13,610 research outputs found
Frequency Multiplexing for Quasi-Deterministic Heralded Single-Photon Sources
Single-photon sources based on optical parametric processes have been used
extensively for quantum information applications due to their flexibility,
room-temperature operation and potential for photonic integration. However, the
intrinsically probabilistic nature of these sources is a major limitation for
realizing large-scale quantum networks. Active feedforward switching of photons
from multiple probabilistic sources is a promising approach that can be used to
build a deterministic source. However, previous implementations of this
approach that utilize spatial and/or temporal multiplexing suffer from rapidly
increasing switching losses when scaled to a large number of modes. Here, we
break this limitation via frequency multiplexing in which the switching losses
remain fixed irrespective of the number of modes. We use the third-order
nonlinear process of Bragg scattering four-wave mixing as an efficient
ultra-low noise frequency switch and demonstrate multiplexing of three
frequency modes. We achieve a record generation rate of
multiplexed photons per second with an ultra-low = 0.07, indicating
high single-photon purity. Our scalable, all-fiber multiplexing system has a
total loss of just 1.3 dB independent of the number of multiplexed modes, such
that the 4.8 dB enhancement from multiplexing three frequency modes markedly
overcomes switching loss. Our approach offers a highly promising path to
creating a deterministic photon source that can be integrated on a chip-based
platform.Comment: 28 pages, 9 figures. Comments welcom
BER performance analysis of 100 and 200 Gbit/s all-optical OTDM node using symmetric Mach-Zehnder switches
New insight to the feasibility of all-optical ultra speed switching up to 200 Gb/s. The technique will reduce the dependency and bottleneck on the electronic-to-optical-to-electronic conversion. Current conversion speed is up to 40 Gb/s in laboratories. The novel clock extraction technique proposed shows the potential of an all-optical switch. The research results are directly relevant to the access technology where optical fibre and RF is competing to be the solution. The growing demands of bandwidth will exceed RF capability while the optical fibre will be the optimum solution. A PhD project (Le-Minh) funded by the University Studentship, completed in 2007
Temporally and spectrally multiplexed single photon source using quantum feedback control for scalable photonic quantum technologies
Current proposals for scalable photonic quantum technologies require
on-demand sources of indistinguishable single photons with very high efficiency
(having unheralded loss below ). Even with recent progress in the field
there is still a significant gap between the requirements and state of the art
performance. Here, we propose an on-chip source of multiplexed, heralded
photons. Using quantum feedback control on a photon storage cavity with an
optimized driving protocol, we estimate an on-demand efficiency of and
unheralded loss of order , assuming high efficiency detectors and
intrinsic cavity quality factors of order . We further explain how
temporal- and frequency-multiplexing can be used in parallel to significantly
reduce device requirements if single photon frequency conversion is possible
with efficiency in the same range of
High-speed, solid state, interferometric interrogator and multiplexer for fiber Bragg grating sensors
We report on the design and prototyping of a robust high-speed interferometric multiplexer and interrogator for fiber Bragg grating sensors. The scheme is based on the combination of active WDM channel switching and passive, instantaneous interferometry, allowing the resolution of virgin interferometric interrogators to be retained at MHz multiplexing rates. In this article the system design and operation are described, and a prototype scheme is characterized for three sensors and a multiplexing rate of 4 kHz, demonstrating a noise floor of 10 nΔ/âHz and no cross-sensitivity. It is proposed that the system will be applicable to demanding monitoring applications requiring high speed and high resolution measurements across the sensor array
Effect of Loss on Multiplexed Single-Photon Sources
An on-demand single-photon source is a key requirement for scaling many
optical quantum technologies. A promising approach to realize an on-demand
single-photon source is to multiplex an array of heralded single-photon sources
using an active optical switching network. However, the performance of
multiplexed sources is degraded by photon loss in the optical components and
the non-unit detection efficiency of the heralding detectors. We provide a
theoretical description of a general multiplexed single-photon source with
lossy components and derive expressions for the output probabilities of
single-photon emission and multi-photon contamination. We apply these
expressions to three specific multiplexing source architectures and consider
their tradeoffs in design and performance. To assess the effect of lossy
components on near- and long-term experimental goals, we simulate the
multiplexed sources when used for many-photon state generation under various
amounts of component loss. We find that with a multiplexed source composed of
switches with ~0.2-0.4 dB loss and high efficiency number-resolving detectors,
a single-photon source capable of efficiently producing 20-40 photon states
with low multi-photon contamination is possible, offering the possibility of
unlocking new classes of experiments and technologies.Comment: Journal versio
Ultrafast wavelength jumping and wavelength adjustment with low current using monolithically integrated FML for long-reach UDWDM-PON
Ultrafast wavelength jumping at optical network units (ONUs) for an access network with frequency modulated lasers (FMLs) is demonstrated. This FML consists of an intracavity tunable phase section and filtering gain section. It provides a total of 4.2 nm tuning range with fast wavelength jumping (2.2 nm in 1 ”s) and fast adjustment (1.3 nm in 1.8 ns), providing a candidate for the fast tuning ONU for coherent ultradense wavelength-division multiplexing passive optical networks (WDM-PONs).Peer ReviewedPostprint (author's final draft
Active Temporal Multiplexing of Photons
Photonic qubits constitute a leading platform to disruptive quantum
technologies due to their unique low-noise properties. The cost of the photonic
approach is the non-deterministic nature of many of the processes, including
single-photon generation, which arises from parametric sources and negligible
interaction between photons. Active temporal multiplexing - repeating a
generation process in time and rerouting to single modes using an optical
switching network - is a promising approach to overcome this challenge and will
likely be essential for large-scale applications with greatly reduced resource
complexity and system sizes. Requirements include the precise synchronization
of a system of low-loss switches, delay lines, fast photon detectors, and
feed-forward. Here we demonstrate temporal multiplexing of 8 'bins' from a
double-passed heralded photon source and observe an increase in the heralding
and heralded photon rates. This system points the way to harnessing temporal
multiplexing in quantum technologies, from single-photon sources to large-scale
computation.Comment: Minor revision
Development of a dc-ac power conditioner for wind generator by using neural network
This project present of development single phase DC-AC converter for wind
generator application. The mathematical model of the wind generator and Artificial
Neural Network control for DC-AC converter is derived. The controller is designed to
stabilize the output voltage of DC-AC converter. To verify the effectiveness of the
proposal controller, both simulation and experimental are developed. The simulation and
experimental result show that the amplitude of output voltage of the DC-AC converter
can be controlled
Electronic and photonic switching in the atm era
Broadband networks require high-capacity switches in order to properly manage large amounts of traffic fluxes. Electronic and photonic technologies are being used to achieve this objective both allowing different multiplexing and switching techniques. Focusing on the asynchronous transfer mode (ATM), the inherent different characteristics of electronics and photonics makes different architectures feasible. In this paper, different switching structures are described, several ATM switching architectures which have been recently implemented are presented and the implementation characteristics discussed. Three diverse points of view are given from the electronic research, the photonic research and the commercial switches. Although all the architectures where successfully tested, they should also follow different market requirements in order to be commercialised. The characteristics are presented and the architectures projected over them to evaluate their commercial capabilities.Peer ReviewedPostprint (published version
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