



01481nas a2200157   4500008004100000245006800041210006700109260001500176300001000191490000800201520102300209100002101232700001601253700001701269856003701286       2019                        eng d00aParallel Self-Testing of the GHZ State with a Proof by Diagrams0 aParallel SelfTesting of the GHZ State with a Proof by Diagrams  c01/29/2019  a43-660 v2873 a<p>Quantum self-testing addresses the following question: is it possible to verify the existence of a multipartite state even when one&#39;s measurement devices are completely untrusted? This problem has seen abundant activity in the last few years, particularly with the advent of parallel self-testing (i.e., testing several copies of a state at once), which has applications not only to quantum cryptography but also quantum computing. In this work we give the first error-tolerant parallel self-test in a three-party (rather than two-party) scenario, by showing that an arbitrary number of copies of the GHZ state can be self-tested. In order to handle the additional complexity of a three-party setting, we use a diagrammatic proof based on categorical quantum mechanics, rather than a typical symbolic proof. The diagrammatic approach allows for manipulations of the complicated tensor networks that arise in the proof, and gives a demonstration of the importance of picture-languages in quantum information.</p>1 aBreiner, Spencer1 aKalev, Amir1 aMiller, Carl  uhttps://arxiv.org/abs/1806.04744