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Optical Quantum Control of Magnetic Molecules

Final Report Summary - OPTOQMOL (Optical Quantum Control of Magnetic Molecules)

A revolution is underway, as molecular nanomagnets are establishing a fundamental link between spintronics, molecular electronics and quantum computation. Coherent control and molecular spintronics is the ultimate goal, promising the control of both spin and charges in electronic devices containing only one or a few molecules. This field, still in its infancy, poses problems of fundamental physical interest and holds promise for future applications. OptoQMol performed an ambitious multidisciplinary study to understand the effect of electronic excitations on the coherence properties of molecular magnetic materials, and use it to manipulate molecular magnetic materials.
Up to now, molecular transport phenomena have been studied by placing a single molecule between two bulk electrodes, either via break junctions or using the conducting tip of a scanning tunneling microscope. For magnetic molecules this approach has some drawbacks. First of all the time resolution of the experiments is limited and we have no access to the details of the processes involved. Secondly we cannot directly measure the magnetization of the molecule, and we cannot know the effect of the electron flow on the magnetic centre and on spin coherence. Eventually, in break junctions, the molecules are randomly positioned, so that the mutual direction of the electron flow and the magnetization is unknown, and the device is not clearly defined. All these drawbacks have severely limited our understanding of the interaction of flowing electrons with molecular spin centres, and in particular the effects on the magnetization dynamics and coherence times of the spins. This last point is of particular importance for the development of coherent spintronic devices, which hold great promise for quantum computation.
OptoQMol, a strongly multidisciplinary project, has contributed to establishing an original methodology that overcomes these difficulties and opens the way to a very precise understanding of the electron-spin interactions. Its results have afforded an ultra-clean system, with a perfectly defined geometry of the magnetic and electronic elements.Owing to instrumentation that combines optical and electron paramagnetic resonance techniques with ns time resolution, we could directly access the effect of electron flow on the magnetic and coherent properties of the molecular spin centres. The unprecedented accuracy and cleanliness obtained are now opening a totally new area of experimental and theoretical investigation.