  We introduce a generalized method of holonomic quantum computation (HQC)
based on encoding in subsystems. As an application, we propose a scheme for
applying holonomic gates to unencoded qubits by the use of a noisy ancillary
qubit. This scheme does not require initialization in a subspace since all
dynamical effects factor out as a transformation on the ancilla. We use this
approach to show how fault-tolerant HQC can be realized via 2-local
Hamiltonians with perturbative gadgets.
