Morphophoric POVMs, generalised qplexes, and 2-designs

Wojciech Słomczyński, Anna Szymusiak
<span title="2020-09-30">2020</span> <i title="Verein zur Forderung des Open Access Publizierens in den Quantenwissenschaften"> <a target="_blank" rel="noopener" href="" style="color: black;">Quantum</a> </i> &nbsp;
We study the class of quantum measurements with the property that the image of the set of quantum states under the measurement map transforming states into probability distributions is similar to this set and call such measurements morphophoric. This leads to the generalisation of the notion of a qplex, where SIC-POVMs are replaced by the elements of the much larger class of morphophoric POVMs, containing in particular 2-design (rank-1 and equal-trace) POVMs. The intrinsic geometry of a
more &raquo; ... sed qplex is the same as that of the set of quantum states, so we explore its external geometry, investigating, inter alia, the algebraic and geometric form of the inner (basis) and the outer (primal) polytopes between which the generalised qplex is sandwiched. In particular, we examine generalised qplexes generated by MUB-like 2-design POVMs utilising their graph-theoretical properties. Moreover, we show how to extend the primal equation of QBism designed for SIC-POVMs to the morphophoric case.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="">doi:10.22331/q-2020-09-30-338</a> <a target="_blank" rel="external noopener" href="">fatcat:por5m76xmbat3iaay6tavgfqpi</a> </span>
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