Revising the Church-Turing thesis [extended-church-turing]

The extended Church-Turing thesis is the belief that Turing machines capture our intuitive notion of what is efficiently computable. It postulates that everything we can compute in time $t(n)$ on any physical computer can be computed on a Turing machine in time $O\left( {t(n)}^{c} \right)$, for some constant $c$.

Is this true, does it hold? Maybe not, with newer forms of computation like quantum computers.