Magnetic qubits as hardware for quantum computers

Quantum-cellular-automata quantum computing with endohedral fullerenes

“…Meeting such ideals in practice is very demanding. It is believed by some that a solid-state implementation could prove highly advantageous in terms of the scaling up of the number of spin sites and many solid-state proposals for a quantum information processor are currently under study [3,4,5]. However, to achieve (iv), usually requires the spin-sites to be located within a near-perfect crystal lattice and this leads to great difficulties in satisfying (i) and (ii) above.…”

Quantum entanglement of anisotropic magnetic nanodots

“…The exchange interaction may originate from various physical mechanisms-e.g., from the net Ruderman-KittelKasuya-Yosida (RKKY) interaction with a nonferromagnetic metallic substrate or medium [9,10]-or it may be realized by means of a nanojunction (e.g., a ferromagnetic wire bridging the dots and having a diameter of a few interatomic distances yields an effective exchange coupling that depends on the wire's length and cross sectional area), or as proposed in [1], by coupling neighboring magnetic dots through inductive superconducting loops, where the coupling J depends on the current induced in the loop by one spin and the field produced at the site of the other. A key point is that these means of introducing coupling allow one to control the value of J, which facilitates realization of two-qubit gates, as discussed in [11].…”

“…Recently [1], mesoscopic magnetic particles have been analyzed as potential qubits for quantum computing and their properties have been compared to DiVincenzo's criteria [2] for practical quantum computing devices. These nanometersized particles have large magnetic moments, making them easier to produce and to measure than other spin-based systems.…”

Diffusion inélastique des neutrons sur les aimants moléculaires

“…Avec les agrégats moléculaires, on cherche à créer une quantité élémentaire ("bit") d'information aussi petite que possible. Ces bits quantiques magnétiques [31,65,75,112] sont l'étape ultime de la miniaturisation, cependant, l'environnement cristallin (interactions avec le monde extérieur), modifiant la stabilité et la dynamique de ces sytèmes (phénomènes de décohérence quantique), conduit à une perte de l'information portée par la molécule et constitue un obstacle majeur au développement de la spintronique moléculaire [94]. Un travail récent de "fonctionalisation" de ces matériaux moléculaires a été entrepris notamment sur des surfaces [34,70,100], ou par organisation en films de LangmuirBlodgett [45,46,102].…”