Abstract

We consider the least singular value of M=R∗XT+U∗YV, where R, T, U, V are independent Haar-distributed unitary matrices and X, Y are deterministic diagonal matrices. Under weak conditions on X and Y, we show that the limiting distribution of the least singular value of M, suitably rescaled, is the same as the limiting distribution for the least singular value of a matrix of i.i.d. Gaussian random variables. Our proof is based on the dynamical method used by Che and Landon to study the local spectral statistics of sums of Hermitian matrices.

Highlights

  • We consider the least singular value of M = R∗XT + U ∗Y V, where R, T, U, V are independent Haar-distributed unitary matrices and X, Y are deterministic diagonal matrices

  • In this work we prove universality of the least singular value for the matrix

  • Based on resolvent estimates and a precise analysis of the short-time behavior of Dyson Brownian motion [28, 39, 44, 58, 59], it has succeeded in its original goal of establishing the universality of local spectral statistics for Wigner matrices [29, 41, 45,46,47,48,49,50, 61], and has since been applied to investigate universality for numerous other random matrix models

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Summary

Introduction

The problem of effectively bounding the least singular value of a random matrix with independent entries has received tremendous attention from mathematicians and computer scientists [17, 35, 36, 62, 66,67,68,69,70, 72, 74,75,76,77]. Based on resolvent estimates and a precise analysis of the short-time behavior of Dyson Brownian motion [28, 39, 44, 58, 59], it has succeeded in its original goal of establishing the universality of local spectral statistics for Wigner matrices [29, 41, 45,46,47,48,49,50, 61], and has since been applied to investigate universality for numerous other random matrix models. We comment on an interesting difference between the real and complex cases which does not arise in the Hermitian model

Overview
Main result
Unitary Brownian motion
Canceling mesoscopic drift
Concentration of Green’s functions
Asymptotic equations
Weak law
Eigenvector estimates
Deterministic estimates
Well posedness of dynamics
Interpolating process
Conclusion
Diagonal matrices
Unitary flow
Sufficient conditions for positive density
MR-3684307
MR-2661171
MR-3009072
Full Text
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