On Measures and Measurements: a Fibre Bundle approach to Contextuality

Contextuality is the failure of "local" probabilistic models to become global ones. In this paper we introduce the notions of \emph{measurable fibre bundles}, \emph{probability fibre bundles}, and \emph{sample fibre bundle} which capture and make precise the former statement. The central notions of contextuality are discussed under this formalism, examples worked out, and some new aspects pointed out.Comment: 14 pages; no figures; Purdue-Winer Memorial Lectures 2018; submitted to Phil. Trans. Roy. Soc. A. Comments are very welcom

How to Extract Entanglement from a Piece of Solid or a Bunch of Neutrons

We review how to obtain spin entangled pairs of fermions from a Fermi gas. An experiment with neutrons is proposed in order to get such pairs.Comment: Prepared for the Proceedings of Central European Workshop on Quantum Optics, Vienna - 200

Continuous Quantum Error Correction Through Local Operations

We propose local strategies to protect global quantum information. The protocols, which are quantum error correcting codes for dissipative systems, are based on environment measurements, direct feedback control and simple encoding of the logical qubits into physical qutrits whose decaying transitions are indistinguishable and equally probable. The simple addition of one extra level in the description of the subsystems allows for local actions to fully and deterministically protect global resources, such as entanglement. We present codes for both quantum jump and quantum state diffusion measurement strategies and test them against several sources of inefficiency. The use of qutrits in information protocols suggests further characterization of qutrit-qutrit disentanglement dynamics, which we also give together with simple local environment measurement schemes able to prevent distillability sudden death and even enhance entanglement in situations in which our feedback error correction is not possible.Comment: Accepted for publication in Phys. Rev.