12,374 research outputs found
Regularization modeling for large-eddy simulation
A new modeling approach for large-eddy simulation (LES) is obtained by
combining a `regularization principle' with an explicit filter and its
inversion. This regularization approach allows a systematic derivation of the
implied subgrid-model, which resolves the closure problem. The central role of
the filter in LES is fully restored, i.e., both the interpretation of LES
predictions in terms of direct simulation results as well as the corresponding
subgrid closure are specified by the filter. The regularization approach is
illustrated with `Leray-smoothing' of the nonlinear convective terms. In
turbulent mixing the new, implied subgrid model performs favorably compared to
the dynamic eddy-viscosity procedure. The model is robust at arbitrarily high
Reynolds numbers and correctly predicts self-similar turbulent flow
development.Comment: 16 pages, 4 figures, submitted to Physics of Fluid
Broadband quadrature-squeezed vacuum and nonclassical photon number correlations from a nanophotonic device
We report the first demonstrations of both quadrature squeezed vacuum and
photon number difference squeezing generated in an integrated nanophotonic
device. Squeezed light is generated via strongly driven spontaneous four-wave
mixing below threshold in silicon nitride microring resonators. The generated
light is characterized with both homodyne detection and direct measurements of
photon statistics using photon number-resolving transition edge sensors. We
measure ~dB of broadband quadrature squeezing (~dB inferred
on-chip) and ~dB of photon number difference squeezing (~dB
inferred on-chip). Nearly-single temporal mode operation is achieved, with raw
unheralded second-order correlations as high as measured
(~when corrected for noise). Multi-photon events of over 10 photons
are directly detected with rates exceeding any previous quantum optical
demonstration using integrated nanophotonics. These results will have an
enabling impact on scaling continuous variable quantum technology.Comment: Significant improvements and updates to photon number squeezing
results and discussions, including results on single temporal mode operatio
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