There are quite a few known techniques for proving that a quantum state is entangled, such as the partial transpose, the realignment test, and symmetric extensions. However, the converse problem (i.e., proving that a state is separable) seems to receive a bit less attention. In this talk, we will review how various twirling operations can be used to prove the separability of certain classes of states, and we will use these twirling arguments to establish a strong connection between measures of entanglement and measures of quantum coherence.

Coauthors: Jianxin Chen, Shane Grogan, Chi-Kwong Li, Sarah Plosker