Design of magnetic coordination complexes for quantum computing

Abstract

A very exciting prospect in coordination chemistry is to manipulate spins within magnetic complexes for the realization of quantum logic operations. An introduction to the requirements for a paramagnetic molecule to act as a 2-qubit quantum gate is provided in this tutorial review. We propose synthetic methods aimed at accessing such type of functional molecules, based on ligand design and inorganic synthesis. Two strategies are presented: (i) the first consists in targeting molecules containing a pair of well-defined and weakly coupled paramagnetic metal aggregates, each acting as a carrier of one potential qubit, (ii) the second is the design of dinuclear complexes of anisotropic metal ions, exhibiting dissimilar environments and feeble magnetic coupling. The first systems obtained from this synthetic program are presented here and their properties are discussed.

An electrostatic model for the determination of magnetic anisotropy in dysprosium complexes

“…Analogous arguments can be made for compound 11 where the b-diketonate oxygen donors are in a similar trapezium-shaped arrangement, however, the coordination environment now contains two chelating nitrate anions. The oxygen atoms in NO 3 À have a larger negative partial charge than those in the b-diketonates, but this is offset by the positive charge on the nitrogen atom, which has an attractive effect on the electron density. Therefore, more-or-less the same anisotropy axis as in compound 10 is observed for compound 11, along the diketonate-diketonate vector (Supplementary Fig.…”

“…Such is the diversity of this field that their application reaches from magnetic resonance imaging and cell labelling 1,2 , to potential building blocks of quantum computers 3 . The pursuit of such applications relies on detailed knowledge of the magnetic anisotropy, which, while being completely defined in cases of high symmetry, is difficult to elucidate in low-symmetry complexes.…”

Determining Key Local Vibrations in the Relaxation of Molecular Spin Qubits and Single-Molecule Magnets

“…This means having a highly isotropic electron spin (i.e., a very small spin-orbit coupling); this would be the case of organic radicals or, among metals, of Gd 3+ spin qubits. [19] Often, magnetic anisotropy is desirable since it facilitates qubit addressing; [20] in this case one needs to engineer vibrational modes whose action hardly affect the relevant molecular orbital energies contributing to gz. This last situation can be encountered, for example, when vibrational modes and molecular orbitals are of different symmetry.…”

Modulating the Slow Relaxation Dynamics of Binuclear Dysprosium(III) Complexes through Coordination Geometry

“…The importance of SMMs is that, even in the absence of an external magnetic field, they can preserve the magnetization for long period of time at low temperatures. After an extensive research on 3d metal complexes in the last decade [2][3][4], a rapid development of Ln based SMMs has been observed in recent years [5][6][7][8][9]. Compared to 3d metals, Ln based SMMs are mostly investigated owing to the fact that the Ln III ions such as Dy III , Tb III , Er III , and Ho III have huge and unquenched orbital angular momentum [10][11][12] which causes substantial magnetic anisotropy.…”