4,935 research outputs found
Why you should not use the electric field to quantize in nonlinear optics
We show that using the electric field as a quantization variable in nonlinear
optics leads to incorrect expressions for the squeezing parameters in
spontaneous parametric down-conversion and conversion rates in frequency
conversion. This observation is related to the fact that if the electric field
is written as a linear combination of bosonic creation and annihilation
operators one cannot satisfy Maxwell's equations in a nonlinear dielectric.Comment: This version corrects a minor typo from the published version in
Optics Letters. Eq. 22 should have an \epsilon_0 that is lacking in the OL
versio
High efficiency in mode selective frequency conversion
Frequency conversion (FC) is an enabling process in many quantum information
protocols. Recently, it has been observed that upconversion efficiencies in
single-photon, mode-selective FC are limited to around 80%.In this letter we
argue that these limits can be understood as time-ordering corrections (TOCs)
that modify the joint conversion amplitude of the process. Furthermore we show,
using a simple scaling argument, that recently proposed cascaded FC protocols
that overcome the aforementioned limitations act as "attenuators" of the TOCs.
This observation allows us to argue that very similar cascaded architectures
can be used to attenuate TOCs in photon generation via spontaneous parametric
down-conversion. Finally, by using the Magnus expansion, we argue that the
TOCs, which are usually considered detrimental for FC efficiency, can also be
used to increase the efficiency of conversion in partially mode selective FC
Dispersive spherical optical model of neutron scattering from Al27 up to 250 MeV
A spherical optical model potential (OMP) containing a dispersive term is
used to fit the available experimental database of angular distribution and
total cross section data for n + Al27 covering the energy range 0.1- 250 MeV
using relativistic kinematics and a relativistic extension of the Schroedinger
equation. A dispersive OMP with parameters that show a smooth energy dependence
and energy independent geometry are determined from fits to the entire data
set. A very good overall agreement between experimental data and predictions is
achieved up to 150 MeV. Inclusion of nonlocality effects in the absorptive
volume potential allows to achieve an excellent agreement up to 250 MeV.Comment: 13 figures (11 eps and 2 jpg), 3 table
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