5,838 research outputs found
|0>|1>+|1>|0>
I give a simple argument that demonstrates that the state |0>|1>+|1>|0>, with
|0> denoting a state with 0 particles and |1> a 1-particle state, is entangled
in spite of recent claims to the contrary. I also discuss new viewpoints on the
old controversy about whether the above state can be said to display
single-particle or single-photon nonlocality.Comment: A more serious version, almost 2.36 pages, but still an unnormalized
titl
Composite oscillator systems for meeting user needs for time and frequency
Frequency standards are used in most navigation and telecommunications systems to provide a long term memory of either frequency, phase, or time epoch. From a systems point of view, the performance aspects of the frequency standard are weighed against other systems characteristics, such as overall performance, cost, size, and accessibility; a number of examples are very briefly reviewed. The theory of phase lock and frequency lock systems is outlined in sufficient detail that total oscillator system performance can be predicted from measurements on the individual components. As an example, details of the performance of a high spectral purity oscillator phase locked to a long term stable oscillator are given. Results for several systems, including the best system stability that can be obtained from present commercially available 5-MHz sources, are shown
The Electromagnetically Induced Transparency in Mechanical Effects of Light
We consider the dynamical behavior of a nanomechanical mirror in a
high-quality cavity under the action of a coupling laser and a probe laser. We
demonstrate the existence of the analog of electromagnetically induced
transparency (EIT) in the output field at the probe frequency. Our calculations
show explicitly the origin of EIT-like dips as well as the characteristic
changes in dispersion from anomalous to normal in the range where EIT dips
occur. Remarkably the pump-probe response for the opto mechanical system shares
all the features of the Lambda system as discovered by Harris and
collaborators.Comment: 4 pages, 5 figure
Electromagnetically Induced Transparency from Two Phonon Processes in Quadratically Coupled Membranes
We describe how electromagnetically induced transparency can arise in
quadratically coupled optomechanical systems. Due to quadratic coupling the
underlying optical process involves a two phonon process in optomechanical
system and this two phonon process makes the mean amplitude, which plays the
role of atomic coherence in traditional EIT, zero. We show how the fluctuation
in displacement can play a role similar to atomic coherence and can lead to
EIT-like effects in quadratically coupled optomechanical systems. We show how
such effects can be studied using the existing optomechanical systems.Comment: 5 pages,4 figure
Can reactive coupling beat motional quantum limit of nano waveguides coupled to microdisk resonator
Dissipation is generally thought to affect the quantum nature of the system
in an adverse manner, however we show that dissipatively coupled nano systems
can be prepared in states which beat the standard quantum limit of the
mechanical motion. We show that the reactive coupling between the waveguide and
the microdisk resonator can generate the squeezing of the waveguide by
injecting a quantum field and laser into the resonator through the waveguide.
The waveguide can show about 70--75% of maximal squeezing for temperature about
1--10 mK. The maximum squeezing can be achieved with incident pump power of
only 12 W for a temperature of about 1 mK. Even for temperatures of 20 mK,
achievable by dilution refrigerators, the maximum squeezing is about 60%.Comment: 6 pages,2 figure
To outsource or not to outsource!
In this article we will take a look at the phenomena of outsourcing as an overarching business concept that is, in short, about contracting of a specific bit of our business to a third part organisation. Consequently, outsourcing is a natural part of the make, share or buy continuum, as illustrated in Figure 1. We would, therefore, argue that outsourcing is not a new business phenomena as it has been commonly practiced since the early times of industrialisation, even though recently it has been enjoying renewed attention fuelled by the globalising forces
Intelligent process development of foam molding for the Thermal Protection System (TPS) of the space shuttle external tank
A knowledge based system to assist process engineers in evaluating the processability and moldability of poly-isocyanurate (PIR) formulations for the thermal protection system of the Space Shuttle external tank (ET) is discussed. The Reaction Injection Molding- Process Development Advisor (RIM-PDA) is a coupled system which takes advantage of both symbolic and numeric processing techniques. This system will aid the process engineer in identifying a startup set of mold schedules and in refining the mold schedules to remedy specific process problems diagnosed by the system
Realistic continuous-variable quantum teleportation with non-Gaussian resources
We present a comprehensive investigation of nonideal continuous-variable
quantum teleportation implemented with entangled non-Gaussian resources. We
discuss in a unified framework the main decoherence mechanisms, including
imperfect Bell measurements and propagation of optical fields in lossy fibers,
applying the formalism of the characteristic function. By exploiting
appropriate displacement strategies, we compute analytically the success
probability of teleportation for input coherent states, and two classes of
non-Gaussian entangled resources: Two-mode squeezed Bell-like states (that
include as particular cases photon-added and photon-subtracted de-Gaussified
states), and two-mode squeezed cat-like states. We discuss the optimization
procedure on the free parameters of the non-Gaussian resources at fixed values
of the squeezing and of the experimental quantities determining the
inefficiencies of the non-ideal protocol. It is found that non-Gaussian
resources enhance significantly the efficiency of teleportation and are more
robust against decoherence than the corresponding Gaussian ones. Partial
information on the alphabet of input states allows further significant
improvement in the performance of the non-ideal teleportation protocol.Comment: 14 pages, 6 figure
Quantum decoherence reduction by increasing the thermal bath temperature
The well-known increase of the decoherence rate with the temperature, for a
quantum system coupled to a linear thermal bath, holds no longer for a
different bath dynamics. This is shown by means of a simple classical
non-linear bath, as well as a quantum spin-boson model. The anomalous effect is
due to the temperature dependence of the bath spectral profile. The decoherence
reduction via the temperature increase can be relevant for the design of
quantum computers
Models of Poverty and Planned Change: A Framework for Synthesis
Recent discussions of planned social change have organized interventive strategies into models which identify underlying philosophical assumptions, value orientations, and political perspectives. Two papers published in 1965 can be taken as the beginning of this model-building discussion: Richard Walton proposed a dichotomy between attitude change and power strategies, and Roland Warren outlined a continuum from collaborative through campaign to contest strategies. In the subsequent literature, three publications stand out as major formulations of models of planned social change. What is particularly striking is that each develops a trichotomous typology of change strategies. Jack Rothman (1968) formulates the Locality Development, Social Planning, and Social Action models; Robert Chin and Kenneth Benne (1969) formulate the Rational-Empirical, Normative/Re-Educative, and Power- Coercive models; and James Crowfoot and Mark Chesler (1974) formulate the Countercultural, Professional-Technical, and Political model
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