New Quantum MDS Codes with Flexible Parameters from Hermitian Self-Orthogonal GRS Codes

Let $q$ be a prime power. Let $\lambda>1$ be a divisor of $q-1$, and let $\tau>1$ and $\rho>1$ be divisors of $q+1$. Under certain conditions we prove that there exists an MDS stabilizer quantum code with length $n=\lambda \tau \sigma$ where $2\le \sigma \le \rho$. This is a flexible construction, which includes new MDS parameters not known before.