198 research outputs found
Quantum frequency conversion and strong coupling of photonic modes using four-wave mixing in integrated microresonators
Single photon-level quantum frequency conversion has recently been
demonstrated using silicon nitride microring resonators. The resonance
enhancement offered by such systems enables high-efficiency translation of
quantum states of light across wide frequency ranges at sub-watt pump powers.
Using a quantum-mechanical Hamiltonian formalism, we present a detailed
theoretical analysis of the conversion dynamics in these systems, and show that
they are capable of converting single- and multi-photon quantum states.
Analytic formulas for the conversion efficiency, spectral conversion
probability density, and pump power requirements are derived which are in good
agreement with previous theoretical and experimental results. We show that with
only modest improvement to the state of the art, efficiencies exceeding 95% are
achievable using less than 100 mW of pump power. At the critical driving
strength that yields maximum conversion efficiency, the spectral conversion
probability density is shown to exhibit a flat-topped peak, indicating a range
of insensitivity to the spectrum of a single photon input. Two alternate
theoretical approaches are presented to study the conversion dynamics: a
dressed mode approach that yields a better intuitive picture of the conversion
process, and a study of the temporal dynamics of the participating modes in the
resonator, which uncovers a regime of Rabi-like coherent oscillations of single
photons between two different frequency modes. This oscillatory regime arises
from the strong coupling of distinct frequency modes mediated by coherent
pumps.Comment: 14 pages, 7 figure
Scalable squeezed light source for continuous variable quantum sampling
We propose a novel squeezed light source capable of meeting the stringent
requirements of continuous variable quantum sampling. Using the effective
interaction induced by a strong driving beam in the presence of the
response in an integrated microresonator, our device is compatible
with established nanophotonic fabrication platforms. With typical realistic
parameters, squeezed states with a mean photon number of 10 or higher can be
generated in a single consistent temporal mode at repetition rates in excess of
100MHz. Over 15dB of squeezing is achievable in existing ultra-low loss
platforms
Stimulated Emission Tomography: Beyond Polarization
In this work we demonstrate the use of stimulated emission tomography to
characterize a hyper-entangled state generated by spontaneous parametric
down-conversion in a CW-pumped source. In particular, we consider the
generation of hyper-entangled states consisting of photon pairs entangled in
polarisation and path. These results extend the capability of stimulated
emission tomography beyond the polarisation degree of freedom, and demonstrate
the use of this technique to study states in higher dimension Hilbert spaces
Tailoring second-harmonic generation in birefringent poled fiber via Twist
We predict theoretically and demonstrate experimentally the ability to generate and control the strengths of various second-harmonic signals in birefringent poled fiber. This is done by simply twisting the fiber
Nonlinear Coupling of Linearly Uncoupled Resonators
We demonstrate a system composed of two resonators that are coupled solely
through a nonlinear interaction, and where the linear properties of each
resonator can be controlled locally. We show that this class of dynamical
systems has peculiar properties with important consequences for the study of
classical and quantum nonlinear optical phenomena. As an example we discuss the
case of dual-pump spontaneous four-wave mixing.Comment: 4 Figure
Truly unentangled photon pairs without spectral filtering
We demonstrate that an integrated silicon microring resonator is capable of
efficiently producing photon pairs that are completely unentangled; such pairs
are a key component of heralded single photon sources. A dual-channel
interferometric coupling scheme can be used to independently tune the quality
factors associated with the pump and signal and idler modes, yielding a
biphoton wavefunction with Schmidt number arbitrarily close to unity. This will
permit the generation of heralded single photon states with unit purity.Comment: 5 pages, 3 figure
Integrated sources of photon quantum states based on nonlinear optics
The ability to generate complex optical photon states involving entanglement between multiple optical modes is not only critical to advancing our understanding of quantum mechanics but will play a key role in generating many applications in quantum technologies. These include quantum communications, computation, imaging, microscopy and many other novel technologies that are constantly being proposed. However, approaches to generating parallel multiple, customisable bi- and multi-entangled quantum bits (qubits) on a chip are still in the early stages of development. Here, we review recent advances in the realisation of integrated sources of photonic quantum states, focusing on approaches based on nonlinear optics that are compatible with contemporary optical fibre telecommunications and quantum memory platforms as well as with chip-scale semiconductor technology. These new and exciting platforms hold the promise of compact, low-cost, scalable and practical implementations of sources for the generation and manipulation of complex quantum optical states on a chip, which will play a major role in bringing quantum technologies out of the laboratory and into the real world
Broadband polarization-entanglement in a poled fiber
Broadband polarization-entanglement over 100 nm is demonstrated in a poled fiber phase-matched for type-II downconversion in the 1.5µm telecom-band. Two-photon interference and Hong-Ou-Mandel interference are used experimentally to confirm the broadband nature of the entanglement
Characterizing an Entangled-Photon Source with Classical Detectors and Measurements
Quantum state tomography (QST) is a universal tool for the design and
optimization of entangled-photon sources. It typically requires single-photon
detectors and coincidence measurements. Recently, it was suggested that the
information provided by the QST of photon pairs generated by spontaneous
parametric down-conversion could be obtained by exploiting the stimulated
version of this process, namely difference frequency generation. In this
protocol, so-called "stimulated-emission tomography" (SET), a seed field is
injected along with the pump pulse, and the resulting stimulated emission is
measured. Since the intensity of the stimulated field can be several orders of
magnitude larger than the intensity of the corresponding spontaneous emission,
measurements can be made with simple classical detectors. Here, we
experimentally demonstrate SET and compare it with QST. We show that one can
accurately reconstruct the polarization density matrix, and predict the purity
and concurrence of the polarization state of photon pairs without performing
any single-photon measurements.Comment: 5+3 pages, 5 figures, 1 tabl
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