32 research outputs found
Von Neumann Normalisation of a Quantum Random Number Generator
In this paper we study von Neumann un-biasing normalisation for ideal and
real quantum random number generators, operating on finite strings or infinite
bit sequences. In the ideal cases one can obtain the desired un-biasing. This
relies critically on the independence of the source, a notion we rigorously
define for our model. In real cases, affected by imperfections in measurement
and hardware, one cannot achieve a true un-biasing, but, if the bias "drifts
sufficiently slowly", the result can be arbitrarily close to un-biasing. For
infinite sequences, normalisation can both increase or decrease the
(algorithmic) randomness of the generated sequences. A successful application
of von Neumann normalisation---in fact, any un-biasing transformation---does
exactly what it promises, un-biasing, one (among infinitely many) symptoms of
randomness; it will not produce "true" randomness.Comment: 27 pages, 2 figures. Updated to published versio
Multiplexed Quantum Random Number Generation
Fast secure random number generation is essential for high-speed encrypted
communication, and is the backbone of information security. Generation of truly
random numbers depends on the intrinsic randomness of the process used and is
usually limited by electronic bandwidth and signal processing data rates. Here
we use a multiplexing scheme to create a fast quantum random number generator
structurally tailored to encryption for distributed computing, and high
bit-rate data transfer. We use vacuum fluctuations measured by seven homodyne
detectors as quantum randomness sources, multiplexed using a single integrated
optical device. We obtain a random number generation rate of 3.08 Gbit/s, from
only 27.5 MHz of sampled detector bandwidth. Furthermore, we take advantage of
the multiplexed nature of our system to demonstrate an unseeded strong
extractor with a generation rate of 26 Mbit/s.Comment: 10 pages, 3 figures and 1 tabl
Classical, quantum and biological randomness as relative unpredictability
International audienceWe propose the thesis that randomness is unpredictability with respect to an intended theory and measurement. From this point view we briefly discuss various forms of randomness that physics, mathematics and computing science have proposed. Computing science allows to discuss unpredictability in an abstract, yet very expressive way, which yields useful hierarchies of randomness and may help to relate its various forms in natural sciences. Finally we discuss biological randomness — its peculiar nature and role in ontogenesis and in evolutionary dynamics (phylogenesis). Randomness in biology has a positive character as it contributes to the organisms' and populations' structural stability by adaptation and diversity. Abstract We propose the thesis that randomness is unpredictability with respect to an intended theory and measurement. From this point view we briefly discuss various forms of randomness that physics, mathematics and computing science have proposed. Computing science allows to discuss unpredictability in an abstract, yet very expressive way, which yields useful hierarchies of randomness and may help to relate its various forms in natural sciences. Finally we discuss biological randomness—its peculiar nature and role in ontogenesis and in evolutionary dynamics (phylogenesis). Randomness in biology has a positive character as it contributes to the organisms' and populations' structural stability by adaptation and diversity