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Brown measure convergence under strong convergence (conjectural)

Prove that if a family of random matrices X^N strongly converges to a limiting family x in a C*-probability space, then for every noncommutative polynomial P the empirical distribution of the complex eigenvalues of P(X^N,(X^N)*) converges to the Brown measure of P(x,x*).

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Background

The Brown measure provides the natural notion of complex eigenvalue distribution in operator-algebraic settings. It is conjectured that strong convergence should force convergence of empirical complex spectra to Brown measures for non-normal polynomials.

This would parallel the self-adjoint case, where weak and strong convergence control spectral distributions and edges, but at present this conjectural principle is only known in special cases.

References

It is tempting to conjecture that if a family of random matrices $XN$ strongly converges to a family of limiting operators $x$, then the empirical distribution of the complex eigenvalues of any noncommutative polynomial $P(XN,(XN)*)$ should converge to $P(x,x*)$.

The strong convergence phenomenon (2507.00346 - Handel, 1 Jul 2025) in Section 6.9 (Complex eigenvalues)