418 research outputs found
On the effects of self- and cross-phase modulation on photon purity for four-wave mixing photon-pair sources
We consider the effect of self-phase modulation and cross-phase modulation on
the joint spectral amplitude of photon pairs generated by spontaneous four-wave
mixing. In particular, the purity of a heralded photon from a pair is
considered, in the context of schemes that aim to maximise the purity and
minimise correlation in the joint spectral amplitude using birefringent
phase-matching and short pump pulses. We find that non-linear phase modulation
effects will be detrimental, and will limit the quantum interference visibility
that can be achieved at a given generation rate. An approximate expression for
the joint spectral amplitude with phase modulation is found by considering the
group velocity walk-off between each photon and the pump, but neglecting the
group-velocity dispersion at each wavelength. The group-velocity dispersion can
also be included with a numerical calculation, and it is shown that it only has
a small effect on the purity for the realistic parameters considered.Comment: 11 pages, 10 figure
Shape-preserving and unidirectional frequency conversion using four-wave mixing Bragg scattering
In this work, we investigate the properties of four-wave mixing Bragg
scattering in a configuration that employs orthogonally polarized pumps in a
birefringent waveguide. This configuration enables a large signal conversion
bandwidth, and allows strongly unidirectional frequency conversion as undesired
Bragg-scattering processes are suppressed by waveguide birefringence. Moreover,
we show that this form of four-wave mixing Bragg scattering preserves the
(arbitrary) signal pulse shape, even when driven by pulsed pumps.Comment: 11 pages + refs, 5 figure
Fluctuating Hydrodynamics and the Rayleigh-Plateau Instability
The Rayleigh-Plateau instability occurs when surface tension makes a fluid
column become unstable to small perturbations. At nanometer scales, thermal
fluctuations are comparable to surface energy densities. Consequently, at these
scales, thermal fluctuations play a significant role in the dynamics of the
instability. These microscopic effects have previously been investigated
numerically using particle-based simulations, such as molecular dynamics, and
stochastic partial differential equation based hydrodynamic models, such as
stochastic lubrication theory. In this paper we present an incompressible
fluctuating hydrodynamics model with a diffuse-interface formulation for binary
fluid mixtures designed for the study of stochastic interfacial phenomena. An
efficient numerical algorithm is outlined and validated in numerical
simulations of stable equilibrium interfaces. We present results from
simulations of the Rayleigh-Plateau instability for long cylinders pinching
into droplets for Ohnesorge numbers of Oh = 0.5 and 5.0. Both stochastic and
perturbed deterministic simulations are analyzed and ensemble results show
significant differences in the temporal evolution of the minimum radius near
pinching. Short cylinders, with lengths less than their circumference, were
also investigated. As previously observed in molecular dynamics simulations, we
find that thermal fluctuations cause these to pinch in cases where a perturbed
cylinder would be stable deterministically. Finally we show that the
fluctuating hydrodynamics model can be applied to study a broader range of
surface-tension driven phenomena
Nonlinearity-induced spectral lattice with optically tunable long-range complex hopping
We suggest and realize experimentally quantum walks on a spectral photonic lattice with optically tunable long-range and complex hopping coefficients facilitated by nonlinear parametric interactions, enabling asymmetric frequency shaping and Talbot effect with arbitrary periodicity.The authors acknowledge financial support from the Australian Research Council
Intrinsically narrowband pair photon generation in microstructured fibres
In this paper we study the tailoring of photon spectral properties generated
by four-wave mixing in a birefringent photonic crystal fibre (PCF). The aim is
to produce intrinsically narrow-band photons and hence to achieve high
non-classical interference visibility and generate high fidelity entanglement
without any requirement for spectral filtering, leading to high effective
detection efficiencies. We show unfiltered Hong-Ou-Mandel interference
visibilities of 77% between photons from the same PCF, and 80% between separate
sources. We compare results from modelling the PCF to these experiments and
analyse photon purities.Comment: 23 pages, 17 figures, Comments Welcom
Synthetic photonic lattice for single-shot reconstruction of frequency combs
We formulate theoretically and demonstrate experimentally an all-optical
method for reconstruction of the amplitude, phase and coherence of frequency
combs from a single-shot measurement of the spectral intensity. Our approach
exploits synthetic frequency lattices with pump-induced spectral short- and
long-range couplings between different signal components across a broad
bandwidth of of hundreds GHz in a single nonlinear fiber. When combined with
ultra-fast signal conversion techniques, this approach has the potential to
provide real-time measurement of pulse-to-pulse variations in the spectral
phase and coherence properties of exotic light sources.Comment: 15 pages, 4 figure
Multidimensional synthetic chiral-tube lattices via nonlinear frequency conversion
Geometrical dimensionality plays a fundamentally important role in the
topological effects arising in discrete lattices. While direct experiments are
limited by three spatial dimensions, the research topic of synthetic dimensions
implemented by the frequency degree of freedom in photonics is rapidly
advancing. The manipulation of light in such artificial lattices is typically
realized through electro-optic modulation, yet their operating bandwidth
imposes practical constraints on the range of interactions between different
frequency components. Here we propose and experimentally realize all-optical
synthetic dimensions involving specially tailored simultaneous short- and
long-range interactions between discrete spectral lines mediated by frequency
conversion in a nonlinear waveguide. We realize triangular chiral-tube lattices
in three-dimensional space and explore their four-dimensional generalization.
We implement a synthetic gauge field with nonzero magnetic flux and observe the
associated multidimensional dynamics of frequency combs, all within one
physical spatial port. We anticipate that our method will provide a new means
for the fundamental study of high-dimensional physics and act as an important
step towards using topological effects in optical devices operating in the time
and frequency domains.Comment: 20 pages, 6 figure
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