Indefinite causal structures for continuous-variable systems
- Author(s)
- Flaminia Giacomini, Esteban Castro-Ruiz, Caslav Brukner
- Abstract
In all our well-established theories, it is assumed that events are embedded in a global causal structure such that, for every pair of events, the causal order between them is always fixed. However, the possible interplay between quantum mechanics and general relativity may require a revision of this paradigm. The process matrix framework keeps the validity of quantum physics locally but does not assume the existence of a global causal order. It allows to describe causal structures corresponding to a quantum superposition of 'A is before B' and 'B is before A'. So far, the framework has been developed only for finite-dimensional systems, and a straightforward generalization to infinite dimensions leads to singularities. Such generalization is necessary for continuous-variable systems and is a prerequisite for quantum fields on indefinite causal structures. Here we develop the process-matrix framework for continuous-variable systems. We encounter and solve the problems of singularities. Moreover, we study an example of a process in infinite dimensions, and we derive correlations exhibiting intereference due to processes in which A is before B and B is before A.
- Organisation(s)
- Quantum Optics, Quantum Nanophysics and Quantum Information
- External organisation(s)
- Österreichische Akademie der Wissenschaften (ÖAW)
- Journal
- New Journal of Physics
- Volume
- 18
- No. of pages
- 8
- ISSN
- 1367-2630
- DOI
- https://doi.org/10.1088/1367-2630/18/11/113026
- Publication date
- 11-2016
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103024 Quantum field theory, 103025 Quantum mechanics
- Keywords
- ASJC Scopus subject areas
- General Physics and Astronomy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/1f824b48-8b3e-4083-a34f-9a5286597579