Products of independent Gaussian random matrices

Ipsen JR. Products of independent Gaussian random matrices. Bielefeld: Bielefeld University; 2015

Multiplicative convolution of real asymmetric and real anti-symmetric matrices

Kieburg M, Forrester PJ, Ipsen JR. Multiplicative convolution of real asymmetric and real anti-symmetric matrices. Advances in Pure and Applied Mathematics. 2019;10(4):467-492.The singular values of products of standard complex Gaussian random matrices, or sub-blocks of Haar distributed unitary matrices, have the property that their probability distribution has an explicit, structured form referred to as a polynomial ensemble. It is furthermore the case that the corresponding bi-orthogonal system can be determined in terms of Meijer G-functions, and the correlation kernel given as an explicit double contour integral. It has recently been shown that the Hermitised product X-M ... X(2)X(1)AX(1)(T)X(2)(T) ... X-M(T), where each X-i is a standard real Gaussian matrix and A is real anti-symmetric, exhibits analogous properties. Here we use the theory of spherical functions and transforms to present a theory which, for even dimensions, includes these properties of the latter product as a special case. As an example we show that the theory also allows for a treatment of this class of Hermitised product when the X-i are chosen as sub-blocks of Haar distributed real orthogonal matrices

Weak commutation relations and eigenvalue statistics for products of rectangular random matrices

Ipsen J, Kieburg M. Weak commutation relations and eigenvalue statistics for products of rectangular random matrices. Physical Review E. 2014;89(3): 32106.We study the joint probability density of the eigenvalues of a product of rectangular real, complex, or quaternion random matrices in a unified way. The random matrices are distributed according to arbitrary probability densities, whose only restriction is the invariance under left and right multiplication by orthogonal, unitary, or unitary symplectic matrices, respectively. We show that a product of rectangular matrices is statistically equivalent to a product of square matrices. Hereby we prove a weak commutation relation of the random matrices at finite matrix sizes, which previously has been discussed for infinite matrix size. Moreover, we derive the joint probability densities of the eigenvalues. To illustrate our results, we apply them to a product of random matrices drawn from Ginibre ensembles and Jacobi ensembles as well as a mixed version thereof. For these weights, we show that the product of complex random matrices yields a determinantal point process, while the real and quaternion matrix ensembles correspond to Pfaffian point processes. Our results are visualized by numerical simulations. Furthermore, we present an application to a transport on a closed, disordered chain coupled to a particle bath

Products of Rectangular Random Matrices: Singular Values and Progressive Scattering

Akemann G, Ipsen J, Kieburg M. Products of Rectangular Random Matrices: Singular Values and Progressive Scattering. Physical Review E. 2013;88(5): 52118.We discuss the product of $M$ rectangular random matrices with independentGaussian entries, which have several applications including wirelesstelecommunication and econophysics. For complex matrices an explicit expressionfor the joint probability density function is obtained using theHarish-Chandra--Itzykson--Zuber integration formula. Explicit expressions forall correlation functions and moments for finite matrix sizes are obtainedusing a two-matrix model and the method of bi-orthogonal polynomials. Thisgeneralises the classical result for the so-called Wishart--Laguerre Gaussianunitary ensemble (or chiral unitary ensemble) at M=1, and previous results forthe product of square matrices. The correlation functions are given by adeterminantal point process, where the kernel can be expressed in terms ofMeijer $G$-functions. We compare the results with numerical simulations andknown results for the macroscopic density in the limit of large matrices. Thelocation of the endpoints of support for the latter are analysed in detail forgeneral $M$. Finally, we consider the so-called ergodic mutual information,which gives an upper bound for the spectral efficiency of a MIMO communicationchannel with multi-fold scattering