3,595 research outputs found
Continuous variable entanglement enhancement and manipulation by a sub-threshold type-II optical parametric amplifier
We experimentally demonstrate that the quantum entanglement between amplitude
and phase quadratures of optical modes produced from a non-degenerate optical
parametric amplifier (NOPA) can be enhanced and manipulated phase-sensitively
by means of another NOPA. When both NOPAs operate at de-amplification, the
entanglement degree is increased at the cavity resonance of the second NOPA.
When the first NOPA operates at de-amplification and the second one at
amplification, the spectral features of the correlation variances are
significantly changed. The experimental results are in good agreement with the
theoretical expectation
Sub-10 fs pulses tunable from 480 to 980 nm from a NOPA pumped by a Yb:KGW source
We describe two noncollinear optical parametric amplifier (NOPA) systems
pumped by either the second (515 nm) or the third (343 nm) harmonic of an
Yb:KGW amplifier, respectively. Pulse durations as short as 6.8 fs are readily
obtained by compression with commercially available chirped mirrors. The
availability of both second and third harmonic for NOPA pumping allows for
gap-free tuning from 520 to 980 nm. The use of an intermediate NOPA to generate
seed light at 780 nm extends the tuning range of the third-harmonic pumped NOPA
towards 450 nm
Experimental generation of 6 dB continuous variable entanglement from a nondegenerate optical parametric amplifier
We experimentally demonstrated that the quantum correlations of amplitude and
phase quadratures between signal and idler beams produced from a non-degenerate
optical parametric amplifier (NOPA) can be significantly improved by using a
mode cleaner in the pump field and reducing the phase fluctuations in phase
locking systems. Based on the two technical improvements the quantum
entanglement measured with a two-mode homodyne detector is enhanced from ~ 4 dB
to ~ 6 dB below the quantum noise limit using the same NOPA and nonlinear
crystal.Comment: 7 pages, 5 figure
Cascaded Entanglement Enhancement
We present a cascaded system consisting of three non-degenerate optical
parametric amplifiers (NOPAs) for the generation and the enhancement of quantum
entanglement of continuous variables. The entanglement of optical fields
produced by the first NOPA is successively enhanced by the second and the third
NOPAs from -5.3 to -8.1 below the quantum noise limit. The dependence
of the enhanced entanglement on the physical parameters of the NOPAs and the
reachable entanglement limitation for a given cascaded NOPA system are
calculated. The calculation results are in good agreement with the experimental
measurements.Comment: 5 pages, 4 figure
Algorithm Portfolios for Noisy Optimization
Noisy optimization is the optimization of objective functions corrupted by
noise. A portfolio of solvers is a set of solvers equipped with an algorithm
selection tool for distributing the computational power among them. Portfolios
are widely and successfully used in combinatorial optimization. In this work,
we study portfolios of noisy optimization solvers. We obtain mathematically
proved performance (in the sense that the portfolio performs nearly as well as
the best of its solvers) by an ad hoc portfolio algorithm dedicated to noisy
optimization. A somehow surprising result is that it is better to compare
solvers with some lag, i.e., propose the current recommendation of best solver
based on their performance earlier in the run. An additional finding is a
principled method for distributing the computational power among solvers in the
portfolio.Comment: in Annals of Mathematics and Artificial Intelligence, Springer
Verlag, 201
Nonlocality of the Einstein-Podolsky-Rosen state in the phase space
We discuss violation of Bell inequalities by the regularized
Einstein-Podolsky-Rosen (EPR) state, which can be produced in a quantum optical
parametric down-conversion process. We propose an experimental photodetection
scheme to probe nonlocal quantum correlations exhibited by this state.
Furthermore, we show that the correlation functions measured in two versions of
the experiment are given directly by the Wigner function and the Q function of
the EPR state. Thus, the measurement of these two quasidistribution functions
yields a novel scheme for testing quantum nonlocality.Comment: 10 pages LaTeX, contribution to proceedings of 6th central-european
workshop on quantum optic
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