping can be used efficiently to prevent entanglement sudden death. For the
case of realistic photonic band-gap materials, we show that high values of
entanglement trapping can be achieved. This result is of both fundamental and
applicative interest since it provides a physical situation where the
entanglement can be preserved and manipulated, e.g. by Stark-shifting the qubit
transition frequency outside and inside the gap.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Lett. on Friday 16 May
200
Elevated trace metals and REE contents in the CO2-rich groundwaters of Florina (N. Greece) a natural analogue of carbon storage systems
The Florina basin, being the main commercial source of CO2 in Greece, represents a good natural analogue for the study of the impact of geologic carbon storage. It is part of a NNW-SSE trending graben filled with ~600 m Plio-Pleistocene fluvial and lacustrine deposits. The area is characterized by the upflow of great quantities of geogenic CO2 probably associated to presently extinct Quaternary volcanic activity. The gas originates mainly from crustal sources but has also a minor (~10%) mantle contribution. This strong upflow of nearly pure CO2 can be recognized in industrially exploitable gas reservoirs, high pCO2 shallow groundwaters and surface gas manifestations. But the increased CO2 content has a deleterious impact on groundwater quality. Due to the increased aggressiveness of the low-pH CO2-rich waters with respect to the aquifer rocks, EU drinking water limits are exceed for many parameters (e.g. Electric conductivity, pH, Na+, SO42-, F-, Al, B, Ba, Fe, Mn and Ni). Considering the additional impact of widespread agricultural activities, which is recognizable in sometimes elevated NO3- contents, only few of the sampled waters (4 out of 40) could be used for potable purposes.
Aquifer waters are also characterized by high REE contents with ΣREE up to ~12 µg/l. Shale-normalized profiles show positive La and Y anomalies and Ce negative anomalies probably indicating a main derivation from iron oxyhydroxide dissolution. The positive Eu anomaly evidences also carbonate dissolution while the enrichment in HREE is probably due to the abundant presence of HCO3-, which increases HREE solubility through complexation.
Future developments of carbon capture and storage programs in the nearby sedimentary basin of Ptolemais and Servia have to carefully take in account the possible deterioration of their groundwater resources due to CO2 leaks from the storage reservoirs
Dynamics of quantum correlations in two-qubit systems within non-Markovian environments
Knowledge of the dynamical behavior of correlations with no classical
counterpart, like entanglement, nonlocal correlations and quantum discord, in
open quantum systems is of primary interest because of the possibility to
exploit these correlations for quantum information tasks. Here we review some
of the most recent results on the dynamics of correlations in bipartite systems
embedded in non-Markovian environments that, with their memory effects,
influence in a relevant way the system dynamics and appear to be more
fundamental than the Markovian ones for practical purposes. Firstly, we review
the phenomenon of entanglement revivals in a two-qubit system for both
independent environments and a common environment. We then consider the
dynamics of quantum discord in non-Markovian dephasing channel and briefly
discuss the occurrence of revivals of quantum correlations in classical
environments.Comment: 20 pages, 4 figures. Review article, in press in Int. J. Mod. Phys.
B, special issue "Classical Vs Quantum correlations in composite systems",
edited by L. Amico, S. Bose, V. Korepin and V. Vedra
Entanglement Dynamics of Two Independent Cavity-Embedded Quantum Dots
We investigate the dynamical behavior of entanglement in a system made by two
solid-state emitters, as two quantum dots, embedded in two separated
micro-cavities. In these solid-state systems, in addition to the coupling with
the cavity mode, the emitter is coupled to a continuum of leaky modes providing
additional losses and it is also subject to a phonon-induced pure dephasing
mechanism. We model this physical configuration as a multipartite system
composed by two independent parts each containing a qubit embedded in a
single-mode cavity, exposed to cavity losses, spontaneous emission and pure
dephasing. We study the time evolution of entanglement of this multipartite
open system finally applying this theoretical framework to the case of
currently available solid-state quantum dots in micro-cavities.Comment: 10 pages, 4 figures, to appear in Topical Issue of Physica Scripta on
proceedings of CEWQO 201
Energy Dissipation Burst on the Traffic Congestion
We introduce an energy dissipation model for traffic flow based on the
optimal velocity model (OV model). In this model, vehicles are defined as
moving under the rule of the OV model, and energy dissipation rate is defined
as the product of the velocity of a vehicle and resistant force which works to
it.Comment: 15 pages, 19 Postscript figures. Reason for replacing: This is the
submitted for
- …