Beating no-go theorems by engineering defects in quantum spin models

  http://arxiv.org/pdf/1406.7239v1.pdf

You might find this paper interesting

From their Conclusion Section :
"There is an ongoing effort in conquering no-go theorems
in quantum mechanics either by going beyond the
static framework of the quantum formalism [29] or by relaxing
quantum dynamical postulates like unitarity [30].
The work presented in this paper shows another path for
overcoming the no-go theorems of ordered systems, while
still remaining within the quantum realm, by introducing
impurities or defects."