Composite anyon coding and the initialization of a topological quantum computer

Understand

Schemes for topological quantum computation are usually based on the assumption that the system is initially prepared in a specific state.

• In practice, this state preparation is expected to be challenging as it involves non-topological operations which heavily depend on the experimental realization and are not naturally robust against noise.
• Here we show that this assumption can be relaxed by using composite anyons: starting from an unknown state with reasonable physical properties, it is possible to efficiently distill suitable initial states for computation purely by braiding.
• This is achieved by encoding logical information in a subsystem code with gauge system corresponding to the internal degrees of freedom of composite objects.