1,598 research outputs found
Complete elimination of information leakage in continuous-variable quantum communication channels
In all lossy communication channels realized to date, information is
inevitably leaked to a potential eavesdropper. Here we present a communication
protocol that does not allow for any information leakage to a potential
eavesdropper in a purely lossy channel. By encoding information into a
restricted Gaussian alphabet of squeezed states we show, both theoretically and
experimentally, that the Holevo information between the eavesdropper and the
intended recipient can be exactly zero in a purely lossy channel while
minimized in a noisy channel. This result is of fundamental interest, but might
also have practical implications in extending the distance of secure quantum
key distribution.Comment: 9 pages, 5 figure
Experimental Investigation of the Evolution of Gaussian Quantum Discord in an Open System
Gaussian quantum discord is a measure of quantum correlations in Gaussian
systems. Using Gaussian discord we quantify the quantum correlations of a
bipartite entangled state and a separable two-mode mixture of coherent states.
We experimentally analyze the effect of noise addition and dissipation on
Gaussian discord and show that the former noise degrades the discord while the
latter noise for some states leads to an increase of the discord. In
particular, we experimentally demonstrate the near-death of discord by noisy
evolution and its revival through dissipation.Comment: 5 pages, 5 figure
Probabilistic Cloning of Coherent States without a Phase Reference
We present a probabilistic cloning scheme operating independently of any
phase reference. The scheme is based solely on a phase-randomized displacement
and photon counting, omitting the need for non-classical resources and
non-linear materials. In an experimental implementation, we employ the scheme
to clone coherent states from a phase covariant alphabet and demonstrate that
the cloner is capable of outperforming the hitherto best-performing
deterministic scheme. An analysis of the covariances between the output states
shows that uncorrelated clones can be approached asymptotically. An intriguing
feature is that the trade-off between success rate and achieved fidelity can be
optimized even after the cloning procedure
Deterministic teleportation using single-photon entanglement as a resource
We outline a proof that teleportation with a single particle is in principle
just as reliable as with two particles. We thereby hope to dispel the
skepticism surrounding single-photon entanglement as a valid resource in
quantum information. A deterministic Bell state analyzer is proposed which uses
only classical resources, namely coherent states, a Kerr non-linearity, and a
two-level atom.Comment: 6 pages, 4 figure
Towards Error Handling in a DSL for Robot Assembly Tasks
This work-in-progress paper presents our work with a domain specific language
(DSL) for tackling the issue of programming robots for small-sized batch
production. We observe that as the complexity of assembly increases so does the
likelihood of errors, and these errors need to be addressed. Nevertheless, it
is essential that programming and setting up the assembly remains fast, allows
quick changeovers, easy adjustments and reconfigurations. In this paper we
present an initial design and implementation of extending an existing DSL for
assembly operations with error specification, error handling and advanced move
commands incorporating error tolerance. The DSL is used as part of a framework
that aims at tackling uncertainties through a probabilistic approach.Comment: Presented at DSLRob 2014 (arXiv:cs/1411.7148
Convolutive Blind Source Separation Methods
In this chapter, we provide an overview of existing algorithms for blind source separation of convolutive audio mixtures. We provide a taxonomy, wherein many of the existing algorithms can be organized, and we present published results from those algorithms that have been applied to real-world audio separation tasks
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