ABSTRACT
Recently the coherent dynamics of elementary excitations in semiconduc-
tor heterostructures has attracted considerable interest for applications in
quantum information processing such as cryptography or computing [1]. In
the fields of atom quantum optics and nuclei magnetic resonance it is rather
easy to identify well defined two-level systems which can be used as car-
riers of quantum information (quantum bits) and are well separated from
the environment. Therefore the quantum information activities started to
flourish in these fields due to the superior coherence properties of the ele-
mentary excitations. Quite a few proof-of-principle experiments have been
demonstrated, such as few qu-bit entanglement, quantum gate operation
and design of simple quantum processors [1]. However, currently these ap-
proaches appear to be limited due to the lack of scalability towards large
numbers of involved qu-bits, which is less a problem for quantum commu-
nication but which is indispensable for quantum computing.
