  Quantum entanglement plays an important role in quantum computation and
communication. It is necessary for many protocols and computations, but causes
unexpected disturbance of computational states. Hence, static analysis of
quantum entanglement in quantum programs is necessary. Several papers studied
the problem. They decided qubits were entangled if multiple qubits unitary
gates are applied to them, and some refined this reasoning using information
about the state of each separated qubit. However, they do not care about the
fact that unitary gate undoes entanglement and that measurement may separate
multiple qubits. In this paper, we extend prior work using stabilizer
formalism. It refines reasoning about separability of quantum variables in
quantum programs.
