Recent theoretical work on solid-state proposals for the implementation of
quantum computation and quantum information processing is reviewed. The
differences and similarities between microscopic and macroscopic qubits are
highlighted and exemplified by the spin qubit proposal on one side and the
superconducting qubits on the other. Before explaining the spin and
supercondcuting qubits in detail, some general concepts that are relevant for
both types of solid-state qubits are reviewed. The controlled production of
entanglement in solid-state devices, the transport of carriers of entanglement,
and entanglement detection will be discussed in the final part of this review.Comment: 57 pages, 33 figures, review article, prepared for Handbook of
Theoretical and Computational Nanotechnology. v.2: minor revision; references
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