We show -- both theoretically and experimentally -- that Einstein-Podolsky-Rosen steering can be distilled. We present a distillation protocol that outputs a perfectly correlated system -- the singlet assemblage -- in the asymptotic infinite-copy limit, even for inputs that are arbitrarily close to being unsteerable. As figures of merit for the protocol's performance, we introduce the assemblage fidelity and the singlet-assemblage fraction. These are potentially interesting quantities on their own beyond the current scope. Remarkably, the protocol works well also in the non-asymptotic regime of few copies, in the sense of increasing the singlet-assemblage fraction. We demonstrate the efficacy of the protocol using a hyperentangled photon pair encoding two copies of a two-qubit state. This represents to our knowledge the first observation of deterministic steering concentration. Our findings are not only fundamentally important but may also be useful for semi device-independent protocols in noisy quantum networks.
@article{arxiv.1906.00991,
title = {Distillation of quantum steering},
author = {R. V. Nery and M. M. Taddei and P. Sahium and S. P. Walborn and L. Aolita and G. H. Aguilar},
journal= {arXiv preprint arXiv:1906.00991},
year = {2020}
}
Comments
6+4 pages, 3 figures. Accepted for publication in Physical Review Letters