An algorithm to explore entanglement in small systems. (arXiv:1711.07943v1 [quant-ph])
A quantum state's entanglement across a bipartite cut can be quantified with
entanglement entropy or, more generally, Schmidt norms. Using only Schmidt
decompositions, we present a simple iterative algorithm to numerically find
pure states that maximize Schmidt norms, potentially minimizing or maximizing
entanglement across several bipartite cuts at the same time, possibly only
among states in a specified subspace.
Recognizing that convergence but not success is certain, we ask how this
algorithm can help to explore topics ranging from fermionic reduced density
matrices and varieties of pure quantum states to absolutely maximally entangled
states and minimal output entropy of channels.