3,393 research outputs found
Quantum information processing with space-division multiplexing optical fibres
The optical fibre is an essential tool for our communication infrastructure
since it is the main transmission channel for optical communications. The
latest major advance in optical fibre technology is spatial division
multiplexing (SDM), where new fibre designs and components establish multiple
co-existing data channels based on light propagation over distinct transverse
optical modes. Simultaneously, there have been many recent developments in the
field of quantum information processing (QIP), with novel protocols and devices
in areas such as computing, communication and metrology. Here, we review recent
works implementing QIP protocols with SDM optical fibres, and discuss new
possibilities for manipulating quantum systems based on this technology.Comment: Originally submitted version. Please see published version for
improved layout, new tables and updated references following review proces
Twisted Photons: New Quantum Perspectives in High Dimensions
Quantum information science and quantum information technology have seen a
virtual explosion world-wide. It is all based on the observation that
fundamental quantum phenomena on the individual particle or system-level lead
to completely novel ways of encoding, processing and transmitting information.
Quantum mechanics, a child of the first third of the 20th century, has found
numerous realizations and technical applications, much more than was thought at
the beginning. Decades later, it became possible to do experiments with
individual quantum particles and quantum systems. This was due to technological
progress, and for light in particular, the development of the laser. Hitherto,
nearly all experiments and also nearly all realizations in the fields have been
performed with qubits, which are two-level quantum systems. We suggest that
this limitation is again mainly a technological one, because it is very
difficult to create, manipulate and measure more complex quantum systems. Here,
we provide a specific overview of some recent developments with
higher-dimensional quantum systems. We mainly focus on Orbital Angular Momentum
(OAM) states of photons and possible applications in quantum information
protocols. Such states form discrete higher-dimensional quantum systems, also
called qudits. Specifically, we will first address the question what kind of
new fundamental properties exist and the quantum information applications which
are opened up by such novel systems. Then we give an overview of recent
developments in the field by discussing several notable experiments over the
past 2-3 years. Finally, we conclude with several important open questions
which will be interesting for investigations in the future.Comment: 15 pages, 7 figure
Simultaneous entanglement swapping of multiple orbital angular momentum states of light
Entanglement swapping generates remote quantum correlations between particles
that have not interacted and is the cornerstone of long-distance quantum
communication, quantum networks, and fundamental tests of quantum science. In
the context of spatial modes of light, high-dimensional entanglement provides
an avenue to increase the bandwidth of quantum communications and provides more
stringent limits for tests of quantum foundations. Here we simultaneously swap
the entanglement of multiple orbital angular momentum states of light. The
system is based on a degenerate filter that cannot distinguish between
different anti-symmetric states, and thus entanglement swapping occurs for
several thousand pairs of spatial light modes simultaneously
Quantum Sensors: Improved Optical Measurement via Specialized Quantum States
Classical measurement strategies in many areas are approaching their maximum
resolution and sensitivity levels, but these levels often still fall far short
of the ultimate limits allowed by the laws of physics. To go further,
strategies must be adopted that take into account the quantum nature of the
probe particles and that optimize their quantum states for the desired
application. Here, we review some of these approaches, in which quantum
entanglement, the orbital angular momentum of single photons, and quantum
interferometry are used to produce optical measurements beyond the classical
limit
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