Variational determination of multi-qubit geometrical entanglement in
  NISQ computers
Current noise levels in physical realizations of qubits and quantum
operations limit the applicability of conventional methods to characterize
entanglement. In this adverse scenario, we follow a quantum variational
approach to estimate the geometric measure of entanglement of multiqubit pure
states. The algorithm requires only single-qubit gates and measurements, so it
is well suited for NISQ devices. This is demonstrated by successfully
implementing the method on IBM Quantum devices for Greenberger-Horne-Zeilinger
states of $3$, $4$, and $5$ qubits. Numerical simulations with random states
show the robustness and accuracy of the method. The scalability of the protocol
is numerically demonstrated via matrix product states techniques up to $25$
qubits.
A. D. Muñoz-Moller L. Pereira L. Zambrano J. Cortés-Vega A. Delgado