93,098 research outputs found
Towards Large-Scale Quantum Networks
The vision of a quantum internet is to fundamentally enhance Internet
technology by enabling quantum communication between any two points on Earth.
While the first realisations of small scale quantum networks are expected in
the near future, scaling such networks presents immense challenges to physics,
computer science and engineering. Here, we provide a gentle introduction to
quantum networking targeted at computer scientists, and survey the state of the
art. We proceed to discuss key challenges for computer science in order to make
such networks a reality.Comment: To be presented at the Sixth Annual ACM International Conference on
Nanoscale Computing and Communication, Dublin, Irelan
An Elementary Quantum Network of Single Atoms in Optical Cavities
Quantum networks are distributed quantum many-body systems with tailored
topology and controlled information exchange. They are the backbone of
distributed quantum computing architectures and quantum communication. Here we
present a prototype of such a quantum network based on single atoms embedded in
optical cavities. We show that atom-cavity systems form universal nodes capable
of sending, receiving, storing and releasing photonic quantum information.
Quantum connectivity between nodes is achieved in the conceptually most
fundamental way: by the coherent exchange of a single photon. We demonstrate
the faithful transfer of an atomic quantum state and the creation of
entanglement between two identical nodes in independent laboratories. The
created nonlocal state is manipulated by local qubit rotation. This efficient
cavity-based approach to quantum networking is particularly promising as it
offers a clear perspective for scalability, thus paving the way towards
large-scale quantum networks and their applications.Comment: 8 pages, 5 figure
Dynamic acousto-mechanical control of a strongly coupled photonic molecule
Two-dimensional photonic crystal membranes provide a versatile planar
architecture for integrated photonics to control the propagation of light on a
chip employing high quality optical cavities, waveguides, beamsplitters or
dispersive elements. When combined with highly non-linear quantum emitters,
quantum photonic networks operating at the single photon level come within
reach. Towards large-scale quantum photonic networks, selective dynamic control
of individual components and deterministic interactions between different
constituents are of paramount importance. This indeed calls for switching
speeds ultimately on the system's native timescales. For example, manipulation
via electric fields or all-optical means have been employed for switching in
nanophotonic circuits and cavity quantum electrodynamics studies. Here, we
demonstrate dynamic control of the coherent interaction between two coupled
photonic crystal nanocavities forming a photonic molecule. By using an
electrically generated radio frequency surface acoustic wave we achieve
optomechanical tuning, demonstrate operating speeds more than three orders of
magnitude faster than resonant mechanical approaches. Moreover, the tuning
range is large enough to compensate for the inherent fabrication-related cavity
mode detuning. Our findings open a route towards nanomechanically gated
protocols, which hitherto have inhibited the realization in all-optical
schemes.Comment: submitted manuscrip
Optical interface created by laser-cooled atoms trapped in the evanescent field surrounding an optical nanofiber
Trapping and optically interfacing laser-cooled neutral atoms is an essential
requirement for their use in advanced quantum technologies. Here we
simultaneously realize both of these tasks with cesium atoms interacting with a
multi-color evanescent field surrounding an optical nanofiber. The atoms are
localized in a one-dimensional optical lattice about 200 nm above the nanofiber
surface and can be efficiently interrogated with a resonant light field sent
through the nanofiber. Our technique opens the route towards the direct
integration of laser-cooled atomic ensembles within fiber networks, an
important prerequisite for large scale quantum communication schemes. Moreover,
it is ideally suited to the realization of hybrid quantum systems that combine
atoms with, e.g., solid state quantum devices
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