The allure of a quantum computer has drawn many researchers to study a wide variety of two-level quantum systems to represent quantum bits of information. Depending on the state such a “qubit” occupies, it might represent a binary “0” or “1,” or a superposition of those states. Physical realizations of qubits developed so far include the flux in a superconducting system, the polarization of a photon, and the electronic or nuclear spin of an atom or ion. Each realization has its own set of strengths and weaknesses.
One other candidate is the electron spin carried by a molecule, especially a molecule with one or more metal ions. Such molecular nanomagnets, which can have large spins, are embedded in a solid-state system such as a crystal. The attraction of molecular systems arises from the ability of chemists to synthesize a large number of identical entities and to tailor the magnetic properties...
