51,746 research outputs found
A stationary free boundary problem modeling electrostatic MEMS
A free boundary problem describing small deformations in a membrane based
model of electrostatically actuated MEMS is investigated. The existence of
stationary solutions is established for small voltage values. A justification
of the widely studied narrow-gap model is given by showing that steady state
solutions of the free boundary problem converge toward stationary solutions of
the narrow-gap model when the aspect ratio of the device tends to zero
Projection Measurement of the Maximally Entangled N-Photon State for a Demonstration of N-Photon de Broglie Wavelength
We construct a projection measurement process for the maximally entangled
N-photon state (the NOON-state) with only linear optical elements and
photodetectors. This measurement process will give null result for any N-photon
state that is orthogonal to the NOON state. We examine the projection process
in more detail for N=4 by applying it to a four-photon state from type-II
parametric down-conversion. This demonstrates an orthogonal projection
measurement with a null result. This null result corresponds to a dip in a
generalized Hong-Ou-Mandel interferometer for four photons. We find that the
depth of the dip in this arrangement can be used to distinguish a genuine
entangled four-photon state from two separate pairs of photons. We next apply
the NOON state projection measurement to a four-photon superposition state from
two perpendicularly oriented type-I parametric down-conversion processes. A
successful NOON state projection is demonstrated with the appearance of the
four-photon de Broglie wavelength in the interference fringe pattern.Comment: 8 pages, 3 figures, new title, some content change, replaced Fig.
Entanglement detection beyond the CCNR criterion for infinite-dimensions
In this paper, in terms of the relation between the state and the reduced
states of it, we obtain two inequalities which are valid for all separable
states in infinite-dimensional bipartite quantum systems. One of them provides
an entanglement criterion which is strictly stronger than the computable
cross-norm or realignment (CCNR) criterion.Comment: 11 page
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