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QI: Fachverband Quanteninformation

QI 29: Quantum Information: Concepts and Methods I

QI 29.5: Vortrag

Donnerstag, 13. März 2025, 12:15–12:30, HS IV

Information processing without directional reference — •Konrad Szymański¹ and Fynn Otto² — ¹Research Center for Quantum Information, Bratislava — ²Universität Siegen, Siegen

If a quantum operation commutes with a group of transformations, it is called group-covariant. In practical scenarios, the unknown group transformation may contribute to noise, represent a parameter to be estimated, or intentionally scramble information. In all these cases, there exist nontrivial operations which can be applied before or after the transformation with the same final result. Here, we present the recent observations related to SU(2) covariance. This group can be interpreted as physical spin rotations or passive 2-mode optical interferometry. We demonstrate how to characterize the states accessible with SU(2)-covariant operations, and discuss the applicability of this theory to quantum information processing tasks, including a variant of quantum key distribution performed without a shared reference frame, and probabilistic amplification of interferometer sensitivity.

Keywords: rotational symmetry; polynomial theory; interferometry; covariant channels; quantum key distribution