13,201 research outputs found
Experimental quantum key distribution with simulated ground-to-satellite photon losses and processing limitations
Quantum key distribution (QKD) has the potential to improve communications
security by offering cryptographic keys whose security relies on the
fundamental properties of quantum physics. The use of a trusted quantum
receiver on an orbiting satellite is the most practical near-term solution to
the challenge of achieving long-distance (global-scale) QKD, currently limited
to a few hundred kilometers on the ground. This scenario presents unique
challenges, such as high photon losses and restricted classical data
transmission and processing power due to the limitations of a typical satellite
platform. Here we demonstrate the feasibility of such a system by implementing
a QKD protocol, with optical transmission and full post-processing, in the
high-loss regime using minimized computing hardware at the receiver. Employing
weak coherent pulses with decoy states, we demonstrate the production of secure
key bits at up to 56.5 dB of photon loss. We further illustrate the feasibility
of a satellite uplink by generating secure key while experimentally emulating
the varying channel losses predicted for realistic low-Earth-orbit satellite
passes at 600 km altitude. With a 76 MHz source and including finite-size
analysis, we extract 3374 bits of secure key from the best pass. We also
illustrate the potential benefit of combining multiple passes together: while
one suboptimal "upper-quartile" pass produces no finite-sized key with our
source, the combination of three such passes allows us to extract 165 bits of
secure key. Alternatively, we find that by increasing the signal rate to 300
MHz it would be possible to extract 21570 bits of secure finite-sized key in
just a single upper-quartile pass.Comment: 12 pages, 7 figures, 2 table
Proof-of-Concept Experiments for Quantum Physics in Space
Quantum physics experiments in space using entangled photons and satellites
are within reach of current technology. We propose a series of fundamental
quantum physics experiments that make advantageous use of the space
infrastructure with specific emphasis on the satellite-based distribution of
entangled photon pairs. The experiments are feasible already today and will
eventually lead to a Bell-experiment over thousands of kilometers, thus
demonstrating quantum correlations over distances which cannot be achieved by
purely earth-bound experiments.Comment: 15 pages, 10 figures, to appear in: SPIE Proceedings on Quantum
Communications and Quantum Imaging (2003
Quantum Communication Uplink to a 3U CubeSat: Feasibility & Design
Satellites are the efficient way to achieve global scale quantum
communication (Q.Com) because unavoidable losses restrict fiber based Q.Com to
a few hundred kilometers. We demonstrate the feasibility of establishing a
Q.Com uplink with a tiny 3U CubeSat (measuring just 10X10X32 cm^3 ) using
commercial off-the-shelf components, the majority of which have space heritage.
We demonstrate how to leverage the latest advancements in nano-satellite
body-pointing to show that our 4kg CubeSat can provide performance comparable
to much larger 600kg satellite missions. A comprehensive link budget and
simulation was performed to calculate the secure key rates. We discuss design
choices and trade-offs to maximize the key rate while minimizing the cost and
development needed. Our detailed design and feasibility study can be readily
used as a template for global scale Q.Com.Comment: 24 pages, 9 figures, 2 tables. Fixed tables and figure
Towards a Distributed Quantum Computing Ecosystem
The Quantum Internet, by enabling quantum communications among remote quantum
nodes, is a network capable of supporting functionalities with no direct
counterpart in the classical world. Indeed, with the network and communications
functionalities provided by the Quantum Internet, remote quantum devices can
communicate and cooperate for solving challenging computational tasks by
adopting a distributed computing approach. The aim of this paper is to provide
the reader with an overview about the main challenges and open problems arising
with the design of a Distributed Quantum Computing ecosystem. For this, we
provide a survey, following a bottom-up approach, from a communications
engineering perspective. We start by introducing the Quantum Internet as the
fundamental underlying infrastructure of the Distributed Quantum Computing
ecosystem. Then we go further, by elaborating on a high-level system
abstraction of the Distributed Quantum Computing ecosystem. Such an abstraction
is described through a set of logical layers. Thereby, we clarify dependencies
among the aforementioned layers and, at the same time, a road-map emerges
- …