Noise-powered entanglement detection

Entangled particles exhibit quantum correlations over arbitrary long distances in time and space which cannot be mimicked by local realistic models. In order to detect and utilize these correlations for quantum information tasks, measurements in different bases are necessary. A variety of schemes for experimentally characterizing quantum states have been devised. However, these are often experimentally demanding in terms of stability and insensitivity against noise. Standard methods such as state tomography and Bell tests [1, 2] will fail to reliably detect quantum correlations in the presence of unknown local perturbations to the measuring apparatus, as consecutive measurements must be co-ordinated via a shared choice of measurement basis (a shared reference frame). So called reference frame independent schemes overcome this difficulty [3, 4], however, even these schemes fail when the choice of local measurement setting is not repeatable, i.e. when there is drift.