Speaker
Mr.
Ivan Supic
(ICFO - Institut de Ciencies Fotoniques)
Description
A very timely enterprise nowadays is to understand which states can be self-tested and how. This question has been answered recently in the bipartite case, while it is largely unexplored in the multipartite case, with only a few scattered results, using a variety of different methods: maximal violation of a corresponding Bell inequality, numerical SWAP method, stabilizer self-testing etc. This also explains why it is not clear which states can be self-tested. In our work, we propose a unifying approach: combining projections to two-qubit spaces (projecting parties or degrees of freedom) and then using the maximal violation of tilted CHSH inequalities. In the qubit case, using this simple but general approach, we show that almost all multipartite qubit states can be self-tested (albeit with many measurements), namely all the ones that can be written with all real coefficients in some basis. In particular, this result is enough to characterize the tripartite case completely. Moreover, for special classes of multipartite states, like symmetric Dicke states and graph states, our approach yields a self-test with few measurements. Finally, for the qudit case, we show that all multipartite states which admit a Schmidt decomposition can be self-tested with few measurements
Primary author
Mr.
Ivan Supic
(ICFO - Institut de Ciencies Fotoniques)
Co-authors
Mr.
Andrea Coladangelo
(California Institute of Technology)
Mr.
Antonio Acin
(ICFO)
Mr.
Remigiusz Augusiak
(Polish Academy of Sciences)