2,041 research outputs found
Non-linear photonic crystals as a source of entangled photons
Non-linear photonic crystals can be used to provide phase-matching for
frequency conversion in optically isotropic materials. The phase-matching
mechanism proposed here is a combination of form birefringence and phase
velocity dispersion in a periodic structure. Since the phase-matching relies on
the geometry of the photonic crystal, it becomes possible to use highly
non-linear materials. This is illustrated considering a one-dimensional
periodic AlGaAs / air structure for the generation of 1.5
m light. We show that phase-matching conditions used in schemes to create
entangled photon pairs can be achieved in photonic crystals.Comment: 4 pages, 3 figure
Pitching a business idea to investors: How new venture founders use micro-level rhetoric to achieve narrative plausibility and resonance
For entrepreneurial narratives to be effective, they need to be judged as plausible and have to resonate with an audience. Prior research has, however, not examined or explained how entrepreneurs try to meet these criteria. In this paper, we addressed this question by analysing the micro-level arguments underpinning the pitch narratives of entrepreneurs who joined a business incubator. We discerned four previously unidentified rhetorical strategies that these entrepreneurs used to achieve narrative plausibility and resonance. Our findings further suggest that temporality and product development status may shape how entrepreneurs use these strategies. By outlining these aspects of entrepreneurial rhetoric, we contribute to opening up the black box of narrative resonance and plausibility and advance work on the role of rhetoric in entrepreneurship
Multipartite entanglement of fermionic systems in noninertial frames
The bipartite and tripartite entanglement of a 3-qubit fermionic system when
one or two subsystems accelerated are investigated. It is shown that all the
one-tangles decrease as the acceleration increases. However, unlike the scalar
case, here one-tangles and never
reduce to zero for any acceleration. It is found that the system has only
tripartite entanglement when either one or two subsystems accelerated, which
means that the acceleration doesn't generate bipartite entanglement and doesn't
effect the entanglement structure of the quantum states in this system. It is
of interest to note that the -tangle of the two-observers-accelerated case
decreases much quicker than that of the one-observer-accelerated case and it
reduces to a non-zero minimum in the infinite acceleration limit. Thus we argue
that the qutrit systems are better than qubit systems to perform quantum
information processing tasks in noninertial systems.Comment: 12 pages, 3 figure
Resilience of multi-photon entanglement under losses
We analyze the resilience under photon loss of the bi-partite entanglement
present in multi-photon states produced by parametric down-conversion. The
quantification of the entanglement is made possible by a symmetry of the states
that persists even under polarization-independent losses. We examine the
approach of the states to the set of states with a positive partial transpose
as losses increase, and calculate the relative entropy of entanglement. We find
that some bi-partite distillable entanglement persists for arbitrarily high
losses.Comment: 5 pages, 3 figures, title changed, minor typographic errors correcte
Multiphoton path entanglement by non-local bunching
Multiphoton path entanglement is created without applying post-selection, by
manipulating the state of stimulated parametric down-conversion. A specific
measurement on one of the two output spatial modes leads to the non-local
bunching of the photons of the other mode, forming the desired multiphoton path
entangled state. We present experimental results for the case of a heralded
two-photon path entangled state and show how to extend this scheme to higher
photon numbers.Comment: 4 pages, 5 figures, published versio
Quantum filter for non-local polarization properties of photonic qubits
We present an optical filter that transmits photon pairs only if they share
the same horizontal or vertical polarization, without decreasing the quantum
coherence between these two possibilities. Various applications for
entanglement manipulations and multi-photon qubits are discussed.Comment: 7 pages, including one figure, short discussion of error sources
adde
High-fidelity entanglement swapping with fully independent sources
Entanglement swapping allows to establish entanglement between independent
particles that never interacted nor share any common past. This feature makes
it an integral constituent of quantum repeaters. Here, we demonstrate
entanglement swapping with time-synchronized independent sources with a
fidelity high enough to violate a Clauser-Horne-Shimony-Holt inequality by more
than four standard deviations. The fact that both entangled pairs are created
by fully independent, only electronically connected sources ensures that this
technique is suitable for future long-distance quantum communication
experiments as well as for novel tests on the foundations of quantum physics.Comment: added technical details and extended introduction and conclusion,
slightly modified the abstract, corrected a mistake in the affiliation
Dynamics of Entanglement Transfer Through Multipartite Dissipative Systems
We study the dynamics of entanglement transfer in a system composed of two
initially correlated three-level atoms, each located in a cavity interacting
with its own reservoir. Instead of tracing out reservoir modes to describe the
dynamics using the master equation approach, we consider explicitly the
dynamics of the reservoirs. In this situation, we show that the entanglement is
completely transferred from atoms to reservoirs. Although the cavities mediate
this entanglement transfer, we show that under certain conditions, no
entanglement is found in cavities throughout the dynamics. Considering the
entanglement dynamics of interacting and non-interacting bipartite subsystems,
we found time windows where the entanglement can only flow through interacting
subsystems, depending on the system parameters.Comment: 8 pages, 11 figures, publishe in Physical Review
A posteriori teleportation
The article by Bouwmeester et al. on experimental quantum teleportation
constitutes an important advance in the burgeoning field of quantum
information. The experiment was motivated by the proposal of Bennett et al. in
which an unknown quantum state is `teleported' by Alice to Bob. As illustrated
in Fig. 1, in the implementation of this procedure, by Bouwmeester et al., an
input quantum state is `disembodied' into quantum and classical components, as
in the original protocol. However, in contrast to the original scheme,
Bouwmeester et al.'s procedure necessarily destroys the state at Bob's
receiving terminal, so a `teleported' state can never emerge as a freely
propagating state for subsequent examination or exploitation. In fact,
teleportation is achieved only as a postdiction.Comment: 1 page LaTeX including 1 figure. Scientific Correspondence about:
"Experimental quantum teleportation" Nature 390, 575 (1997
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