Numerical search for universal entanglers in C3xC4 and C4xC4

Abstract

A universal entangler is quantum gate able to transform any disentangled state in an entangled state. Although universal entanglers are abundant in arbitrary high dimensional spaces, to verify if a quantum gate is a universal entangler is a hard task since it is not known which property of the unitary matrix is responsible for such behavior. In this direction, the present work shows the results of an algorithm based on differential evolution that tests universal entanglers in C3xC4 and C4xC4. We present two good candidates for each cited space and we show that a candidate found in the literature is not a universal entangler.