Precise transition for complex symmetric Gaussian-product matrices

Characterize the precise location of the transition between Gaussian behavior and non-Gaussian behavior for the complex symmetric random matrices $GG^T/\sqrt{K}$, where $G$ is an $N\times K$ matrix of independent standard complex Gaussian entries.

Background

The paper proves that the total variation distance between the symmetric Gaussian ensemble and the normalized complex product ensemble GGT/KGG^T/\sqrt{K} is O(N/K)O(N/\sqrt{K}), and therefore tends to zero when N=o(K)N=o(\sqrt{K}). The authors compare this range with the known Θ(K1/3)\Theta(K^{1/3}) transition for GOE behavior of real Wishart matrices. They leave unresolved the corresponding sharp transition for the complex symmetric product ensemble considered in the paper.

References

The $N=o(\sqrt{K})$ condition differs from the $\Theta(K{1/3})$ transition for GOE (Gaussian Orthogonal Ensemble) behavior of Wishart matrices with $K$ degrees of freedom . It remains to locate the precise location of the transition in this case.

Proof of the hiding conjecture for Gaussian boson sampling with an arbitrary number of squeezed input modes  (2608.19314 - Shou et al., 19 Aug 2026) in Remark following Theorem 2 (Section 1, Main results)