  Formal similarity between Minkowski tetrads and Bell bases allows to think of
metric tensors in terms of quantum teleportation protocols. The role of null
tetrads for quantum information processing is different. They define qubits
resistant to a special kind of noise that occurs if coding and decoding of
quantum information is performed in different reference frames. These examples
show that mutual links between quantum information and the 2-spinor calculus
may be nontrivial and worthy of further studies.
