3,495 research outputs found
Increasing and decreasing entanglement characteristics for continuous variables by a local photon subtraction
We investigate how the entanglement characteristics of a non-Gaussian
entangled state are increased or decreased by a local photon subtraction
operation. The non-Gaussian entangled state is generated by injecting a
single-mode non-Gaussian state and a vacuum state into a 50:50 beam splitter.
We consider a photon-added coherent state and an odd coherent state as a
single-mode non-Gaussian state. In the regime of small amplitude, we show that
the performance of quantum teleportation and the second-order
Einstein-Podolsky- Rosen-type correlation can both be enhanced, whereas the
degree of entanglement decreases, for the output state when a local photon
subtraction operation is applied to the non-Gaussian entangled state. The
counterintuitive effect is more prominent in the limit of nearly zero
amplitude.Comment: Published version, 7 pages, 3 figure
Enhancing quantum entanglement for continuous variables by a coherent superposition of photon subtraction and addition
We investigate how the entanglement properties of a two-mode state can be
improved by performing a coherent superposition operation of photon subtraction
and addition, proposed by Lee and Nha [Phys. Rev. A 82, 053812 (2010)], on each
mode. We show that the degree of entanglement, the EPR-type correlation, and
the performance of quantum teleportation can be all enhanced for the output
state when the coherent operation is applied to a two-mode squeezed state. The
effects of the coherent operation are more prominent than those of the mere
photon subtraction and the addition particularly in the small squeezing regime,
whereas the optimal operation becomes the photon subtraction in the
large-squeezing regime.Comment: 6 pages, 6 figures, published versio
A photonic-crystal optical antenna for extremely large local-field enhancement
We propose a novel design of an all-dielectric optical antenna based on photonic-band-gap confinement. Specifically, we have engineered the photonic-crystal dipole mode to have broad spectral response (Q ~70) and well-directed vertical-radiation by introducing a plane mirror below the cavity. Considerably large local electric-field intensity enhancement ~4,500 is expected from the proposed design for a normally incident planewave. Furthermore, an analytic model developed based on coupled-mode theory predicts that the electric-field intensity enhancement can easily be over 100,000 by employing reasonably high-Q (~10,000) resonators
Two-dimensional heterogeneous photonic bandedge laser
We proposed and realized a two-dimensional (2D) photonic bandedge laser
surrounded by the photonic bandgap. The heterogeneous photonic crystal
structure consists of two triangular lattices of the same lattice constant with
different air hole radii. The photonic crystal laser was realized by
room-temperature optical pumping of air-bridge slabs of InGaAsP quantum wells
emitting at 1.55 micrometer. The lasing mode was identified from its spectral
positions and polarization directions. A low threshold incident pump power of
0.24mW was achieved. The measured characteristics of the photonic crystal
lasers closely agree with the results of real space and Fourier space
calculations based on the finite-difference time-domain method.Comment: 14 pages, 4 figure
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