Computing on Quantum Shared Secrets for General Access Structures

We introduce a method for performing universal quantum computation on quantum states shared according to general access structures. This generalizes recent attempts for doing quantum computation on $(n,n)$ threshold schemes. In a general access structure certain authorized subsets, depending on their weights, can retrieve a secret shared state, and only by their collaboration universal quantum computation can be performed on the shared state. To achieve this we have used concatenation of seven-qubit codes.