7,489 research outputs found
Reservoir cross-over in entanglement dynamics
We study the effects of spontaneous emission on the entanglement dynamics of
two qubits interacting with a common Lorentzian structured reservoir. We assume
that the qubits are initially prepared in a Bell-like state. We focus on the
strong coupling regime and study the entanglement dynamics for different
regions of the spontaneous emission decay parameter. This investigation allows
us to explore the cross-over between common and independent reservoirs in
entanglement dynamics
Influence of modal loss on the quantum state generation via cross-Kerr nonlinearity
In this work we investigate an influence of decoherence effects on quantum
states generated as a result of the cross-Kerr nonlinear interaction between
two modes. For Markovian losses (both photon loss and dephasing), a region of
parameters when losses still do not lead to destruction of non-classicality is
identified. We emphasize the difference in impact of losses in the process of
state generation as opposed to those occurring in propagation channel. We show
moreover, that correlated losses in modern realizations of schemes of large
cross-Kerr nonlinearity might lead to enhancement of non-classicality.Comment: To appear in PR
Spin-Mediated Consciousness: Theory, Experimental Studies, Further Development & Related Topics
We postulate that consciousness is intrinsically connected to quantum spin
since the latter is the origin of quantum effects in both Bohm and Hestenes
quantum formulisms and a fundamental quantum process associated with the
structure of space-time. Applying these ideas to the particular structures and
dynamics of the brain, we have developed a detailed model of quantum
consciousness. We have also carried out experiments from the perspective of our
theory to test the possibility of quantum-entangling the quantum entities
inside the brain with those of an external chemical substance. We found that
applying magnetic pulses to the brain when an anaesthetic was placed in between
caused the brain to feel the effect of said anaesthetic as if the test subject
had actually inhaled the same. We further found that drinking water exposed to
magnetic pulses, laser light or microwave when an anaesthetic was placed in
between also causes brain effects in various degrees. Additional experiments
indicate that the said brain effect is indeed the consequence of quantum
entanglement. Recently we have studied non-local effects in simple physics
systems. We have found that the pH value, temperature and gravity of a liquid
in the detecting reservoirs can be non-locally affected through manipulating
another liquid in a remote reservoir quantum-entangled with the former. In
particular, the pH value changes in the same direction as that being
manipulated; the temperature can change against that of local environment; and
the gravity can change against local gravity. We suggest that they are mediated
by quantum entanglement between nuclear and/or electron spins in treated liquid
and discuss the profound implications of these results. This paper now also
includes materials on further development of the theory and related topics.Comment: 92 pages; expanded content; minor corrections; for additional
information, please visit http://quantumbrain.or
Entangling two distant nanocavities via a waveguide
In this paper, we investigate the generation of continuous variable
entanglement between two spatially-separate nanocavities mediated by a coupled
resonator optical waveguide in photonic crystals. By solving the exact dynamics
of the cavity system coupled to the waveguide, the entanglement and purity of
the two-mode cavity state are discussed in detail for the initially separated
squeezing inputs. It is found that the stable and pure entangled state of the
two distant nanocavities can be achieved with the requirement of only a weak
cavity-waveguide coupling when the cavities are resonant with the band center
of the waveguide. The strong couplings between the cavities and the waveguide
lead to the entanglement sudden death and sudden birth. When the frequencies of
the cavities lie outside the band of the waveguide, the waveguide-induced cross
frequency shift between the cavities can optimize the achievable entanglement.
It is also shown that the entanglement can be easily manipulated through the
changes of the cavity frequencies within the waveguide band.Comment: 8 pages, 8 figure
Entanglement generated between a single atom and a laser pulse
We quantify the entanglement generated between an atom and a laser pulse in
free space. We find that the entanglement calculated using a simple
closed-system Jaynes-Cummings Hamiltonian is in remarkable agreement with a
full open-system calculation, even though the free-space geometry is far from
the strong coupling regime of cavity QED. We explain this result using a simple
model in which the atom couples weakly to the laser while coupling strongly to
the vacuum. Additionally we place an upper bound on the total entanglement
between the atom and all paraxial modes using a quantum trajectories
unravelling. This upper bound provides a benchmark for atom-laser coupling.Comment: 8 pages, 4 figure
Decoherence induced by a phase-damping reservoir
A phase damping reservoir composed by -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
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