Finding the singularity of a matrix is a basic problem in linear algebra. Chu and Schnitger [SC95] first considered this problem in the communication complexity model, in which Alice holds the first half of the matrix and Bob holds the other half. They proved that the deterministic communication complexity is Omega(n^2 log p) for an n by n matrix over the finite field F_p. Then, Clarkson and Woodruff [CW09] introduced the singularity problem to the streaming model. They proposed a randomized one pass streaming algorithm that uses O(k^2 log n) space to decide if the rank of a matrix is k, and proved an Omega(k^2) lower bound for randomized one-way protocols in the communication complexity model. We prove that the randomized/quantum communication complexity of the singularity problem over F_p is Omega(n^2 log p), which implies the same space lower bound for randomized streaming algorithms, even for a constant number of passes. The proof uses the framework by Lee and Shraibman [LS09], but we choose Fourier coefficients as the witness for the dual approximate norm of the communication matrix. Moreover, we use Fourier analysis to show the same randomized/quantum lower bound when deciding if the determinant of a non-singular matrix is a or b for non-zero a and b.
This paper investigates the generation of complex quantum states using a dynamic matrix approach. Traditional matrix operations are often static, limiting the potential for efficient computation and communication in the quantum realm. This work proposes a novel algorithm that leverages the inherent adaptability of matrices to generate novel quantum states, specifically tailored for applications in quantum computing and quantum communication. The core mechanism centers around the design of a 'dynamic matrix' generation algorithm, aiming to surpass the limitations of static matrix operations by employing self-adaptive matrix transformations. The paper presents a detailed explanation of the algorithm's design, its operational principles, and preliminary results demonstrating its effectiveness in generating complex quantum states. The research explores how this dynamic matrix approach can enhance the capabilities of quantum algorithms and protocols.
We fully determine the communication complexity of approximating matrix rank, over any finite field F. We study the most general version of this problem, where0⩽r<R⩽nare given integers and Alice and Bob need to determine whether their respective matricesA,B∈Fn×nsatisfy rk(A+B)=rversus rk(A+B)=R. We show that this problem has commu-nication costΩ(r2log∣F∣), which is optimal. Our lower bound holds even for quantum protocols and even for error probability21(1−∣F∣−r/3), which too is optimal because this problem has a two-bit classical protocol with error21(1−∣F∣−Θ(r)). Prior to our work, lower bounds were known only for constant-error protocols and only for consecutive integersrandR, with no implication for the approximation of matrix rank. We also settle an analogous question for subspaces, where Alice has a subspaceS, Bob has a subspaceT) and they need to approximate the dimension of the subspaceS+Tgenerated bySandT(equivalently, approximate the dimension ofS∩T). As an application, we obtain anΩ(n2log∣F∣)/kmemory lower bound for any streaming algorithm withkpasses that approximates the rank of an input matrixM∈Fn×nwithin a factor of2−δ, for anyδ>0. Our result is an exponential improvement inkover previous work.