# Quantum speedup in testing causal hypotheses

### APA

Chiribella, G. (2018). Quantum speedup in testing causal hypotheses. Perimeter Institute. https://pirsa.org/18040122

### MLA

Chiribella, Giulio. Quantum speedup in testing causal hypotheses. Perimeter Institute, Apr. 09, 2018, https://pirsa.org/18040122

### BibTex

@misc{ pirsa_PIRSA:18040122, doi = {10.48660/18040122}, url = {https://pirsa.org/18040122}, author = {Chiribella, Giulio}, keywords = {Quantum Foundations}, language = {en}, title = {Quantum speedup in testing causal hypotheses}, publisher = {Perimeter Institute}, year = {2018}, month = {apr}, note = {PIRSA:18040122 see, \url{https://pirsa.org}} }

University of Hong Kong (HKU)

Talk Type

**Subject**

Abstract

An important ingredient of the scientific method is the ability to test alternative hypotheses on the causal relations relating a given set of variables. In the classical world, this task can be achieved with a variety of statistical, information-theoretic, and computational techniques. In this talk I will address the extension from the classical scenario to the quantum scenario, and, more generally, to general probabilistic theories. After introducing the basic hypothesis testing framework, I will focus on a concrete example, where the task is to identify the causal intermediary of a given variable, under the promise that the causal intermediary belongs to a given set of candidate variables. In this problem, I will show that quantum physics offers an exponential advantage over the best classical strategies, with a doubling of the exponential decay of the error probability. The source of the advantage can be found in the combination of two quantum features: the complementarity between the information on the causal structure and other properties of the cause effect relation, and the ability to perform multiple tests in a quantum superposition. An interesting possibility is that one of the "hidden principles" of quantum theory could be on our ability to test alternative causal hypotheses.