Dynamical Layer Decoupling in a Stripe-Ordered High-$T_c$ Superconductor

In the stripe-ordered state of a strongly correlated two-dimensional electronic system, under a set of special circumstances, the superconducting condensate, like the magnetic order, can occur at a nonzero wave vector corresponding to a spatial period double that of the charge order. In this case, the Josephson coupling between near neighbor planes, especially in a crystal with the special structure of La$_{2-x}$Ba$_x$CuO$_4$, vanishes identically. We propose that this is the underlying cause of the dynamical decoupling of the layers recently observed in transport measurements at $x =1/8$. \newline [1] E. Berg et al, PRL {\bf 99}, 127003 (2007)