The Cost of Quantum Locality*

It has been more than 20 years since Deutsch and Hayden^[1] demonstrated that quantum systems can be completely described locally — notwithstanding Bell's theorem. More recently, Raymond-Robichaud^[2] proposed another approach to the same conclusion. The cost of such local descriptions is quantified by the dimensionality of their space. The central result is that the dimension of a single qubit's description grows exponentially with the size of the total system considered, in sharp contrast with the mere three dimensionality of the reduced density matrix. However, the apparently unreasonable cost is shown to be expected of any local and complete description of quantum systems.
The talk is based on arXiv:2001.09646.

1. Deutsch, D. & Hayden, P. 2000 Proc. R. Soc. Lond. Series A 456, 1759-1774.
2. Raymond-Robichaud, P. 2020 Preprint arXiv:2010.14303.