Fault-tolerant computation without concatenation

It has been known that error-correction via concatenated codes can be done with exponentially small failure rate if the error rate for physical qubits is below a certain accuracy threshold (probably 10^-3 - 10^-6). Other, un-concatenated codes with their own attractive features - e.g., a threshold of 10^-2 - have also been studied. A method to obtain universal computation is presented here which does not rely on any concatenated structure within the code itself, but instead emulates this structure with logical qubits in order to construct an encoded Toffoli gate. This realizes 10^-2 as a threshold for fault-tolerant quantum computation