  We propose a general scheme for dissipatively preparing arbitrary pure
quantum states on a multipartite qubit register in a finite number of basic
control blocks. Our "splitting-subspace" approach relies on control resources
that are available in a number of scalable quantum technologies (complete
unitary control on the target system, an ancillary resettable qubit and
controlled-not gates between the target and the ancilla), and can be seen as a
"quantum-controller" implementation of a sequence of classical feedback loops.
We show how a large degree of flexibility exists in engineering the required
conditional operations, and make explicit contact with a stabilization protocol
used for dissipative quantum state preparation and entanglement generation in
recent experiments with trapped ions.
