2017/11/11 by Simon Milz, Felix A. Pollock, Thao P. Le +2
Computer Science · Mathematics · Physics and Astronomy · #Causal structure #Causality (physics) #Classical mechanics #Computer science #Connection (principal bundle) #Degrees of freedom (physics and chemistry) #Markov process #Mathematics #Physics #Process (computing) #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum entanglement #Quantum mechanics #Statistical physics #Theoretical physics #Unitary state #quant-ph
paper · pdf · doi:10.1088/1367-2630/aaafee
published as New J. Phys. 20, 033033 (2018) · 14 pages, 8 figures
arxiv created 2017/11/11 · openalex publication_date 2018/02/16 · arxiv updated 2018/04/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Quantum mechanics, in principle, allows for processes with indefinite causal order. However, most of these causal anomalies have not yet been detected experimentally. We show that every such process can be simulated experimentally by means of non-Markovian dynamics with a measurement on additional degrees of freedom. In detail, we provide an explicit construction to implement arbitrary a causal processes. Furthermore, we give necessary and sufficient conditions for open system dynamics with measurement to yield processes that respect causality locally, and find that tripartite entanglement and nonlocal unitary transformations are crucial requirements for the simulation of causally indefinite processes. These results show a direct connection between three counter-intuitive concepts: entanglement, non-Markovianity, and causal non-separability.