99 research outputs found
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
Heralding two- and four-photon path entanglement on chip
Generating quantum entanglement is not only an important scientific endeavor,
but will be essential to realizing quantum-enhanced technologies, in
particular, quantum-enhanced measurements with precision beyond classical
limits. We investigate the heralded generation of multiphoton entanglement for
quantum metrology using a reconfigurable integrated waveguide device in which
projective measurement of auxiliary photons heralds the generation of
path-entangled states. We use four and six-photon inputs, to analyze the
heralding process of two- and four-photon NOON states-a superposition of N
photons in two paths, capable of enabling phase supersensitive measurements at
the Heisenberg limit. Realistic devices will include imperfections; as part of
the heralded state preparation, we demonstrate phase superresolution within our
chip with a state that is more robust to photon loss
Mars 1994/1996: The French navigation tasks
In the fall of 1994, Russia will launch a spacecraft to Mars. France is involved in many scientific experiments which are onboard the spacecraft, as PI or CI. Some days before the Mars orbit insertion maneuver, two small stations and two penetrators will be injected into an entry trajectory. They will carry out for at least six months in situ analysis on the Martian surface. Two years later, a second spacecraft will be launched. It will carry the French balloon and a small rover. The scientific data of these landers will be relayed to earth via the spacecraft. However, during the first 20 days of their mission, Mars Observer will be used. To this end, a Mars balloon relay will be used, which will receive the data from the landers and store them into the memory of the Mars Observer camera. The spacecraft will also be used to localize the landers with the help of relative one-way Doppler measurements. An international cooperative is set up for this process, including JPS, Russian ballistic centers (Babakine, Institute of Applied Mathematics, Moscow Flight Control Center), and CNES Toulouse. Another task dedicated to the space mathematics division of CNES is to support the French scientists to prepare their telecommands and to analyze their telemetry. This second part is integrated into the French ground segment created for the Mars 94/96 mission. This paper describes the method used in CNES for the localization process, the support provided to the scientists, and the links for the data exchange
Photon pair generation in hydrogenated amorphous silicon microring resonators
We generate photon pairs in a-Si:H microrings using a CW pump, and find the
Kerr coefficient of a-Si:H to be . By
measuring the Q factor with coupled power we find that the loss in the a-Si:H
micro-rings scales linearly with power, and therefore cannot originate from two
photon absorption. Theoretically comparing a-Si:H and c-Si micro-ring pair
sources, we show that the high Kerr coefficient of this sample of a-Si:H is
best utilized for microrings with Q factors below , but that for higher Q
factor devices the photon pair rate is greatly suppressed due to the first
order loss.Comment: 10 pages, 5 figure
Fast path and polarisation manipulation of telecom wavelength single photons in lithium niobate waveguide devices
We demonstrate fast polarisation and path control of photons at 1550 nm in
lithium niobate waveguide devices using the electro-optic effect. We show
heralded single photon state engineering, quantum interference, fast state
preparation of two entangled photons and feedback control of quantum
interference. These results point the way to a single platform that will enable
the integration of nonlinear single photon sources and fast reconfigurable
circuits for future photonic quantum information science and technology.Comment: 6 page
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
Qubit entanglement between ring-resonator photon-pair sources on a silicon chip
Entanglement—one of the most delicate phenomena in nature—is an essential resource for quantum information applications. Scalable photonic quantum devices must generate and control qubit entanglement on-chip, where quantum information is naturally encoded in photon path. Here we report a silicon photonic chip that uses resonant-enhanced photon-pair sources, spectral demultiplexers and reconfigurable optics to generate a path-entangled two-qubit state and analyse its entanglement. We show that ring-resonator-based spontaneous four-wave mixing photon-pair sources can be made highly indistinguishable and that their spectral correlations are small. We use on-chip frequency demultiplexers and reconfigurable optics to perform both quantum state tomography and the strict Bell-CHSH test, both of which confirm a high level of on-chip entanglement. This work demonstrates the integration of high-performance components that will be essential for building quantum devices and systems to harness photonic entanglement on the large scale
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