Q27 — How accurately can physical devices implement singlet–triplet projection?

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Discussion of Q27: How accurately can physical devices implement singlet–triplet projection?.

Compare physical singlet/triplet measurements with the ideal projection, including coherence within each sector, leakage, loss, and repeatability.

Possible reductions, counterexamples, special cases, and related results are welcome. Please state the assumptions and link to relevant work.

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