Testing Quantum Randomness in Single-Photon Polarization Measurements

David A. Branning, Matthew Bermudez

A binary sequence was constructed from 1.7×107 polarization measurements of single photons from a spontaneous parametric downconversion source, under pumping conditions similar to those used in optical quantum cryptography. To search for correlations in the polarization measurement outcomes, we subjected the sequence to a suite of tests developed at the National Institute of Standards and Technology (NIST) for the assessment of algorithmic random-number generators. The bias of the sequence was low enough to allow all fifteen tests to be applied directly to the polarization outcomes without using any numerical unbiasing procedures. No statistically significant deviations from randomness were observed, other than those related to this small uncorrected bias.

Jeremy L. O’Brien, Geoff J. Pryde, AG White +2 more

M. Iinuma

David A. Branning, Adam Katcher, Wayne Strange +1 more

Sequences of random binary numbers created from polarization measurements of single photons were subjected to a comprehensive runs analysis. Photon pairs from a spontaneous parametric downconversion source were detected in coincidence, with one photon acting as a trigger while the other was analyzed for horizontal or vertical polarization. The resulting sequences of polarization measurements were tested for runs of consecutive vertical or horizontal outcomes against a theory of nonoverlapping runs, without numerical unbiasing. The sequences produced no statistically significant discrepancies with the predicted numbers of runs, even with multiphoton events retained.

Sofia Fahlvik Svensson, Mohamed Bourennane

Naofumi Abe, Yasuyoshi Mitsumori, Mark Sadgrove +1 more

Single-photon sources are essential tools for quantum information technology and testing the foundations of quantum theory. To date, single-photon sources which emit purely polarized single photons (e.g. horizontal polarization and vertical polarization) have been realized in various ways. On the other hand, single-photon sources which emit completely unpolarized single photons are also important for applications such as realizing hardware random number generators and testing the foundations of quantum theory such as the error-disturbance relation for mixed states [1, 2] which are quantum states of unpolarized polarization states. Here, we present a dynamically and statically unpolarized single-photon source using a single nitrogen-vacancy (NV) center in diamond. In particular, we demonstrate a new method for evaluation of dynamical unpolarization using the second order correlation function [3].