Simulation and Development of Azafullerene Qubits on Diamond Substrates
Abstract: Azafullerene (C59N) is a spin-active, radical species belonging to the fullerene family. The delocalized spin ½ on the cage is a two-level system that can be manipulated as a qubit. The stability of C59N is enhanced by using a protective molecule, [10]CPP; through supramolecular noncovalent interactions, these two molecules form the C59N⊂[10]CPP complex. This structure possesses the same spin characteristics as azafullerene, while remaining stable at room temperature for years. This is why C59N⊂[10]CPP shows promise in the fields of molecular electronics, quantum information processing (QIP), and nanomagnets. In particular, we are studying the implementation of a molecular spin measurement system using fluorescence from colored defects in diamond.
In this thesis, first-principles calculations using density functional theory (DFT) reveal the electronic stability (charge and spin) of C59N and the NV center in diamond. NV-center fluorescence microscopy provides information on the characteristics of C59N and reveals charge instability dependent on the surface chemistry of diamond. We study surfaces such as Au(111), Ag(111), FeO(001), and graphene, onto which [10]CPP and then C59N are deposited to create a monolayer of C59N⊂[10]CPP. The deposits are characterized by STM, XPS, and NEXAFS, revealing complex and variable structures in which the structure of C59N⊂[10]CPP depends on the deposition and annealing conditions. The supramolecular complex retains its spin activity depending on the surface used.
Keywords: ab initio, density functional theory, supramolecular complex, color defect, NV center, magnetic resonance
Simulation and Development of Azafullerene Qubits on Diamond Substrates
Abstract: Azafullerene (C59N) is a spin-active molecule—a radical species—from the fullerene family. The delocalized spin of ½ on the cage constitutes a two-level system that can be manipulated as a qubit. The stability of C59N is enhanced by using a protective molecule, [10]CPP; through non-covalent supramolecular interactions, these two molecules form the C59N⊂[10]CPP complex. This structure retains the same spin characteristics as azafullerene, while remaining stable at room temperature for years. This is why C59N⊂[10]CPP shows promise in the fields of molecular electronics, quantum information processes (QIP), and nanomagnets. In particular, we are studying the implementation of a molecular spin measurement system using fluorescence from color centers in diamond.
In this thesis, first-principles calculations using density functional theory (DFT) reveal the electronic stability (charge and spin) of C59N and the NV center in diamond. Fluorescence microscopy of the NV center provides information on the characteristics of C59N and reveals charge instability depending on the surface chemistry of diamond. We study surfaces such as Au(111), Ag(111), FeO(001), and graphene, onto which [10]CPP and then C59N are deposited to form a monolayer of C59N⊂[10]CPP. The deposits are characterized by STM, XPS, and NEXAFS; they reveal complex and variable phases in which the structure of C59N⊂[10]CPP depends on the deposition and annealing conditions. The supramolecular complex retains its spin activity depending on the surface used.
Keywords: ab initio, density functional theory, supramolecular complex, color center, NV center, magnetic resonance
