Research output: Contribution to journal › Article

**Free randomness can be amplified.** / Colbeck, Roger; Renner, Renato.

Research output: Contribution to journal › Article

Colbeck, R & Renner, R 2012, 'Free randomness can be amplified', *Nature Physics*, vol. 8, no. 6, pp. 449-452. https://doi.org/10.1038/NPHYS2300

Colbeck, R., & Renner, R. (2012). Free randomness can be amplified. *Nature Physics*, *8*(6), 449-452. https://doi.org/10.1038/NPHYS2300

Colbeck R, Renner R. Free randomness can be amplified. Nature Physics. 2012 Jun;8(6):449-452. https://doi.org/10.1038/NPHYS2300

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title = "Free randomness can be amplified",

abstract = "Are there fundamentally random processes in nature? Theoretical predictions, confirmed experimentally, such as the violation of Bell inequalities(1), point to an affirmative answer. However, these results are based on the assumption that measurement settings can be chosen freely at random(2), so assume the existence of perfectly free random processes from the outset. Here we consider a scenario in which this assumption is weakened and show that partially free random bits can be amplified to make arbitrarily free ones. More precisely, given a source of random bits whose correlation with other variables is below a certain threshold, we propose a procedure for generating fresh random bits that are virtually uncorrelated with all other variables. We also conjecture that such procedures exist for any non-trivial threshold. Our result is based solely on the no-signalling principle, which is necessary for the existence of free randomness.",

author = "Roger Colbeck and Renato Renner",

year = "2012",

month = "6",

doi = "10.1038/NPHYS2300",

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journal = "Nature Physics",

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AB - Are there fundamentally random processes in nature? Theoretical predictions, confirmed experimentally, such as the violation of Bell inequalities(1), point to an affirmative answer. However, these results are based on the assumption that measurement settings can be chosen freely at random(2), so assume the existence of perfectly free random processes from the outset. Here we consider a scenario in which this assumption is weakened and show that partially free random bits can be amplified to make arbitrarily free ones. More precisely, given a source of random bits whose correlation with other variables is below a certain threshold, we propose a procedure for generating fresh random bits that are virtually uncorrelated with all other variables. We also conjecture that such procedures exist for any non-trivial threshold. Our result is based solely on the no-signalling principle, which is necessary for the existence of free randomness.

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