A purification postulate for quantum mechanics with indefinite causal order
Year: 2017
Type: article
Abstract: To study which are the most general causal structures which are compatible with local quantum mechanics, Oreshkov e t a l . \cite{oreshkov12} introduced the notion of a process: a resource shared between some parties that allows for quantum communication between them without a predetermined causal order. These processes can be used to perform several tasks that are impossible in standard quantum mechanics: they allow for the violation of causal inequalities, and provide an advantage for computational and communication complexity. Nonetheless, no process that can be used to violate a causal inequality is known to be physically implementable. There is therefore considerable interest in determining which processes are physical and which are just mathematical artefacts of the framework. Here we make key progress in this direction by proposing a purification postulate: processes are physical only if they are purifiable. We derive necessary conditions for a process to be purifiable, and show that several known processes do not satisfy them.
Source: Quantum
Authors: Mateus Araújo, Adrien Feix, Miguel Navascués, Časlav Brukner
Institutions: University of Vienna, University of Cologne
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $215
OpenAlex ID: W2559071265