Un monocristal de nanoaimants est un objet quantique macroscopique. Le premier objet de cette classe qui ait été découvert est le complexe moléculaire Mn12-ac, de spin par molécule. Avec des écarts tunnels extrêmement petits, ce système a ouvert le domaine de la dynamique quantique lente (incohérente) permettant, entre autre, l'étude d'effets réciproques entre magnétisme classique et quantique. La première partie de cet article donne une vue d'ensemble de ce nouveau type de mésoscopie. Une extension au cas des ions de Terres Rares est présentée dans la seconde partie. Elle montre que le magnétisme mésoscopique peut atteindre l'échelle atomique. Des modifications se produisent dans le bain de spin, qui permettent l'observation d'états intriqués à deux ou quatre corps. Ce domaine est étroitement connecté à celui des mémoires quantiques pour le calcul quantique à l'état solide.
A single crystal made of nanomagnets is a macroscopic quantum object. The first of this class to have been discovered is the so-called molecular complex Mn12-ac with a spin per molecule. With vanishingly small tunneling gaps this system opened the field of slow quantum dynamics (incoherent), with the study of interplays between classical and quantum magnetism in particular. The first part of this article gives an overview of this new type of mesoscopy. An extension to the case of non-interacting rare-earth ions is presented in the second part, showing that mesoscopic magnetism can reach the atomic scale. Modifications occur in the spin-bath, allowing the observation of two- and four-spins entanglements. This field is narrowly connected with the one of solid-state spin qubits for quantum computation.
@article{CRPHYS_2005__6_9_934_0, author = {Bernard Barbara}, title = {Quantum nanomagnet}, journal = {Comptes Rendus. Physique}, pages = {934--944}, publisher = {Elsevier}, volume = {6}, number = {9}, year = {2005}, doi = {10.1016/j.crhy.2005.10.003}, language = {en}, }
Bernard Barbara. Quantum nanomagnet. Comptes Rendus. Physique, Volume 6 (2005) no. 9, pp. 934-944. doi : 10.1016/j.crhy.2005.10.003. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2005.10.003/
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