Entanglement dynamics of many-body quantum states with evolving system conditions

The entanglement analysis of a pure state of a many-body quantum system requires a prior information about its density matrix/ state matrix, obtained in principle by solving the Hamiltonian matrix. The missing information due to complexity of the many-body interactions however renders it necessary to consider an ensemble of Hamiltonians and thereby an ensemble of pure states. This in turn leaves a statistical description of the entanglement measures as the only option. We consider physical Hamiltonians that can be modelled by a multiparametric Gaussian ensembles, theoretically derive the state ensembles for its eigenstates and analyze the effect of varying system conditions on its entanglement statistics. Our approach leads to a single parametric based common mathematical formulation for the evolution of the statistics of different state ensembles. The parameter turns out to be a single functional of the system parameters and thereby reveals a deep web of connection underlying different quantum states.