21,459 research outputs found
Integrated quantum optical networks based on quantum dots and photonic crystals
Single solid-state optical emitters have quantum mechanical properties that make them suitable for applications in information processing and sensing. Most of these quantum technologies rely on the capability to integrate the emitters in reliable solid-state optical networks. In this paper, we present integrated devices based on GaAs photonic crystals and InAs self-assembled quantum dots. These quantum networks are well suited to future optoelectronic devices operating at ultralow power levels, single-photon logic devices and quantum information processing
Continuous variable entanglement on a chip
Encoding quantum information in continuous variables (CV)---as the quadrature
of electromagnetic fields---is a powerful approach to quantum information
science and technology. CV entanglement---light beams in
Einstein-Podolsky-Rosen (EPR) states---is a key resource for quantum
information protocols; and enables hybridisation between CV and single photon
discrete variable (DV) qubit systems. However, CV systems are currently limited
by their implementation in free-space optical networks: increased complexity,
low loss, high-precision alignment and stability, as well as hybridisation,
demand an alternative approach. Here we show an integrated photonic
implementation of the key capabilities for CV quantum technologies---generation
and characterisation of EPR beams in a photonic chip. Combined with integrated
squeezing and non-Gaussian operation, these results open the way to universal
quantum information processing with light
A proposal for the implementation of quantum gates with photonic-crystal coupled cavity waveguides
Quantum computers require technologies that offer both sufficient control
over coherent quantum phenomena and minimal spurious interactions with the
environment. We show, that photons confined to photonic crystals, and in
particular to highly efficient waveguides formed from linear chains of defects
doped with atoms can generate strong non-linear interactions which allow to
implement both single and two qubit quantum gates. The simplicity of the gate
switching mechanism, the experimental feasibility of fabricating two
dimensional photonic crystal structures and integrability of this device with
optoelectronics offers new interesting possibilities for optical quantum
information processing networks.Comment: 4 pages, 3 figure
Generation of Complex Quantum States Via Integrated Frequency Combs
The generation of optical quantum states on an integrated platform will enable low cost and accessible advances for quantum technologies such as secure communications and quantum computation. We demonstrate that integrated quantum frequency combs (based on high-Q microring resonators made from a CMOS-compatible, high refractive-index glass platform) can enable, among others, the generation of heralded single photons, cross-polarized photon pairs, as well as bi- and multi-photon entangled qubit states over a broad frequency comb covering the S, C, L telecommunications band, constituting an important cornerstone for future practical implementations of photonic quantum information processing
Interfacing GHz-bandwidth heralded single photons with a room-temperature Raman quantum memory
Photonics is a promising platform for quantum technologies. However, photon
sources and two-photon gates currently only operate probabilistically.
Large-scale photonic processing will therefore be impossible without a
multiplexing strategy to actively select successful events. High
time-bandwidth-product quantum memories - devices that store and retrieve
single photons on-demand - provide an efficient remedy via active
synchronisation. Here we interface a GHz-bandwidth heralded single-photon
source and a room-temperature Raman memory with a time-bandwidth product
exceeding 1000. We store heralded single photons and observe a clear influence
of the input photon statistics on the retrieved light, which agrees with our
theoretical model. The preservation of the stored field's statistics is limited
by four-wave-mixing noise, which we identify as the key remaining challenge in
the development of practical memories for scalable photonic information
processing
One- and two-dimensional photonic crystal micro-cavities in single crystal diamond
The development of solid-state photonic quantum technologies is of great
interest for fundamental studies of light-matter interactions and quantum
information science. Diamond has turned out to be an attractive material for
integrated quantum information processing due to the extraordinary properties
of its colour centres enabling e.g. bright single photon emission and spin
quantum bits. To control emitted photons and to interconnect distant quantum
bits, micro-cavities directly fabricated in the diamond material are desired.
However, the production of photonic devices in high-quality diamond has been a
challenge so far. Here we present a method to fabricate one- and
two-dimensional photonic crystal micro-cavities in single-crystal diamond,
yielding quality factors up to 700. Using a post-processing etching technique,
we tune the cavity modes into resonance with the zero phonon line of an
ensemble of silicon-vacancy centres and measure an intensity enhancement by a
factor of 2.8. The controlled coupling to small mode volume photonic crystal
cavities paves the way to larger scale photonic quantum devices based on
single-crystal diamond
How far can one send a photon?
The answer to the question {\it How far can one send a photon?} depends
heavily on what one means by {\it a photon} and on what one intends to do with
that photon. For direct quantum communication the limit is of about 500 km. For
terrestrial quantum communication, near future technologies based on quantum
teleportation and quantum memories will soon enable quantum repeaters that will
turn the development of a world-wide-quantum-web (WWQW) into a (highly
non-trivial) engineering problem. For Device Independent Quantum Information
Processing, near future qubit amplifiers (i.e. probabilistic heralded
amplification of the probability amplitude of presence of photonic qubits) will
soon allow demonstrations over a few tens of km.Comment: Proceedings of QCMC 2014, Hefei. 6 pages Correction of an annoying
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