Causality in higher-order quantum theory
Quantum channels, superchannels, and indefinite causal order
Presented as a tutorial at QPL 2026 — 23rd International Conference on Quantum Physics and Logic (Amsterdam, the Netherlands, 2026).
Tutorial date: 16 August 2026.
This tutorial will provide an overview of indefinite causal order in quantum information theory, from the perspective of higher-order quantum operations. We examine the structural aspects of the framework, showing how transformations of quantum channels can go beyond the quantum circuit model by describing computations without a fixed causal order. We discuss which computational tasks can benefit from this feature, as well as the resources required to simulate such advantages within standard quantum circuits. Finally, we turn to a more operational perspective, outlining how these transformations can generate correlations that violate causal inequalities.
Course materials
View or download the slides (PDF)
