  The tensor-entanglement renormalization group approach is applied to
Hamiltonians that realize a class of topologically ordered states -- string-net
condensed states. We analyze phase transitions between phases with and without
string-net condensation. These phase transitions change topological order
without changing any symmetries. This demonstrates that the tensor-entanglement
renormalization group approach can be used to study the phase diagram of a
quantum system with topologically ordered phases.
