← Open problems
MUB-10.11
What does it mean for a physical system if inequivalent complementary pairs of observables exist?
In plain terms
Interpretational. Inequivalent pairs exist already for two qubits, yet are not known to differ operationally.
Our position — ours alone, not the authors'
Not a computational question.
Source
Daniel McNulty, Stefan Weigert, Mutually Unbiased Bases in Composite Dimensions -- A Review
Quantum 10, 2051 (2026) · §10.3
https://doi.org/10.22331/q-2026-04-01-2051
Licence:
CC-BY-4.0
— the problem statement is quoted here under that
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