Invisible cloaks provide a way to hide an object under the detection of waves. A perfect cloak guides the incident waves through the cloaking shell without any distortion. In most cases, some important quantum degrees of freedom, e.g. electron spin o
r photon polarization, are not taken into account when designing a cloak. Here, we propose to use the temporal steering inequality of these degrees of freedom to detect the existence of an invisible cloak.
